Adonael's
Resin Printing
FAQ
Before Printing
Introduction, Why I Wrote This
I am a professional printer who has become somewhat of an expert in consumer-level resin printing. I arrived at the conclusions in this FAQ through research, experimentation, experience, and deduction. I've printed everything from 32mm minis to huge 800mm statues in half a dozen large hollow pieces, sent them all around the world, and handled every aspect of the process from digital sculpting to painting. Unlike what seems to be most who feel like they should give out advice, I grew up watching Mythbusters and if there's one thing I've taken away from that and applied to what I do in life it is this: Don't assume, try it and test it. I have already disproven or confirmed multiple assumptions/myths in the resin printing community this way. Simply by being that one person willing to take action and DO.
That brings me to why I wrote this FAQ, all the basic and simple questions I see asked on the internet everyday from beginners to semi-experienced regular at home hobbyists alike are honestly annoying. There really isn't much in the way of a single comprehensive easily navigated resource anywhere that one can turn to for simple answers on the majority of processes, information and problems related to consumer resin printing. Most people don't want to know the science behind it, or to read a dozen technical articles from different sources, they just want to know what works. Make no mistake, all the answers are out there, I have never once made a post with a question of my own or seeking help, I was always able to find the answer within minutes simply by searching for it. The reason I wrote this is so that I could stop wasting my time answering those same questions over and over from others, as my own nature compels me to help and inform, and instead throw a link at it. Also, and this is important, to combat the misinformation and stupid or wrong advice that many others continue to give as answers to those same questions.
That all being said there are of course gaps in my experience and knowledge, I can't do everything after all and I'm not a youtuber with access to a dozen different machines, this is all general information not specific to any model or brand of printer/resin, and I won't comment on or make uneducated guesses on what I don't know, you'll have to find more information elsewhere if it isn't covered here. Additionally much of what I do isn't exactly 'by the book' so to speak, and everybody's printer and comfort level is different. Use my advice in combination with other sources of information (by which I mean not some random drooling moron on reddit who sits their printer in their kitchen without a care in the world or thinks opening a window solves all the world's problems), it's not a definitive work. Except safety, never compromise on safety, if an anti-vaxxer or anti-masker tells you that you shouldn't protect yourself, your child, or your loved ones from harm, would you listen to their mentally ill ass? I should hope not, because otherwise you have no business owning or using a resin printer and should find a different hobby more your speed, like children's colouring books. Safety is easy, simple, and inexpensive.
Resin Printing Safety? (Gloves, Mask, Location/Ventilation)
It's important to always keep in mind that resin is a dangerous and toxic chemical, it must at all times be treated with a healthy amount of caution. Different people are more or less sensitive to resin (and repeated exposure increases sensitivity), some are outright allergic to it, including myself. If it contacts my skin I will get an extremely itchy rash in a large area, not just where it contacted. Symptoms of exposure to resin via touch or breathing can be headaches, dizziness, shortness of breath, rashes, itchiness, and worse. I've seen at least one person who suffered the effects of a bad chemical burn after skin contact with resin, and another who passed out from the fumes of both the machine and their IPA wash.
Here's the good news though, even though I'm allergic to it and work with it almost every day I never have any issues because I simply follow the basic necessary resin handling safety. Properly filtered half-face mask, nitrile gloves, apron, isolation plus ventilation of the machine/wash. Basically, don't let it touch your skin, and don't ever breathe in the fumes or airborne particles. That's it, it's that simple! Ignoring such a simple thing as safety is pure dumbassery, I've seen photos people have posted with liquid resin literally dripping over their bare hands as they hold a print they just pulled off the printer, or wearing a freaking cloth dust mask or medical mask, or complaining about the smell of the harmful fumes they're breathing in because they don't wear anything, don't be that person, you'll suffer the consequences sooner or later (hopefully sooner for those who choose to ignore safety and encourage others to as well). Follow the basic necessary safety at all times, make it a habit and you will never have to worry, it is easy simple and inexpensive, there are no excuses.
Let's go into detail:
Gloves. Disposable nitrile gloves are the accepted standard, and extra thick ones preferred. Regular latex is no good. I also have a pair of elbow length dipped chemical handling gloves, I wear these over my nitrile gloves up until the support removal step, basically during the grunt work where I don't need precision and they will be guaranteed to be touching liquid resin and reaching deep into the IPA wash. For this reason (and because I get the thick ones) I usually use each pair of nitrile gloves for two prints rather than just one, it's easy to burn through boxes of these things if you're printing a lot. Bottom line, never handle liquid resin without gloves on, and never handle a print without gloves on until it has been cured.
Mask. You require a proper filtered half-face mask. The most common one being the 3M 7502 style half-face respirator with 6001CN organic vapour filter cartridges and N95 cotton filters over top. A dust mask? Won't do shit. A medical mask? Won't do shit. An air purifier or open window? Won't do shit. The fumes from resin (and your wash) are toxic, if you can smell it you're breathing it in, and that's only if you have a sense of smell, judging by the comments I've seen many people printing don't, so even that isn't a reliable indication. There are also suggestions that those charcoal filters in some printer models just remove the smell, not the aspects of the fumes which matter, so you can't trust that either, and it won't matter once you open the thing and expose yourself to the liquid resin anyway. Bottom line, any time any container or vessel or printer with resin or wash is open you have this mask on, any time you are in a space with an active resin printer which isn't completely isolated and vented outside you have this mask on. When do you replace the filters? When they become saturated and you begin to smell the fumes while wearing the mask, for me this takes about 3 months. I use grey resin, by the time they're replaced the cotton filters on the outside have literally been discoloured grey by resin particles, you can see the contrast against the clean edges where they were held by the cover, without a mask that is what you are breathing into your lungs, liquid plastic. There are people who will suggest that touching/ingesting is the real danger of toxicity with resin and not worry about fumes so much, do they not know what smell is? I'd say those particles of liquid resin entering your lungs counts as both touching and ingesting when it's inside you.
Printer/wash location, isolation and ventilation. Ok, so you have your mask, but where are those fumes from the resin, printer and wash going? Complete isolation is the best and easiest solution if it's possible, a space separate to any living spaces or their air circulation which is almost never visited except for the purpose of using the printer with a mask on. For me currently this is a garden shed, separate and complete isolation. However something like that isn't always available, or even an option at all such as in an apartment or unit. Which brings us to ventilation, the goal is still to isolate the machine and wash as much as possible, in a disused room for example, and then implement ventilation. As above, putting an air purifier next to it or opening a window and pointing a fan at it isn't going to do shit. The fumes and the smell will absolutely spread from whatever room they are in and contaminate other areas of the house etc and affect you and others when you don't have the mask on. Typically ventilation involves trapping the fumes, and removing them to the outside via a tube connected to a window. This can be done any number of ways, it can be attached to the printer itself through a hole added to the print chamber, or more commonly the entire printer can be placed inside a larger enclosure which then has a tube attached to it, such as a cupboard, a grow tent (inexpensive and set up exactly for this, very convenient), a custom build enclosure, or other. A fan can be used to push air into the enclosure, installed at the beginning or end of the tube to pull fumes out, or both. You have to remember that when the printer/wash/enclosure is open, as it will be necessary to do, it will still spread through the space they're placed in, so you need to be able to easily ventilate that too. Bottom line here, a resin printer should not be used in an living space, your bedroom, living room, home office, hobby room, kitchen, bathroom, all are bad ideas unless you set up the proper enclosure and ventilation.
Apron. Not exactly necessary, in fact I rarely ever see it mentioned, but I never print, post-process or paint without my trusty waxed canvas apron on, it'll protect you and your clothes from any drips or splashes. This is also a good place to mention something else which rarely is, footwear. Very easy for a drop of resin to fall off the build plate or resin bottle onto your foot, or your resin contaminated wash to drip off your print or gloves, it's a good idea to be wearing closed footwear.
List of Tools and Equipment?
This isn't definitive, some of it is optional, and you may find you need other things along the way for your own situation but here's a good starting point:
Proper Filtered Half-Face Mask (3M 7502 style)
Spare Mask Cartridges & Filters
Box of Nitrile Gloves
Apron
Resin Printer
Spare FEP Sheet
Spare Screen (if you use it a lot, don't want to wait 2 weeks for a new one to arrive)
Resin
IPA (or alternative if necessary)
2-3 Wash Containers (or ultrasonic cleaner/wash&cure plus containers)
Paper or Shop Towels
Quality Microfibre Towel (for FEP)
Plastic Tray/s (cafeteria style, for moving around or keeping prints on between steps, I don't have any yet but I should because it would be very useful)
Pair of Elbow Length Chemical Handling Gloves
Safety Glasses
Plastic Scraper
Flat Silicone Spatula
Soft Toothbrush (I use a cheap bamboo toothbrush from a pack off ebay)
LED Re-chargeable Headlamp (I use this because my printer/wash is in a dark space)
Curing Box/Station
Sturdy Level Place To Put Printer (with isolation/ventilation in mind and planned for)
Place To Put Wash
Well-lit Workspace For Post-Processing (not sunlight obviously)
Non-stick Water Proof Mat For Workspace, Silicone or Other
Paper Paint Filters (or re-usable metal/silicone if you can find it)
Spray Bottle For IPA (used for cleaning build plate and tools)
25-50ml No Tip Feeder Syringes (I use this occasionally during cleaning for pushing IPA/Water through a small hollow cavity)
Small Bowl (for water when sanding)
Multiple Beakers (for temporarily holding filtered resin, or mixing resins etc)
Flush Cutters
Scalpel
Tweezers
Needle Nosed Pliers
Super Glue
Roll of Sandpaper or Emery Paper (I use 600 grit, plus scissors for cutting it up)
Random Orbital Sander (optional, could also use something like a palm sander or belt sander)
5ml Flat Tipped Syringe For Liquid Resin
Small UV Torch
Small Sealed Dark Bottle For Liquid Resin For Refilling Syringe (I use a glass vitamin pill bottle that was laying around and keep it in a drawer with the syringe out of any light)
Tray (for evaporating IPA from filtered out resin when recycling wash before curing the resin particles, silicone is best)
Small Biodegradable Plastic Bags (sometimes called kitchen sized, think the vegetable bags at the grocery store, I use these to put all my supports into)
Cordless Drill With Various Sized Drill Bits (sometimes I need to drill holes into prints, optional)
Desk Fan (helps dry things)
Dustpan and Brush (for cleaning up your mat after support removal/clean-up, dump bits into supports bag)
Metal Cubes (I have a handful of 20mm heavy solid brass cubes, they are incredibly useful for leaning prints against when curing or on for strange angles when repairing etc)
Accessible Headphones or Speakers (you're going to be spending a lot of time sitting at your workspace)
Primer (the minimum to completely finish a print, you can use spray can primer, or get a bottle such as Vallejo, and some thinner, brush it on with a paintbrush or spray it on with an airbrush)
Varnish Clear Coat (as mentioned when making a transparent print clear, I use Vallejo Gloss Varnish, slightly thin it and brush it on)
Supporting Prints?
I'll only be explaining the basics here because I am by no means an expert at supporting, I couldn't do it as a service for others and I don't do anything fancy. I am completely okay with extra clean-up work during post-processing, what matters to me is simply the print not failing, I would rather an extra 5 minutes of work than a day to reprint. For videos on advanced techniques and settings etc 3DPrintingPro on Youtube is generally recommended to check out.
So, as I've said elsewhere, always use a raft unless printing directly onto the build plate. A raft creates one unified area where all the supports for a model reach the build plate. One single large surface to adhere to the build plate. It is amazing and it solves or helps avoid so many issues one might otherwise have. It helps build plate adhesion as a larger surface has a stronger bond, and it means each support shares that same strong bond rather than relying on its own small area. It makes prints easier to remove as you simply have to pop off the raft and all the supports remain intact where they are, the entire print from raft to model is one piece you can pick up by the raft or stand on the raft without disturbing anything else. Having to remove a print with individual supports can easily damage the print by tearing off supports as some are moved and others aren't, or during cleaning, and you have to hold it by the model itself which can cause even more damage. I personally use a very thin raft just 5 layers thick in a 'skate' type, which gives all the benefits while using very little resin.
I've covered orientation/angle elsewhere, do this before adding supports. Next, there are generally three types of supports, light/medium/heavy. Personally I stick to mediums for just about everything from miniatures sizes up to large 350mm sizes, they just perfectly balance performance and clean-up, heavies create a lot of damage to detail and potential damage when they are removed, and for me at least light supports never work, they're too weak for anything other than delicate things like teeth, and even then only if they are supported themselves by mediums. For models with attached bases the most important thing is the base, this is when I will use heavy supports on the bottom of the base, the more the better as it will keep it flatter.
So, generally what you will do is add auto-supports, and then go in and add or edit supports manually. The biggest focus being on islands, an island is where part of the print starts printing without being connected to anything else, and a single island can ruin an entire print. You can't print in mid-air, each layer of the print needs to be pulled up off the FEP between layers, and held in place, that can't happen without supports. So if you have an island without a support to hold it then that area of the layer will stay on the FEP, it will cure more with each layer until it reaches the point where it was meant to join with the rest of the model. So either you end up with a flat area where that part was meant to be which is pulled off the FEP by the rest of the model, or the rest of the model can't pull it off and instead it grows which each layer, creating a growing triangle cut out from the model as the patch on the FEP takes more of each layer with it. This can also happen when a support fails. You can see where islands are either by using the slider in the slicer, or for me the black line on the model which highlights the layer the cursor is on, moving it up you will see any area where the highlight starts/appears outside of and unconnected to the line, this is an island. There can also be micro-islands, these are covered in another article.
Islands are certainly not the only consideration when supporting. Supports also need to hold the model in place accurately so it doesn't move between layers, and hold not only the entire weight of what they are supporting but also that weight against the suction forces when it is pulled off the FEP. Think about a humanoid model with an arm casually hanging at its side, you support the islands on the fingers, there are no more islands on the arm, all done right? No. You're asking not just those supports, but the fingers too, to hold that entire arm and keep it in place until it joins the rest of the body at the shoulder. It's simply not going to work. You need additional supports half way up the fingers, on the hand, and along the length of the forearm and upper arm until it reaches the shoulder. Because any sideways length will cause shearing pressure on the supports, like trying to lift a bucket which is on the other end of a broom stick, incredibly difficult compared to just lifting it directly from the handle. Vertical lengths such as a leg may not seem necessary to support, however it's less about holding against suction or weight, and more about holding them in place, to use another analogy, if you only have the foot supports then by the time it reaches the next supported area such as the buttocks it's kind of like trying to balance a fork by holding it at the very tip of the handle, versus holding the middle if there are just a few supports placed up the length to help keep it steady. It may be overkill sometimes, but like I mentioned at the start, I'm fully aware that I do over-support a little and I don't mind.
This brings us back to islands, supports on islands can fail, and the biggest reason for that is because an island is under-supported. Again, you need to think ahead. Say you have a four legged creature, and the belly underneath starts as an island, you slap a support on that island and call it a day, but what are you asking the support to hold? All of every single layer and the expanding surface area until it reaches the next supports or supported part of the model higher up. For major islands like this I will closely surround this first support with 4 more supports one on each side, so in reality this expanding area is supported by a group of 5 core supports, which is much much stronger, and then place supports in another further distanced ring outside that. Always be thinking about how much you are asking your supports to hold and how you can share that load. The further away you get from the initial island, the fewer supports you need as strength is drawn from the collective supports already placed.
Something else to avoid is supports which both begin and end on the model, it's not the end of the world and I certainly have my fair share of them, but it does mean that the support is leaving a mark/damage on two points of the model rather than just one, and the bottom point will be on a highly visible area on the top side of the model. Also supports which travel too far on their own, I'm talking about a single support which needs to support a point right at the top of a large 200mm print for example, all kinds of things can go wrong asking this single thin rod to stay perfectly straight all that distance, consider adding another support or two to this support half way up etc just to help it out.
I won't really get into settings, I don't even remember how I ended up on the settings I use, but another issue that people face is not having a high enough contact depth. Supports need to contact the model to hold it, it's just a fact and can't be avoided. If the contact depth is too low it just won't hold, the grip will be too weak.
Islands, Gotta Catch Em All?
Yes, but also technically no. This can depend a lot on the size of a model, and whether it was resized, particularly scaled down. To be clear though, if a major island is not supported, it will cause a partial failure on your print guaranteed, and it must be said that auto-supports are a starting point, you always need to go in and do some supporting yourself. This question really comes because as many find out, even after painstakingly manually supporting every island you can find, the software will still say there are islands, well chances are these are tiny insignificant islands a single pixel or two in size, they won't affect the print and you don't need to go hunt every single one down, all you'll be doing is causing more damage to your print from supports particularly to fine detail, and wasting time, supporting already takes long enough as it is. If I run a typical print of my own through Photon File Validator for example it'll tell me I have literally hundreds of islands, even though it prints just fine.
Which brings us to scaled down models. Let's say I scale down a large life sized weapon with some texture and grit to it, scratches etc, to 10% size for a figure. When I go to support this thing what will I see? A whole a ton of islands from all those little details. But here's the thing, it's easy to lose perspective when you're in the slicer looking at things zoomed right in, it'll be relatively tiny when it's actually printed and all of those little details and their 'islands' are actually smaller than a pixel and won't be printed at all. You just need to worry about the major islands. Another example, I often print highly detailed/textured statue sized models, where just a forearm can contain hundreds of islands as a result of the texture of the skin, if I tried to slap a support onto every single one of these I'd end up with a solid bar of resin attached to the arm! Simply distributing supports through this area roughly in the worst places, and of course on any major island which is a few layers deep or more, will take care of it, the presence of those other supports and how they affect the immediate area around them during printing evens it all out.
There's no shortcut to experience, and it takes experience to know what's important at what sizes and what you can get away with, but the point is don't get bogged down in worrying over every little thing you see zoomed up close. I once heard of someone in this exact dilemma with a scaled down model who couldn't get out of their comfort zone of perfectly smooth patreon minis, after a month of worrying and not printing the model for their client they decided they'd need to pay to have the file edited and simplified before they could support or print it (at a 45° angle of course, sigh), all they had to do was print the damn thing and in less than one day they would have known everything they needed to from the result. Don't be that person, by the book rules are primarily to help beginners not immediately screw up and not much else, if you want to know something try it, do it, get things done, don't spend a month worrying about less than a dollar worth of resin and a single pixel of cured resin somehow denting your FEP because it wasn't supported.
Hollow Prints?
Hollowing resin prints is very common, and both Chitubox and Lychee have this feature built in. What this does is create a wall or 'shell' on the interior of the object at the thickness you choose. Why print hollow? First and most obviously, it saves a huge amount of resin which would otherwise be used on the interior, depending on size a solid print can use many multiple times more resin than hollow, and resin isn't cheap. Second, solid prints are heavier and also create far more suction while printing, putting far more stress on the supports and build plate adhesion and thus increasing chances of failure, in my experience consumer level printers generally do not like to print solid for medium/large objects.
When to print hollow? Whenever it makes sense, a large amount of people using resin printers do so to print miniatures, and the majority of miniatures are printed solid, they're so small they couldn't be hollowed if you tried or wouldn't be worth the effort regardless. If there's more hollow space than the exterior shell then that's pretty much when it makes sense. Most prints nearing 100mm or more will be this way by default, unless it's a particularly skinny model or the size is made up by wings etc.
How to print hollow? To hollow an object, simply choose your wall thickness and hit the hollow button in Chitubox or Lychee for the selected model. The standard wall thickness is right around 1.5-2mm, this is both an economical and strong thickness, although it is possible to get away with thinner than that, or thicker, although I honestly don't notice much of a strength difference, for particularly large prints like say 300mm I might go up to 2.5mm. Then the most important part, you need to add what are called drain holes (although they fulfil many functions) to any hollow cavity. Two drain holes. Always. One is useless and will create a vacuum. The purpose of these is to relieve pressure while printing, allow liquid resin to leave the cavity while printing, and allow the interior to be cleaned after printing, if you don't then liquid resin will be trapped inside the print and inevitably cause cracks and leaking later, ruining the print. When you hollow the model you need to go down through all the layers using the slider to look at the walls, the main body may not connect to other parts which were hollowed, such as a forearm having a small hollowed cavity but not being connected to the main cavity because the elbow is too thin between them. These small cavities will need their own pair of drain holes in order to be cleaned inside. For the main cavity place the drain holes as low as you can on the model while avoiding noticeable areas, on the bottoms of feet (either through a base, or without one) is a great place to place them, if you can't put them in a relatively hidden area then try to avoid detail or the front of the model, the calf or back of the thigh is usually a decent option. I typically use a 5mm hole for the main drain holes, 7mm for larger models, sometimes even up to 10mm. This is assuming the object isn't being printed directly onto the build plate. For small cavities I will typically use a 3mm hole size, or even 2mm for delicate areas, it doesn't matter where they are as much, try to have them both on opposite sides to eachother, such as on both sides of a forearm. Always hollow a print before supporting it, and it's good practice to orient the model before adding the drain holes.
Using infill? Never. Infill will trap liquid resin and IPA in your print, it can't be cleaned, which will cause leaks and cracks in the print over time, and infill also cannot be cured so it doesn't really add any strength anyway.
There is a separate article for cleaning hollow prints. As a note, supporting a hollow print is typically no different to supporting a solid one if you're doing the usual auto-supports first then manual supports second method, however if you're 100% manually supporting then you will need to support the interior islands. I've never had a print failure due to interior supports/islands when just leaving it to the auto-support function.
Curing Equipment and Methods?
Does a print need to be cured? Yes. You wouldn't believe it but I have actually seen this question multiple times, it's ridiculous, even the most basic guide or research or vague explanation of printing will point out this fact.
Moving on, curing isn't a difficult thing and doesn't have to be expensive either, all you really need is a source of UV light. Which yes, includes the sun which is free, however using the sun to cure your prints is the least recommended way to do it, it's inconsistent, it's dependant on weather, it takes much longer than any other method, and it can only be done during the brightest hours of the day. It's possible, slap your print on a solar powered turntable, or make sure to rotate and flip it regularly to cure all the sides and underneath, and just wait, it'll work eventually.
Second, are Wash & Cure machines, I've covered elsewhere their cleaning functions but what about curing? Well, generally they include a powered turntable to rotate the print, and a strip of high grade UV LED diodes at the back of the machine to cure the print. In short they're perfectly serviceable, and simple, you buy it you use it. The only real drawback being the restrictive dimensions of the machine itself, how will you cure a print in this which can't stand up on its own and when not standing is wider than the turntable and thus can't fit in the machine? It's a real consideration to take into account. There are workarounds, place the object in an empty or water filled clear container, such as the one included for the wash, but it's a bit of a janky solution. The UV light also usually strictly comes from only one side and direction.
Third is where all the options are, complete freedom in design, size and price, the DIY curing box or station. Let's cover the major aspects:
UV light source. The most important component, and remember that the wavelength should be around 405nm, it's entirely possible for you to buy a UV light and have it be ineffective because of the wavelength. For tiny things like miniatures people have found success simply using a nail polish light. Most of the time for a budget option a cheap UV LED strip which plugs into a usb port (a cheap wall plug with usb ports on it is very handy) will be suggested, I didn't have great success with this, it only worked well for a month or two before the strip started fading and becoming useless. However it does have the benefit of being able to completely surround a print and cure it directly from every side at once. There are also small rectangular UV LED lamps being targeted toward resin printing, these can be suitable and generally offer more power than a regular strip does. For me, I needed something larger as I typically print in the 150mm+ range, so what I did was buy a UV LED light from a DJ supply store intended to be used in a club setting. Specifically a 200mm round LED Par Can light, which can function on its own without a controller, and meets the wavelength requirement. Equipment like this is designed to be used for thousands of hours. I went with a relatively budget option, but the sky is the limit including large powerful LED array panels similar to what is found inside resin printers themselves.
The box. Technically, you don't need a box at all, just sit your print on a shelf or desk (on a turntable or not) and point your light source at it, that will work. However unless it's an isolated area you probably don't want to just throw UV light around everywhere, and the print will only be cured from one direction. That's where a box or any sort of enclosure comes in, you can use anything from a spare cardboard box, to a bucket, to a kitchen cupboard to a custom built wooden enclosure. Just make sure it's big enough to fit your largest possible print in, vertically or horizontally. The benefit being you can trap all the UV light, and make it work in your favour by lining the interior surface of your enclosure with a reflective surface to bounce the light around. You can use something as simple as kitchen foil, or reflective tape, or even actual mirror etc. You may also be able to find things like galvanised steel bins/buckets which have a shiny metal interior surface already. You need an opening, a door, a lid, a hatch etc, to insert and remove your prints. You also need to think about where and how you will have the light source, or even multiple light sources. I've often seen an LED lamp attached to the lid from above, I don't like this as the light only coming from above is the least effective direction to cure a print from and you would have to flip it upside down somehow to really get to the bottom which is a difficult proposition for most models. From the side is best, and from all sides is even better, if I ever have the cash I'm getting 4 of my lights together pointing from every side and going nuclear on my prints which will drastically cut down cure time.
Platform. Talking about direction, that brings us to rotation. As mentioned earlier, if the print isn't being rotated (and you're not surrounding it with direct light) you'll have to do it yourself, regularly turning it to cure every side as well as the top/bottom. A common solution is to get a cheap solar powered turntable which can be powered by the UV lights themselves. Although I didn't great results with this either, for many prints it simply wasn't powerful enough to rotate, and the rotation wasn't consistent anyway, plus it was small. I replaced it with a larger usb powered turntable with a mirrored surface. It's good to have a mirrored surface under the print as well, so some light can reach the underside even when it's upright.
Put all this together and you're curing your prints, avoid looking directly at UV light or a direct reflection of it. For details on curing times etc see my other articles. Also one fun idea I've seen someone do, repurposing an old microwave as a curing box, it's self-contained with a door and has a rotating platform already, just remove the microwaving parts, line the inside with reflective material, add a UV light source and off you go. You can even wire it if you have the skills so that setting the timer and hitting start doesn't just rotate the platform but also powers and turns on the light, making it all automated with a built-in timer.
IPA and Other Cleaning Chemical Alternatives?
Let's get this out of the way, 100% IPA (Isopropyl Alcohol) is the best cleaning solution for resin printing, period. It is the goal, the ideal, and it is what I use exclusively with fast and comprehensive results from small to huge prints. However despite being cheap and common here in Australia, it is not an easy thing to come by in many parts of the world, so many people require alternatives. So the higher the % of IPA the better however lower will also work just fine (although not quite as well), in america for example it seems like 91% is the highest available, and in many places as low as 70% is the most common, something like rubbing alcohol is even lower, you may find in your own experience that an alternative works better than a % that low.
Speaking of which, what are some alternatives? Denatured Alcohol (otherwise known as Methylated Spirits) is the main one and generally easy to find in any hardware store. Acetone is a sometimes mentioned one, however it is very harsh, even more human and environment unfriendly than IPA with worse fumes and unfriendly to most plastics used in containers so I wouldn't recommend it. Bio Ethanol is another, I'm not sure how well it works, but it seems easy to get as it is commonly used for many purposes, mostly as fireplace or burner fuel. Then we have degreasing cleaners, these products have different names and brands in different regions so you'll have to look that up yourself but in america the big ones go by Mean Green or Simple Green. Some people have had good results, others not so much, it needs more physical agitation than IPA to clean well so using an ultrasonic cleaner is a good option. It's worth noting here that with a correct cleaning method you will always wash a print in water as a last step for both cleans, but this is particularly true for something like Mean Green which will leave an obvious residue on the print. And now the most expensive alternative, Resinaway developed by Monocure3D, a liquid specifically developed just for cleaning resin prints as well as being non-flammable, not having strong fumes, and lasting longer before needing to be recycled with little evaporation. I do actually have a couple of sample bottles of this stuff, but I've never personally tried it as my typical prints are too large to use with the amount I have.
Water with water washable resin? Self-explanatory, in theory you should just need a container of tap water to clean your prints (never allow resin to go down the drain, water washable does not mean wash you print in the sink under the tap). However from what I've seen it requires a lot of agitation and even brushing in order to clean well, and IPA still cleans it the best (at which point there'd be no point to using water washable as it is reportedly more brittle than regular resin). Does the convenience of not needing to use/store harsh chemicals to clean your prints outweigh the negatives of more difficult cleaning and more brittle prints? That's up to you, but consider that any resin itself is already a toxic chemical, so considering you're already following proper safety for that including wearing a proper filtered mask and gloves how much difference does it really make to your printing process to extend that safety to the wash?
IPA/Alt Containers and Wash Machines?
The most common way to use IPA etc to clean a print is to simply have it in a suitably sized plastic container. Some plastics can be affected by IPA or other chemicals over time and eventually split open causing a huge mess, I've seen this happen to at least one person, but I have no idea how to know what plastic or type of container this could happen to so I have no advice on that. For myself, I just use a generic clear plastic storage container from an office supply store because my wash is large (about 7 litres of IPA, which may be increased in the future as sometimes it is still too small). For regular sized and smaller printers there are definitely options made from glass or Pyrex meant for kitchen/food related storage which are guaranteed to not have any issues. You will require a lid, when not using the IPA the container should be closed or it will rapidly evaporate. It will gradually evaporate over time anyway but a lid, even one which isn't airtight, will massively slow it down. You can also use any non-clear alternative you like such as opaque plastic, metal or ceramic, however it's best to be able to see everything from the outside. Keep in mind you will need multiple containers, at least a second for water, and use the empty water one or have a third for filtering the first one into when recycling the IPA.
In place of a regular container, some may use an ultrasonic cleaner instead, the ultrasonic vibrations can help give a more thorough clean than simply soaking and giving it a shake in a container. Never use the heating function on an ultrasonic cleaner with IPA or other flammable liquid in it, and always be careful regardless as even without using the heating there is still potential for static electricity or something else to spark a reaction. Another (although unnecessarily inconvenient and messy, might as well just use a regular container because it won't save you any time) option is to have plain water in the ultrasonic cleaner, and to place the print in a plastic bag of IPA (or other) which is then placed in the water. The ultrasonic vibrations should transfer just fine into the bag as well, without any risk of flammability or resin contamination of the liquid in the cleaner itself. This would only be suitable for small prints. Another solution I've seen if you really want those ultrasonic vibrations is to use a regular container of IPA first, then after that place in the ultrasonic cleaner with just water, handy as water should always be the last liquid to touch your print anyway.
And of course there are commercially available Wash & Cure machines which theoretically sort all of this out for you... Except do they? It only takes a couple of minutes to properly clean a print in a regular old container, so does a machine save you time? No. Effort? Honestly no, you still have to put it in and take it out yourself, the only difference is with a container you need to give the print a bit of a shake in the liquid for a few seconds rather than being spun in the machine. And the biggest fault, a machine like this will do absolutely nothing for the interior of a hollow print, a hollow print must be repeatedly filled agitated and drained through the drain holes, which can only be achieved manually. There's also size, for solid miniature sized prints yeah I can say a machine like this would be convenient, but even though we have recently gotten a couple medium sized versions of these machines for medium prints like the Saturn and Mono X, prints which make use of that size will typically be hollow, which again these machines don't help with cleaning the interior at all. I can't ignore the fact that these machines also include the curing function which is indeed quite useful and adds a lot of value, however how many prints which utilize the vertical height of the printer are able to stand up on their own after support removal (which obviously is always done before curing) so that they can sit on the turntable inside that limited space to be cured? Only about half of mine.
Printer/Work Location & Light?
I've already covered location in terms of safety, but there is another aspect to consider, and that is of course sunlight. Resin is hardened by UV light, and that includes sunlight. At no point during the process of working on your prints up until curing do you want any direct or indirect sunlight on your prints or near your printer/wash/resin. That window or cover on your printer isn't some UV-proof magical barrier, it's basically coloured plastic which only helps against soft indirect light. Your resin, printer and wash should always be in shadow/darkness away from any source of sunlight and lit with artificial light. Your workspace may be a desk or table next to a window, while you're working on your prints at this workspace during the day those windows must be covered and the light blocked as completely as possible, no thin curtains which just diffuse the light or something like that. I've left in-progress prints on my desk overnight to find that the indirect light reflected off the wall from the thin sliver of sunlight coming through the edge of the covered windows half cured them, making the post-support removal clean-up more difficult. I've heard of indirect sunlight from an overhead vent curing resin over the entire interior of a printer, or a print being removed and passing through a moment of sunlight on the way to the wash, only for the excess resin not being able to be cleaned off because it was partially cured to the print, ruining it. All of this also applies to the UV light used in your curing box/station, which is why it's best to keep it enclosed and contained.
Angling Models?
So there's a very common suggestion out there 'angle the model back 45° before supporting', I guess it's meant to be a good starting point for absolute beginners so they remember to not print straight up but it is definitely far too much of an angle which will result in loss of detail, higher suction forces in humanoid shapes due to larger cross-sectional area, and more damage to your print from unnecessary supports as a result of increased overhang. I print professionally and I always start at 15° back and adjust from there, but usually not further than 20°. The biggest reason to do this angling of the model is first to shift the focus of support contact points away from the front of the model which is the most visible, second to help avoid supports which both start and end on the model itself, third to reduce the chance of or avoid flat surfaces being parallel to the FEP as an angled surface is easier to print and support, fourth to avoid large cross-sectional area during printing on horizontally natured models.
There can be a potential downside to printing on an angle or a part of a print just naturally being on an angle, which sometimes presents itself on long or wide thin objects like discs, bases for figures/statues/miniatures in particular, as well as things like sword blades or guns. The suction force of each layer being pulled up leaves tension behind along the length of the object which isn't released until the supports are removed and stop holding it in place, once that happens the tension causes the object to curve up. This can be completely avoided by printing these parts separately, vertically. But if that isn't an option and there is a part affected by this try to flatten it out while it is curing using heavy objects to hold down the edges, or with things like sword blades brush on some liquid resin and cure it after moving it to a straight position, I once weighted the tip of a shotgun barrel with a paperclip and a magnet to straighten it while it was curing.
Build Plate Adhesion?
Build plate adhesion is how well the initial layers of the print stick to the build plate, these layers have to hold the entire weight of the finished print as well as hold against the suction forces of every single layer as it is pulled off the FEP. So it needs to be good. The easiest way to increase adhesion is to simply increase your bottom exposure times, how long the bottom layers on the build plate are exposed to UV light, this varies depending on your machine and whether you're using a mono screen but generally your bottom exposure should be 6-10x your regular exposure. Another thing to do is to make sure you're always using a raft (unless printing directly on the plate), the larger the surface area the stronger the overall adhesion will be in addition to rafts helping with many other things including making it easier to remove the print from the build plate once it is done. A small print also means a small raft, you can also increase the size of the raft itself on a small print to increase its adhesion. Lift speed also plays a significant role in suction forces, therefore it is possible that having a lift speed which is too high is causing your issues, try reducing it. If you find that your adhesion has been reduced lately then check your build plate is level and z-axis start is the same, it may have drifted over time which happened to me after about a year and had to be completely relevelled. Another thing is if you have a smooth build plate, give the surface some texture, sand it or sandblast it if possible, rough it up and give the initial layers something to hold onto. One last thing, always clean the bottom surface of the build plate between prints (properly using IPA not just wiping off the resin), a clean surface has better adhesion.
Something else I've seen come up occasionally is when someone has a print with multiple pieces on it and the large ones print fine but the small ones fail to adhere and get stuck to the FEP. Large pieces have higher adhesion because the raft has a larger surface area on the build plate. Sometimes a small or thin piece doesn't quite have enough surface area on the plate to overcome the suction, in fact this happened to me just on my last print when printing a vertical base, which meant a long thin raft on the build plate which failed at the widest point of the base (which has the most suction). There are two clear things to do in this situation, first you can manually increase the size of the raft with the 'area ratio %' (that's what it's called in Chitubox, I don't know about Lychee) to increase its surface area, a second option is to move the small piece close enough to the large one that their rafts merge into one, that way the small piece will share the adhesion of the large one.
Using a Raft?
I absolutely recommend always using a raft. A raft creates one unified area where all the supports for a model reach the build plate. One single large surface to adhere to the build plate. It is amazing and it solves or helps avoid so many issues one might otherwise have. It helps build plate adhesion as a larger surface has a stronger bond, and it means each support shares that same strong bond rather than relying on its own small area. It makes prints easier to remove as you simply have to pop off the raft and all the supports remain intact where they are, the entire print from raft to model is one piece you can pick up by the raft or stand on the raft without disturbing anything else. Having to remove a print with individual supports can easily damage the print by tearing off supports as some are moved and others aren't, or during cleaning, and you have to hold it by the model itself which can cause even more damage. Unless printing directly on the build plate, always use a raft. I personally use a very thin raft just 5 layers thick which gives all the benefits while using very little resin.
Layer Height and Pixel Density?
Layer height is how thick each layer is. Generally the lower the layer height the smoother the result and detail, but longer the print will take as it means more layers to print. The default is 0.05mm, and this is perfect for most things, an ideal balance of speed and detail with fantastic results. However if you're printing particularly small things like miniatures or jewellery or keycaps etc then you'll want thinner layers, 0.025 is good, or even lower as most printers can go down to an extreme 0.01. When decreasing the layer height you must also adjust your exposure time settings to compensate, it isn't a 1:1 ratio, so cutting the layer height in half doesn't mean cutting your exposure in half, more like a quarter to a third, you will need to experiment. As mentioned, this will increase print time, half the layer height will create twice the layers, even with adjusted exposure that can mean close to double the print time as the lift times between layers don't change. Although for those with Mono screens it will still be very fast.
That isn't the only consideration to detail however. Pixel density is the other big factor in detail, lower layer heights won't help if you have a relatively low pixel density because the horizontal detail won't match the vertical (the pixels are larger than the layer height) and it'll still look bad. It's why you don't use large format printers to print miniatures as the large screen has larger pixels at the same resolution. As extreme high resolution screens continue to be developed (4K screens for tiny printers like the Sonic Mini 4K, and 8K screen in the large format Sonic Mega 8K for example) this will become less of an issue. The higher the density the better the detail at a small scale, or up really close on a larger scale.
How Long Does a Screen Last?
As you know, the LCD screen in a resin printer underneath the vat is a consumable, and must be replaced at the end of its life. Every screen is different, it comes down to luck how short or long your screen's life will be so the best you will get is an estimated average range of print time before it starts showing signs of failure. Regular LCD screens are being phased out in favour of superior Mono screens, however more people are still using regular screens than Mono as printers are expensive so most can't just buy a new Mono printer, including myself as the promised upgrade kit for my printer isn't available yet. Those regular screens have an average life of 400-500 hours, which can vary greatly. My first two screens lasted around 300 hours, which sucked, my current screen is a rare mythical unicorn which has lasted 1500 and refuses to die. I don't have experience with Mono screens, but their average life is supposed to be 1000-1500 hours, and considering they print more than twice as fast you can look at it as getting at least 4 times more printing out of one screen than a regular LCD. Amazing, and I'm jealous.
Notes: First, the print hours are just that, total hours spent printing, not hours of the screen being exposed on each layer as some theorise it should be. Expecting customers to perform a ton of math would be ridiculous, but it's easy to keep track of general print time so that's what it is. Second, different screens don't just last different lengths of time they also behave differently, I've had to adjust my settings for each of the three screens I've had, so be prepared for that.
Chitubox or Lychee Slicer?
Let's get this out of the way, the default software which comes with your printer is probably trash (unless it's one of these two), you shouldn't use it*. And when it comes to these two mostly it is a personal preference choice, try both of them on the same model and see which one you like the feel of as they're both free after all, neither one is better than the other, they're very similar each with strengths and weaknesses. That being said sometimes it makes more sense to choose one over the other, for example at the time of this writing Anycubic printers do not have native Chitubox support, while many other printers like Elegoo, Peopoly, and Phrozen do. Whichever you choose it will likely have a profile for your printer already made so load that as a starting point. It also must be said that you do not have to do everything in the same slicer, you like the way one hollows better than another? Hollow in one, support in the other, same goes for supporting or slicing, export your supported model from one and simply slice it in a different slicer. There are a lot of fools complaining about being 'locked' into a specific slicer, they really are NOT, all it means is that the final sliced file must be a specific format but nothing before that point is 'locked' at all. *the exception being sometimes for slicing only. Photon Workshop has fantastic AA processing so do all your supporting in something else then slice it in PW for the best AA.
Difficulty Compared to FDM Printing?
When it comes to using the machine itself, much much easier, resin printers are simple machines with essentially one moving part, and are pretty much plug and play. The two biggest factors in a successful print are the supports and slicer settings, neither of which have anything to do with the machine. However unlike FDM printing, resin printing involves a large amount of post-processing of the prints, as well as working with multiple toxic liquids which give off toxic fumes. Safety and location of the printer is much more of a consideration.
Scaling STL Models?
I often see people requesting help to find models at a certain size, such as the particular scale they plan to print at (32mm minis for example). This should be obvious, but models are digital and unless it's pre-supported you can very simply increase or decrease the size of a model to whatever you want it to be right there in your slicer. You can use percentages or input a specific measurement for one of the axis. So don't worry about finding something in a specific size, it doesn't matter. Large models can be printed small, and small models can be printed large, in fact the models from most big miniature file creators are more than detailed enough to be printed as statues at 10x their size.
Where To Find STL Models?
Everybody has heard of Thingiverse, but the search system is broken, will seemingly never be fixed, and obviously you aren't really going to get the best models for free. Yeggi is an STL specific search engine which can be very useful and includes Thingiverse and Cults3D in its results. Etsy can be a surprising gold mine of great models and always worth visiting. Patreon subscriptions also provide some of the best models out there and a good list of these can be found at stltop.com, though it is a miniature specific list (always remember any model can be scaled as large as you like, you don't need to print them as miniatures). Additionally for most Patreons the models from previous months can be found either at MyMiniFactory (which has plenty of non-patreon stuff too) or another place linked on their page. You can always search Patreon itself too, and of course there's simply Google which is useful if you know specifically what you're searching for.
Which Resin Should I Use?
There are many types of resin out there from many different manufacturers. There's standard resin for general printing, plant-based resin which is a type of standard resin manufactured with fewer man-made components, water-washable resin which is another standard resin which can be cleaned with water, tough/ABS-like resin which is extra strong/hard, flexible resin which is flexible once cured, transparent resin which is clear, wax resin for wax casting, and more. You may have uses for any one of these, though keep in mind that any resin which is not a standard or standard transparent resin will be more expensive. They're all pretty much self-explanatory. The 'holy mix' as it is known, is tough/ABS-like resin mixed with roughly 10% flexible resin, this is ideal for it's superior strength as well as ability to flex a little instead of immediately snapping. It is expensive so while perfect for miniatures, for larger prints it's more of a money is no object option. Using different types of resins may require some adjustments to your exposure and other settings, in my experience they are quite minor. Slightly less exposure for transparent, slightly more for tough etc.
Different brands of resin are another matter entirely, there are regular brands, premium brands, and budget brands from places like alibaba etc. Differences are relatively minor and can include things such as general strength, ability to hold subtle detail, and adhesion. You can't really go wrong with any name brand though, changing between brands may require some small adjustments to your settings as they use slightly different formulas but you won't by any means need a complete overhaul, just use whatever settings you already were to start with and adjust from there. I have not use a bunch of different resin brands etc so I don't feel I can make any recommendations.
Least Toxic/Dangerous Resin?
None. It doesn't matter if they're regular, flexible, tough, transparent, low odour, plant based, whatever else, they're all toxic and give off toxic fumes, and all need to be used with proper safety precautions at all times. This isn't play-doh, it's liquid plastic.
Screen Protector?
Some screens come with screen protectors already applied, some don't, and some people install their own. Should you? It depends, they're not necessary at all but they definitely can save you a lot of grief if things go wrong. Most importantly and primarily, if resin leaks or spills onto the screen while it is in use. The way this resin cures onto the screen makes it damn near impossible to remove, if you don't have a protector you essentially are forced to replace the screen which is a large expense, but if you do have one you can simply peel it off and dispose of it, voila problem solved. Either go without from that point on or replace it. I've never had to do this myself however typically a manufacturer does not supply replacement screen protectors, or any at all if the screen doesn't come with one, so you'll have to do research into what to use for this however I have seen people using protectors made for tablets or large phones, cutting them to size for their screen. You may be wondering at this point what the chances are of a leak or spill seeping onto the screen, and honestly it's very low, after printing multiple times a week for close to two years it hasn't happened to me, but it always could for some reason or another at any time, just one clumsy movement or one moment of weakness in a part of the FEP.
There are additional considerations to be aware of with Mono screens. They have a polarization film applied to them which is necessary for them to function, and some people have mistaken this film for a screen protector and removed it after a resin leak or even while installing the screen. Removing it makes the screen useless and it will have to be replaced, there have been many attempts but I have yet to see someone successfully replace this film themselves, you don't want to make this mistake.
PTFE Treatment on the FEP?
This is a controversial topic, the idea is that using a PTFE liquid repellent on the FEP, such as Rain-X will help reduce the suction forces while printing, thus reducing the chance of the print or part of the print becoming stuck to the FEP. There is zero evidence that it has any positive effect, I've tried it and didn't notice any difference compared to without it (although I wasn't having adhesion issues in the first place), nor is there any evidence that it has any negative effect, so try it if you like but don't expect anything. Bottom line, if you're having adhesion issues it almost certainly isn't because of the FEP which is designed to do what it does and that's not where you should be looking, where you should be looking is your build plate adhesion and supports, it's their job to hold the print against the suction forces of the print being pulled off the FEP.
Digital Kitbashing/Editing STL Models?
A lot of the time you may not find exactly what you're looking for, and there are options for that such as making it yourself or hiring someone else to, but there's a good chance you don't want to spend the money or learn yourself, in that case it's likely that you have seen all the aspects you're looking for in other models, just not together in one model. Digital kitbashing is exactly like IRL kitbashing, take pieces from different models and join them together to create something new. This is even easier digitally, say you want an unarmed female warrior monk with rabbit ears, you may not be able to find that but what you can find is a female warrior monk, and rabbit ears you like on a different model. Using an editing program like the free Blender, simply slice those rabbit ears off that other model, and attach them to the warrior monk, sizing and placing them appropriately. The monk model you liked has a weapon? Slice it out, the hands gripping the weapon will probably look like closed fists after which is all good, or remove the hands too and do the same thing as the ears, add in some other unarmed hands you like. Move the position of the arms a little to make the pose look more natural if you like. You can also use the methods to remove or add bases etc to a model. I won't get into specifics on how to do all this, I don't use Blender and it's likely you don't have the paid software I use, but there are plenty of resources out there for learning the basics of something like Blender in particular Youtube videos are very useful.
Note: Miniatures are typically printed solid, so in that case it won't matter, but if you're kitbashing a model intended to be printed hollow you will have to make sure it is a unified boolean mesh so there is no intersecting or interior geometry where different models or parts were joined. Again, I don't know how to do this in something like Blender but I know the tools exist for it so I'm sure you could find out how.
Pre-supported Models?
You may find that many models, particularly those from miniature patreons, have pre-supported options. If you're intending to print them at the size they come pre-supported then this can be a real time saver, but you may have also seen many complaints about pre-supported models. Fact is the majority of this pre-supporting is done by professionals, there are actually groups out there whose job it is to support models for printing and they're paid to do it by creators. Obviously they know what they're doing, however a lot of the time these supports are not very forgiving, they're designed to create a minimum amount of clean-up on the print after support removal, with small tolerances and near perfect printing conditions on a near perfectly calibrated printer in mind. That doesn't really reflect reality. For that reason they are not guaranteed to print perfectly or not fail, don't expect that. And expect it even less if you're printing a pre-supported model from somewhere like Thingiverse which was likely done by the uploader of the model. When in doubt, just do your own supports, I always do.
Stronger Resin/Prints?
3D printed resin is known for being relatively brittle compared to something like traditional injection molded plastic. This is particularly true of small thin prints like miniatures. For stronger prints you need stronger resin, and there are specialty resins out there, 'tough' or 'ABS-like' resins which are much harder than regular resin. However strength doesn't only come from hardness, regular resin can be cured quite hard indeed, it also comes from the ability to flex without snapping. This is where specialty flexible resins come in, it is reported that the best results for strong prints come from mixing a small amount of flexible resin with tough resin (roughly 10% flexible, but I've heard of some using a higher ratio), giving it both hardness and a small amount of flex so that it can bend instead of snap under a reasonable amount of force. Resins like these cost roughly twice as much as regular resin, so you do have to pay for those stronger prints. When it comes to miniatures, something like 28/32mm miniatures costs cents each to print anyway so no matter what you're saving a ton of money compared to buying them, and the stronger prints could be well worth the trouble.
Large Solid Prints?
If you don't care about the price of all the extra resin being used then printing solid won't make much of a difference to you other than having to have stronger supports to handle the extra weight and suction forces, as well as ensuring excellent build plate adhesion. In my experience consumer level printers don't like to print solid, and can have layer separation issues due to the higher suction caused by solid layers, but if you find it isn't an issue for you then it's all good. Some people worry about the interior resin of a solid print because unless you're using transparent resin UV light will never reach it during curing. Technically all the resin inside a solid print is just that, already solid, not completely hardened but solid all the same, resin can't become less cured or solid, just cure the outside so it's nice and hard like you usually would, but maybe give it a bit extra. Most don't have much experience at larger than miniature sizes, but I do and 28mm miniatures times of a few minutes like most suggest won't even come close to cutting it, go for an hour at least, the deeper you get the better, there's no such thing as too much after all. The increased weight can also be a bit of a detriment, the print falling over for example would suffer more force and have a higher chance of parts breaking off, improper handling would also have a higher chance of causing damage due to the increased weight, as I've mentioned in another article, it's good practice to mostly only pick up prints from the main body and that goes double for larger solid prints.
Printing Directly on Build Plate?
Can you? Technically yes, but it isn't recommended. Remember those bottom exposure times for the bottom layers so they stick to the build plate? That's just purposeful over-exposure, and those over-exposed layers are going to cause a bulge where your model touches the build plate. You can maybe work around that by only having a single bottom exposure layer for example, but risk lower build plate adhesion and higher chance of failure because of it. That's not all, there is a known phenomenon of layer separation occurring when a simple object such as a box is printed directly on the build plate, where the bottom surface transitions to just the side walls, even if you have drain holes positioned right where this transition is. The print will usually not fail, but there will be separation, holes, thin areas, and possible some warping along that transition line. It's even happened to me when I printed a large hollow bust directly on the build plate. Another issue can be any other surfaces higher up the print which are parallel to the build plate, again layer separation, an entire flat layer trying to print at once from nothing, even with lots of supports, doesn't usually end too well. Lastly, a print printed directly on the build plate won't be as thin or flexible as a raft is, and this can make it more difficult to remove.
What To Do If I Get Resin On Me?
There's not much you can do other than removing it asap, wipe it off, clean the area with clean IPA, the wash the area with soap and hope you don't get a rash. It's also possible to get resin contaminated IPA or wash liquid on you, wash the area with soap. If some wash splashes or flicks into your eye, all you can do is wash/flush out your eye with water. If you have a particularly bad reaction to contact with resin, such as an allergic one, consider visiting a doctor and/or calling your local helpline for poisons etc. Early on when I had an exposure to resin and had an allergic reaction it caused an extremely itchy rash over almost half my body (from contacting just my hand), taking anti-allergy pills and repeatedly rubbing aloe vera gel onto the rash (as recommended by my doctor) helped a lot until it subsided over a week later. Not a fun time.
How To Make a 3D Model Printable?
Let's say you have a 3D model you've made, or digitally kitbashed or downloaded etc which is not already prepared for printing, what do you need to do to make it printable? I can't give specific steps as I don't use Blender or any other free popular editor, however these are the things to keep in mind. 1) Each piece or part of the model must be solid with thickness and no holes (a 2D plane won't print, they're common on extracted video game models which people often try to use for printing). 2) Each piece/part must be touching and intersecting another part of the whole, with no gaps where they contact (any gap can create a pocket inside the model after making it boolean which will hinder hollowing and create a place for liquid resin to be trapped even if not hollowed), so that the end result will be one mesh. 3) You need to make it one unified boolean mesh with no interior geometry, essentially fusing all the exterior geometry into one mesh with nothing inside (any interior geometry will mess up any hollowing). A google/youtube search should be easy enough to find out how to do these things. Also if the polycount is high you should decimate the model, every 1 mb of .stl size equals roughly 20,000 polygons, you will rarely need any model no matter how detailed to be more than 1-2 million polygons. Fun fact, an entire level/map including all interior and exterior detail in Doom 2016 was roughly 30 million polygons, is your model as detailed as an entire level? Probably not lol so if you've ended up with something like a 1GB .stl file it's time to go back and decimate.
Software/Learning 3D Modelling & Sculpting?
I often see questions like 'what software is good for a beginner to learn sculpting?' and the answer is that there is none. A beginner simply uses fewer of the tools that someone experienced would in the same software and there's no such thing as an easy 3D modelling/sculpting application. What matters is simply which software you choose to put the time into to learn. Personally I'm just into sculpting so I can't comment much on CAD for traditionally functional parts etc, the general consensus there is Fusion 360. However sculpting isn't so simple. There are two real choices, Blender and ZBrush, most choose Blender because it is free and powerful and can do many things other than sculpting. ZBrush isn't free and pretty much only does sculpting, but it is by far the best software out there for that purpose. There is a stripped down free version of ZBrush though called ZBrush Core Mini, and a less stripped down low priced version, you can give that a try to see if you like using it or find it more intuitive than Blender for sculpting, the potential problem being that those versions may not have some functions or plugins necessary for making sculpts printable or exporting as .stls, but that could be done in a secondary program anyway such as Blender. You'll want to stick with either one or the other for sculpting itself, Blender is not a stepping stone to ZBrush, as Blender is a traditional style software and ZBrush is fundamentally different to everything else out there in how it works and how it is navigated. That is why I as someone who started directly with ZBrush find Blender very difficult and unintuitive to navigate, meanwhile someone who started with Blender and learnt that may say the same about ZBrush when trying it. The core principles of sculpting are universal, but when it comes to actually using the software to switch between these two is essentially having to start over from scratch so choose wisely. Both have a huge amount of youtube videos and resources for learning, although Blender being free does mean it has more.
So you've chosen the software you want to learn, what next? People often get stuck at this point, how should they practice, what tutorials should they search for etc. Well first what you need to understand is that all 3D sculpting is 3D sculpting, you do not need to be looking specifically for sculpting models meant for 3D printing, or miniatures or anything like that. Making a model printable is the last step, everything before that is regular old sculpting the same as anything else with the exception of having to exaggerate detail so it shows up on the print better and making sure you don't make details or parts which are going to be too thin when printed. So any youtube videos etc for learning sculpting in general is all that you need and you'll be able to find everything that you need if you don't include terms like 'printing' or 'miniature' in your search which you'll find almost nothing for. I'm personally a huge proponent of learning in the deep end, basically just start trying to do whatever it is you're learning sculpting to do, dive right in, when you don't know how to do something specific research how to do it then keep going. There is no one video or resource which can tell you exactly how to sculpt a model from beginning to end in the way you want while covering every single tool or technique being used. It isn't possible, don't think for a second you can find that. What you can find is videos etc on how to use each individual tool or technique that you may find you need, and when you're starting, first watching a video on the basics of navigating the software and how to use the most basic tools will help a lot. I spent 3 weeks sculpting my first model, and only 3 days on my second, once you get past that first hump you essentially have all the basic skills you need as a base to continue learning and improving, which you will do, I still figure out and learn new techniques regularly two years later. Don't be afraid to try things and experiment, you have an undo button. Some people may prefer starting with guided tutorials etc, but I find that people lose motivation just doing something random in order to learn, when you're working on what you want to create and want to see the end result for then you'll keep pushing until you get there. Make no mistake it will take weeks at least until you get the first sculpt you're happy with, and all sculpting is time consuming, it is not for the impatient.
I Want To Print a Model Ripped From a Video Game?
Not gonna lie to you, it's technically possible yes, but it's tough with a lot of work involved and results nowhere near as good as what you're probably expecting. Why is that? Because video games are essentially optical illusions and what you're seeing is not the reality, there isn't some amazing model of that character in there which looks like it came straight out of a collector's edition box like some imagine. Not even close. Let's skip over the actual ripping part because every game is different, it's not easy and I don't know all that much about it. Assume you already have the models or got them from someone. Those models will look like crap, like they came straight off a Playstation 1. The game engine renders them in such a way which makes them look smooth and like they have depth etc, but in reality they're extremely simple and blocky. All the detail you see in the game are textures, which are images mapped onto the model and rendered in different ways making it look like it's not an image mapped onto a blocky model like a projector screen. So you have this blocky model with no detail, fine you can work with that you'll paint on the detail after it's printed, just smooth it out a bit so it's not so blocky and export it right? Well, not unless you want to print a T-pose or it's an object, so now you have to pose it, which means either rigging it with a skeleton so that you can then move parts of it, or using another method to manually move and rotate parts of it until it's posed, but then you can export it right? Not right actually, because they are nowhere near a printable state, those clothes you see, the hair/fur, anything which hangs or dangles, probably not 3D objects. 2D planes with a partially transparent image mapped to them. All that matters is how you, the player, will see the model in the game, and not see, those arms? They're cut off just inside the sleeve of the shirt, the sleeve which may be a single sided 2D plane. So you've got to do everything that's in the 'How To Make a 3D Model Printable?' section, everything needs to be a solid 3D model, it all needs to intersect, and then be made boolean. Great, you've done that, now you export right? Sure, now you can export one single very low detail basic posed model. Not saying it couldn't be worth it to the right person, and there are some small but dedicated communities which do this for the sake of miniature tabletop games, but it sure is a lot to do for little in the way of results, might be better to just learn how to model/sculpt yourself and be able to re-create anything you like exactly how you want it.
Here is a link to an example image of how game models are made (https://imgur.com/a/GM0YYua), as you can see in the top half, that wireframe is the polygons, that's how blocky a game model is and what it looks like (without the colour) when it is extracted because 3D printing uses only raw geometry, as you can see all the detail you see in the game is actually half a dozen layers of textures with different functions projected on top of that. That is how real-time assets work, the image on the bottom left is how the model up top looks rendered in-engine with all those layers shown on the right enabled.
Finally here is a direct comparison (https://imgur.com/nUO37sm) on the left is a Locust Drone in Gears of War 3 as it appears in the game, and the right is the raw model of it I found ripped from the game. Yeah.
Printing
Signs of a Dying Screen?
As you know, screens are a consumable with a limited life before they must be replaced. The most common way for a screen to die is dead pixels, black spots on the screen which no longer expose and so create holes through the print. Which is likely how you'll find out it's happening, at which point you should remove the vat and build plate and do a full exposure on the screen to see where the black spots are. You can continue to print using this screen if you don't have a replacement on hand yet, just place your prints around the spots, however the spots will continue to grow larger and more will come the more you use the screen until there is no usable space left.
Another way a screen will die is leafing. My second screen suffered from bad leafing late in its life. Leafing is when there are areas of the screen always being slightly exposed, curing a thin layer of resin continuously, this thin layer will attach to supports and the print itself periodically creating 'leaves' of resin up along them. Or if there was nothing to pull them off, simply leave behind a cured patch of resin on the FEP after the print is done. Mostly these are harmless and can simply be pulled off, however they will get worse over time growing in size and thickness until they start affecting the print itself, causing chunks to be taken out like a failed support. And that's how a screen like this will die if it doesn't get black spots first, it will simply become unusable because any print will be ruined by destructive leafing.
I'm sure there are others, I'll add them when I know more about them!
How Much To Fill The Vat?
Filling the vat with resin doesn't need to be complicated at all, in fact it is ridiculously easy, fill the vat with 50% more resin than you know the print will use, done and you will never have an issue. I've seen people try to measure out a specific amount of resin in millilitres based on what the slicer says will be used etc, but obviously the printer can't print if there isn't a layer of resin covering the entire FEP, so that's extra, and all that resin cleaned off the print and wiped off the build plate after is also extra, and you don't want to risk running out so you need extra for safety too. Filling the vat more than you need to won't affect anything, and may even save your ass. A typical print for me may be around 200ml, so I'll fill about 300ml, and I use 1L bottles so that means I'll just pour out what feels like 1/3 of the bottle, it's not a science. Another thing to remember is that technically you can fill the vat almost to the top, leaving a gap about the thickness of the build plate, and it won't overflow or anything. I only do this when I have a huge print using up to 750ml of resin so I can avoid adding resin mid-print. The vat in some printers can have quite a low official fill mark/height and can usually be at least doubled, don't be afraid to ignore it for a larger print.
Adding Resin Mid-Print?
Generally for hollow prints you should always be able to fill the vat enough to last the entire print, here's a tip, you can fill the vat high enough that there's a gap at the top only about the width of the build plate and it won't overflow. However say that for whatever reason you do need to add more resin to a print before it has finished, what's the best way to do that? Most importantly, the resin you are adding needs to be warmer than the resin already in the machine. The one time I didn't do this my entire print failed from that point onward, it was a complete disaster. The easiest way to warm up the resin is to place the resin bottle in hot water which reaches about half way up the bottle, for 5-10 minutes. There's no agreement on when the best time to add it is, but one would assume that pausing the print, adding it, then resuming the print would be the best way. Personally I pour it in while it is curing a layer and have never had issues with that. The last option is while it is lifting/lowering between layers however the problem with that is that in my thinking the force of the current of the new resin pouring in could move any supports or thin pieces as they come down to the FEP, resulting in a layer shift. That being said, things like a layer shift are always a risk when adding resin mid-print, so it is always best practice to avoid having to do it at all.
Temperature While Printing?
There is no question that the higher your ambient temperature the better, the optimal temperature range for resin is roughly 20-35C, it likes to be warm! Which is not a problem during summer. But what about the colder months? Here's where it can get a little controversial, many will argue that you should absolutely stay above 20C or something like that, but you know what? It's completely unnecessary, and my own extensive experience has backed that up. I have routinely printed through two winters now, at lows of 5-10C ambient temp in a completely uninsulated space through the night. Without a single problem. Sure, the resin feels thicker, and the bottom exposure needs to be cranked up a bit, but otherwise it hasn't made any difference at all to my prints or performance of the printer, or cleaning, or curing. Does that mean it's a guarantee that you could too? Well no, different printers and non-textured build plates could find it more difficult, but it is certainly not at all a necessity to be above a certain temperature like some make it out to be. After all, we don't all have the funds or equipment or other necessities to heat our printers or the space they are in. That being said, if your temperatures are going to be below 10C, heating is something you should be looking into, if you live somewhere cold enough to get snow, it will be a requirement.
So, clearly I have no experience with actually heating a printer as it isn't necessary where I live even in winter, so I can only mention a couple of things about that. First, some larger printers have space for a small internal heater to be installed or modded in, this will keep the interior/resin warm and is a good economical option. Another option is to heat the space around the printer to raise the ambient temperature, using a small space heater or other, to make this economical do it inside an enclosure of some sort, you can even use something like a grow tent (often the printer may already be in an enclosure anyway for ventilation), this way you only have to heat a small space. It's best to get the heating as uniform as possible so one side of the vat isn't colder than the other. Another option particularly for small printers is simply placing it on top of a heating pad such as is used for reptile tanks etc. I have also seen for larger prints with metal vats upgraded heated vats. Some people have thought of heating the resin (do this by leaving the bottom half of the resin bottle in hot water for 10 mins) before starting the print, and that can be good if you have a heating solution for the duration of the print but is completely useless if you don't, the heat will dissipate and the resin will go cold again in a matter of minutes.
Something else to keep in mind, in addition to adjusting bottom exposure times in colder temperatures, it's possible that the resin having lower viscosity (being more liquid) in warmer temperatures could slightly increase the softness of the resin (like how hot water softens it for support removal) and therefore adhesion to supports if your exposure times and contact depth are dialled in really tight with little margin for variation. If you start suffering more frequent failures in the warmer months then consider adjusting your exposure settings and/or contact depth a little higher to compensate.
When To Replace The FEP Film?
As a beginner you may get nervous about the FEP and treat it a bit preciously but in fact it can take a lot of punishment and still perform exactly as intended, it certainly doesn't need to look perfect and that little scratch, dent or bit of cloudiness isn't going to do anything. Unless there's a hole or some other similarly major damage it will be just fine for a long while. Now there isn't any hard and fast rule as to when to replace your FEP, before mono screens came about common practice was to replace it when you replace your screen and that was just fine. But now mono screens have such long lifespans that is no longer frequent enough and chances are you'll have to replace it twice when using a mono screen, once when replacing the screen and again half-way through its average lifespan. Certainly before it reaches 1000 hours of print time. So for regular screens, when it is replaced, for mono screens also when it is replaced but additionally at around 750-1000 hours print time (assuming average 1500-2000 hour lifespan for mono screens). You will know a FEP really needs to be changed when the cleaned surface no longer feels slick to the touch, but rough. This is a good time to mention that you should not clean your FEP with paper towel, it creates micro scratches on the surface, submerge the vat in IPA and rub with your gloved fingers to clean off the resin, after removing from the IPA use a quality microfibre cloth to dry the FEP.
FEP sheets are usually available from resellers or the manufacturer directly cut to suit your vat and it's a good idea to always have a spare. If you do some research you'll find that some people opt to make their own cutting them from large sheets or rolls of similar film, to apparently acceptable results, though I don't know any more than that as I use the official sheets for my printer.
What To Do When a Print Fails?
A print failure can come in many forms, failed supports taking out chunks of the print, flat or missing pieces, major layer shifting, the entire print coming off the build plate, or parts of it becoming stuck to the FEP, and more. It is often suggested that the resin be filtered and the vat cleaned after a failure but guess what? There is nothing which happens during a failure which can't or doesn't also happen during a successful print! The success or failure of a print is absolutely no basis for doing a filter/clean cycle. A failure doesn't make it necessary and a success doesn't make it unnecessary, treat every print the same regardless. So let's get down to it, why does this suggestion exist? Loose pieces of cured resin contaminating the liquid resin. When the build plate lowers down to the first layer, the gap between it and the FEP is the thickness of a single layer, so if there is a cured piece of resin thicker than that in the way it will be pushed into the FEP, this can cause damage to the FEP, even a hole, or in an extreme case crack/break the screen itself.
Obviously remove anything from the build plate. Then to start with, between every single print you should use your plastic (or you can specifically get a silicone spatula/scraper just for this) scraper to gently push away the remaining resin side to side and front to back, the same way you would when mixing it back up between prints, you will feel/see any pieces of cured resin on the FEP and if you do simply use the scraper to remove them and lift them out of the vat onto some paper towel to be cured/disposed of later. This goes for any failure involving a part being stuck to the FEP, just pop it off the FEP using your scraper and remove it. It also applies to leafing. And when moving around the resin you will see any loose pieces floating around in it, which is actually quite rare as usually anything would be stuck to the FEP, but if you do just fish it out and you're good to go for your next print.
But when should you actually go through the filter/clean process? Basically, when there are lots of cured pieces of resin floating around, and this only really happens in two cases, an unusual failure or because of leafing. First an unusual failure, due to my build plate losing its levelling over time I had a failure where the raft was partially pulled off the build plate early on, and all the points of the supports stuck to the FEP instead. So what I ended up with was a couple dozen dots of cured resin stuck to the FEP, and there was no way to remove them without becoming a couple dozen small pieces of cured resin floating around which I couldn't possibly find all of, so a filter/clean was necessary. Second is leafing, I've covered leafing elsewhere, mostly it's harmless, it often shows up late in a screen's life, and will leave a small cured patch on the FEP after a print. But when it gets bad and is leaving the semi-cured 'leaves' of its namesake on your prints it can also be leaving similar cured pieces throughout the resin left behind too. You'll see this during your routine check, and when it gets bad enough that there aren't just a couple bits on the FEP or floating around to be removed it's best to just replace the screen because otherwise it'll be filter/clean time between every print and nobody wants that.
Long story short, when a print fails do the same thing as when it succeeds, remove the print from the build plate (and/or FEP if it's a failure), then make sure there aren't any cured pieces left on the FEP or in the resin.
The Supports Printed But The Model Stuck To The FEP?
This is simple, usually the hold of the supports on the model wasn't strong enough compared to the suction force of lifting the layers off the FEP. Either you need more supports, heavier supports, deeper/larger contact depth, lower lift speed, or all of the above. Experiment. Even a heavy support with a tip that's too small and too shallow in contact depth doesn't have any better of a grip than a light support on the model, which is why it's the most important thing to look at. Personally light supports have never worked for me even with miniatures, mediums for me all day erry day son from 35mm up to 350mm. One last thing to check is that you aren't under-exposing your layers, this is actually kinda rare, it's far more common to over-expose, but it is possible to lower your exposure times so much that the bond between the layers is weak and causes failure.
Popping Noise on Each Layer?
It's a little surprising how often this question comes up, and rest assured it is exactly what is meant to happen and means the printer is working. Each layer needs to be pulled off the FEP before a new layer can be made, and this popping sound is just that happening, there is a lot of suction force holding the print to the FEP, so when it releases it slaps back down like a drum skin. Conversely just because you can't hear it doesn't mean it isn't working, the fans on my printer are so loud I never hear it, however I can see the movement of it happening in the resin in the vat like it has been bumped.
There Are Lines on The Print? (Layer Shifts)
These are appropriately called layer shifts, the layer causing the shift didn't line up with the previous layer how it was supposed to. As with most things this is usually a support issue, as in the supports weren't holding the print or part of the print in place strongly enough and more supports were needed to do so. Often it can be replicated when repeating the print without changing the supports. There is also the fact that it often affects only one limb or part of a print before it had reached the point where it joined the rest of the model (at which point it begins sharing the rigidity of the rest of the model and solves the issue, or conversely causes the issue in the other part too if it's bad enough), because only that part lacked supports. This also means it can at times affect only one model in a multi-model print. However shifts like this can also be caused by other things such as bumps or vibrations to the printer itself, incorrectly adding more resin during a print, or a loose or unlevel build plate. And of course sometimes there simply is no explanation, it just happens.
What Is Leafing?
Leafing is when there are areas of the screen always being slightly exposed (which is why it doesn't create a solid block), curing a thin layer of resin continuously, this thin layer will attach to supports and the print itself periodically creating 'leaves' of resin up along them as it is detached and a new layer begins curing. Or if there was nothing to pull them off, simply leave behind a cured patch of resin on the FEP after every print is done. Mostly these are harmless and can simply be pulled off the model or popped off the FEP with your plastic scraper and removed, however they will get worse over time growing in size and thickness until they start affecting the print itself, causing chunks to be taken out like a failed support. And that's how a screen which causes this will die if it doesn't get black spots first, it will simply become unusable because any print will be ruined by destructive leafing. My second screen suffered from bad leafing late in its life, however it isn't uncommon for any screen to suffer from some light leafing late in its life and it will be something else which kills it first.
Shaking Resin?
Here's a quick one, most resin bottles will ask you to shake the resin first before using it. This just means that the resin will separate when static and needs to be mixed up, it doesn't mean you need to literally shake the resin like it's pancake mix! That will create bubbles, and bubbles can affect the print by causing lower build plate adhesion (you will see the all the little dots from the bubbles on the underside of the raft after being removed). Simply repeatedly turn the bottle upside down and back, and swish it around a bit inside in a circular motion, that will be enough.
Nothing Is Printing?
It's a nightmare scenario, your new printer is set up, you start your first print, then some time later when you check back you realise there's nothing on the build plate. Of course this can also happen weeks or months later too, and there are multiple potential causes. The first thing you need to do is determine whether there really is no resin curing at all, or if the print simply isn't sticking to the build plate and you have a cured patch on your FEP at the bottom of the vat. If you do then it's a simple case of increasing your build plate adhesion, I have an article for that. But if nothing is curing then you first have to do an exposure test, this involves exposing the screen without the vat or build plate in the printer so you can see what's going on. Most printers have an exposure calibration test in the menu on the printer itself, this is usually a pattern of some sort, it's also useful to have a sliced file of a flat model which covers the entire build plate and will expose the entire screen at once. Don't see anything? Check that the UV array is working, with my printer there is an area at the back where the light shines through and I can see some of the violet light on the wall behind the printer when the array is on, it may different for yours, worst case pop up the screen without disconnecting the cable so you can see underneath it (without looking directly into the array of course). It's rare to have issues with an array, but if it isn't working it's time to contact support for the manufacturer or supplier of the printer. If it is working then it comes down to the screen or circuitry, either of these can arrive DOA (dead on arrival) or fail prematurely, in fact the power regulating component did for me after just two weeks unfortunately. It's usually the screen though, it could be as simple as a loose cable, or the screen or other part could just be dead, follow any instructions in your manual and then contact support from the manufacturer or supplier.
A Failure in a Multi-Model Print?
Personally, I never stop a multi-model print if one of the models has failed, that's just a waste of resin from the other models you know will finish perfectly well. As long as the failing print isn't falling off the build plate it should be just fine (you do not want part of it to get pressed under another model as it is lowered down between layers, recipe for disaster and even damage to the screen). If it's a partial failure you could even pause the print to remove just that model, so then you won't waste resin printing the remainder of it, just a cured patch on the FEP where it would have been printing which you'll have to pop off after the print.
Some Supports Are Jagged?
You may notice that some supports aren't printing correctly, as if they keep shifting and being build in pieces rather than printing in one clean cylinder. This is something which can affect either thin supports or any support which travels a significant vertical distance for it's size and lacks enough reinforcement (such as cross-bracing) from other nearby supports to keep it in place. It's not easy for thin or long lone (or even pair of) supports to keep themselves straight over long distances, just the surface tension of the liquid resin or displacement caused by large pieces of the print entering the resin as the print is lowered back into the vat can move these supports slightly off course. Either make them thicker, or add supports to support those supports (which is what I do, often supporting light supports with mediums) so the contact area isn't affected.
After Printing
Removing a Print From The Build Plate?
First of all, never use a metal scraper for anything in resin printing, it can very easily damage every single part of your printer and your prints and even yourself as I have seen many sliced open hands online while trying to remove a print with a metal scraper. Always use a plastic scraper. Now, this isn't a universal process, there are many different types of build plates out there and some seem to be more difficult than others. The general idea here is to push the edge of your plastic scraper underneath the edge of the raft (which you're using, right?) or edge of the print directly on the build plate, and pop it off the build plate. For smaller prints it will do just that, pop off almost immediately, for larger prints you will have to go around to every side until the whole thing pops off. Don't try to pry up the whole thing from just one side, it can cause supports to be torn off and damage the print. I do this with the build plate held facing up, when the print pops off it does so gently and remains balanced on the build plate (this can take practice), I can then put down the scraper and gently pick up the print to place into the IPA wash. Sometimes it can take quite an amount of force to get the edge of the scraper under, just come in at a low angle, don't be afraid to give it some power and speed if necessary. For particularly tough prints I've seen it suggested to (after cleaning while it's still on the build plate) freeze the build plate either in the freezer or by dunking into ice water etc, metal shrinks in the cold more than resin does so the difference between them should loosen the seal between them and make it easier, you can also go the opposite direction and dunk the whole thing in hot water to soften the resin.
That's where we come to some build plates being more difficult than others. My prints are always easy to remove even when the raft covers almost the whole surface (and this is a large format printer, there's a lot of surface), and I think it has something to do with having a textured surface from factory. Many build plates come with a smooth polished surface and these can be difficult sometimes, if you find it's regularly difficult to remove prints consider sanding and 'roughing up' your smooth build plate so that it has a textured surface, if you have access to sand blasting, maybe even consider that. However there is another easy option, buy a flex plate such as from Wham Bam to suit your model printer, these are flexible sheets of metal which attach magnetically to your build plate, when the print is done simply remove this sheet and bend it, the prints will pop off easy as that no scraper required.
In some rare cases a print can be particularly difficult to remove from a build plate, and I have seen people damage their build plates in the attempt, I don't have much advice for how to overcome this, but submerging the whole thing in hot water to soften the resin can help, as can using something particularly thin like a razor blade to pry up just one small gap to force the scraper into.
Cleaning/Washing My Print?
This is the superior method for cleaning prints, the best results and fewest potential issues you can get at home. You don't need to be using the same equipment as me, it should all be translatable to other setups, and some aspects have been explored in further detail in other articles such as IPA alternatives, wash containers/machines, resin safety, removing prints, support removal, clean-up, and curing.
It's quite simple really, we need to make sure that the finished print has no liquid resin, resin residue or resin particles on or inside it, no wash residue on or inside it, isn't sticky or tacky, and cures cleanly. How do we do this? Primarily, by ensuring that the last liquid to touch the print is always clean water. But let's start, first remove the print from the build plate and place it into the IPA completely submerging it. When hollow, let the interior fill through the drain holes. Leave it in there for a couple of minutes, I clean the build plate surface and check the vat during this time, it's that quick. Come back and pick up the print (usually by the raft), dunk it in and out of the IPA half a dozen times, shake it under the surface a little if you want. When hollow, invert the model, allow a little of the IPA to drain out through the drain holes, then turn it back and shake the IPA inside, invert it again and let the rest of the IPA drain out, repeat this two more times. Place the print somewhere suitable (I place mine on the inside of the lid of the wash container which is off to the side, so any dripped IPA goes back into the container when I put the lid back on) and give it time to dry while the IPA evaporates, during this time is when I fill a second container with hot tap water and place it on my desk where I do post-processing. Pick the print up again, angle it to let any IPA drip off the raft which may have accumulated, then take it to your hot water and completely submerge it. When hollow, let the interior fill through the drain holes. Leave it for a couple of minutes, during this time is when I will go close the wash container and queue up some music. Post-processing should be done on some sort of water proof non-stick mat, silicone or other. Take out your print and shake the water off. When hollow, also invert and let the water drain out through the drain holes, no need for shaking this time. Remove the supports, keep a folded square of paper towel on hand for dripping water or wet areas. Perform your post-removal clean-up. Then take your model back to the IPA container for its second clean, this second clean will remove anything missed the first time (particularly as a result of the supports getting in the way), as well as anything on the model from the clean-up process as the IPA doesn't let resin stick to itself. Dunk it in and out a few times, then take a soft toothbrush which you've also dunked in the IPA and brush the entire print while holding it above the wash, dunking between large areas, and one final dunk when you're done. When hollow, repeat the IPA fill, shake and drain through the drain holes a couple of times. Once again allow the print to dry while the IPA evaporates, then dunk it in the now-warm water. When hollow, repeat the fill, shake and drain through the drain holes. Finally, give it a quick wash under fresh running cold water before immediately curing. It doesn't get any cleaner than that.
Notes: Up until support removal I wear chemical handling gloves over top of my nitrile gloves, unless I'm taking a break between support removal and clean-up I do not remove the nitrile gloves until the print is curing. For multiple prints I always take the prints out of the wash the same order they went in, so the soak time is consistent. When hollow, for some small cavities just being submerged will not be enough, I keep a large syringe with no tip next to the container, the kind used to feed baby animals, I can use this to blast IPA through a small cavity as typically I will have a small drain hole on each side, and I can do the same with water using a second syringe for the water container.
Removing Supports?
First thing's first, do not pull them off, and always remove supports before curing. Now, with that out of the way submerge the print in hot water for a minute or two to soften the supports, I use hot water as hot as it comes out of the tap. After that it depends on the size of the print, for miniature sized prints many claim having no issues pulling off the small light supports however being miniature sized means there are likely also small/thin parts/details on the print itself which the supports can very well take with them when pulled off. For that reason I would never recommend taking the risk, simply use a scalpel to slice them off where they contact the print. For larger prints use a pair of flush cutters to cut the supports off where they contact the print, then use a scalpel to slice off any small thin supports. It's pretty simple stuff. That being said, try to work in an outside in order, take care of stray supports first which are separated from the major groups, then do the sides and back such as arms and shoulders, starting high, then the front starting at the head, then finally to the lower half of the body and legs, and if there's a base it will be last. Take care when removing groups you have cut free, they can be connected to other clusters of supports and when you try to pull it it way it will pull other supports off the model instead of being removed gently, you can cut the connections between clusters. It goes without saying to be extra careful around delicate areas such as fingers and teeth. If something breaks but is still connected to the support, use some liquid resin to cure it back on before removing the support, it's easier than trying to manually place it there later with tweezers.
Note: Keep your gloves on during support removal, it's very easy for excess resin to remain in areas under dense support or amongst dense supports, if so this will drip onto you or you will touch it. Also you will need them on for the second clean.
Print Clean-Up After Support Removal?
This is both a very important and delicate step. So you've removed the supports, but what they have left behind are small nubs where they contacted the print, marks, rough areas where there were many close together, or even sometimes despite your best efforts, divots or dimples where some material has been pulled out. Cleaning all this up is not what sanding is for, by the time the sanding deals with these everything else around them including all detail will be gone. No, what you need here is precision, you need a scalpel*. Obviously you do this before curing the print while it is still soft, it cuts easily, almost like balsa wood or hard clay. There isn't realistically a way for me to describe the techniques of using the scalpel (maybe I'll add some photos one day), it's just practice, but what you need to do essentially is slice these issues off as cleanly as possible, affecting the print as little as possible. Be gentle, be slow, find the right angle and grip for each slice, slide the blade rather than pushing it, take care where you are holding the print with your other hand as you can accidentally break parts by placing your fingers on them, have good lighting from more than one direction so you can see clearly, you will always miss at least one and notice it later, start from the bottom and work your way up, it's okay to leave most dimples until later as filling them is often a better solution, and finally on some really delicate parts even using a scalpel to remove a nub will cause it to break and in this case it's better to wait until after the print is cured so this part is stronger and then carefully remove the nub. After you're done you'll likely have all sorts of bits and shavings of soft resin on your print, they won't blow or wipe or wash off easily, this is part of what the second clean in my superior cleaning method is for.
Note: Keep your gloves on during support removal and clean-up, it's very easy for excess resin to remain in areas under dense support or amongst dense supports, if so this will drip onto you or you will touch it. Also you will need them on for the second clean anyway.
*I do really mean a scalpel, I know x-acto knives etc are synonymous with hobby crafting but the ones I've had were useless, they didn't hold the blade securely, they were uncomfortable, and required constant tightening. Not so with a scalpel, solid stainless steel grippy handle with a secure blade that will never move and cuts down person sized double walled cardboard boxes to pieces like butter, buying one is in the top 10 decisions I ever made in my life, and now I have multiple around the house. I use a Swann-Morton #4 handle with #27A blades.
How Long To Cure a Print?
The first thing you need to understand is that the limit to curing isn't reached for days, so 'cured' doesn't really mean 'completely cured' it just means as cured as you prefer it to be. I have covered in another article how over-curing is a myth so don't worry about that. In general to be considered cured a print will feel and sound like hard plastic when you tap it with your fingernail, and not leave marks on the surface if you lightly scratch it (if your print is tacky/sticky to the touch before curing as some report then it isn't completely clean, curing is not the solution to that). The smaller the print, such as miniatures, the less time it takes to cure, and conversely large prints need more time. The thickness is also a consideration, miniatures are typically all solid, but larger prints are typically hollow. A common wall thickness to use is 2mm, so when curing you want the entire thickness of that 2mm to cure all the way through, which takes more time than just the surface. It's best to experiment with your own UV lighting setup and your own preferences, I would start with 10 minutes for miniatures and go up from there based on how it feels, personally for large 150mm+ prints I cure for up to an hour as I like them to be harder for strength and also to cure all the way through the walls. Many people on the internet will say 'a couple minutes' to cure a print, but my experience doesn't agree with that, and the manufacturer of the resin I use the most recommends curing for 30 minutes at least to maximise strength.
What about the sun? Well, unlike a UV light it is incredibly inconsistent by comparison so there's no recommendation for that, it works for some, but didn't for me as it took an entire day morning to sunset to cure one print when I tried after my UV light broke. So it's possible, but making a DIY curing chamber or buying a lamp isn't very expensive and is well worth it.
Sealing Drain Holes?
Any part or space which is hollow requires two drain holes (one is useless as it creates a vacuum). After the print is cured and before sanding is the best time to seal these (if you choose to) and the best way to do that is with liquid resin and a small UV torch. You can apply the resin any way you wish, however for the most control I use a flat tipped 5ml syringe. Most resins are viscous enough that the surface tension alone can hold it in place over a hole up to 10mm wide, to do this with the syringe I run the tip around the inside edge of the hole very quickly while pushing out resin and moving toward the centre as more is deposited. Soon enough all the sides will join together with a skin covering the hole, like a bubble. Quickly switch to the UV torch and cure the resin for 30 seconds. Add more layers on top and cure each of them until the surface of where the hole was is flat and matches the surrounding surface of the print. Sand it to make it blend in completely. Another option is to use a filler or putty, such as wood filler or lightweight filler putty like Spakfilla. Resin is the strongest, smoothest solution though, and you already have it conveniently on hand.
Sanding My Print?
Generally I don't recommend sanding the entire print, unless there's a reason the whole surface needs to be very smooth. Generally the layers on a print should be small enough to be unnoticeable, particularly when using lower than standard layer heights for small prints like miniatures. All it will do is sand away the finer details, personally I relegate sanding to the bottom of the base/print, wherever supports have touched the model, sealed drain holes, and sealed seams, all with the purpose of blending them in to be unnoticeable or in the case of the bottom to make it flat. Always wet sand, not only does it make the sandpaper etc last much longer, keeps it and the sanded surface clean, it's also easier to see what you're doing, and you definitely don't want resin dust floating around. There are plenty of options out there for sanding, different grits, tools, files, even printed sanding sticks to attach sandpaper to, or small power tools like Dremels, but I keep it simple and just use a folded twice over square of 800 grit sandpaper/emery cloth held in my fingers (which I dip periodically into a small bowl of water), anything major is sliced off with a scalpel beforehand during clean-up. It's up to you what you want to experiment with. For the bottoms of bases or feet etc I use a random orbital sander with a standard 180 grit disc, it flattens/smooths them right out, you do have to be very careful about how you hold and put pressure on the print though. Always wash off the print with water after sanding. And yes, the print needs to be cured before sanding, an uncured print would feel like trying to sand rubber.
Painting a Resin Print?
There is just one thing to remember, always prime your print before painting, in fact unless it's transparent I don't consider a print to be finished until it is primed as it brings out all the detail and makes it pretty. Most things need to be primed first (unless it's self-priming like some house paints etc) and plastic in particular needs to be. Primer creates a surface that regular paint will strongly adhere to, and stay there over time. I personally use Vallejo Primer through a hobby airbrush, but most any sort of primer will work including the spray cans you can commonly find in hardware or automotive stores etc. It should be mentioned that before priming the print must be completely dry, and the last thing to touch it should have been clean water so there is no residue left behind by whatever cleaning solution you use. After that go ahead and paint it however you would anything else, if you're a beginner the techniques and theory in miniature painting youtube videos are a fantastic resource no matter what size your prints are, channels like Miniac, Midwinter Minis, and others are all pretty great. I would also recommend using hobbyist acrylic paints rather than cheap craft store acrylic paints, they work much better and are designed for it, I use Vallejo paints and all you need is a set of some basic colours as you can mix your own colours from those, no need to go nuts buying 50 colours or anything. Once your print is completely painted it's a good idea to give it a clear coat for protection from handling (not from UV as some seem to think), again I use Vallejo for this, their satin varnish usually, thinned with some airbrush thinner and brushed on produces the best results for me.
Over-Curing?
I don't know where this originated but there are all sorts of beliefs out there about over-curing a print causing damage, cracks, deterioration over time, warping, weakness, and whatever else. It's all wrong, over-curing is a myth. See, I actually tested this over a period of 6 months precisely because none of that made any logical sense. Curing the resin hardens it, curing it more should just make it even harder, and that is indeed exactly what happened in my long-term experiment which is still ongoing to this day and coming up to 1 year. How did I do this?
I left multiple prints outside in the garden in direct sunlight/weather, some painted, unpainted, damaged, undamaged, for 6 months. Within the first week they had all become incredibly hard, a whole different level of hardness compared to what is generally considered 'cured', the undamaged ones otherwise remained the same, and the damage on the others (caused by improper cleaning leading to cracks) accelerated rapidly. So curing will not cause damage, it will only accelerate damage which would happen anyway over a period of months (usually caused by improper cleaning of a hollow print), and it will not cause a print to deteriorate over time, you don't need to keep them away from sunlight, those undamaged prints are still there to this day and other than some dirt looking as great as the day they were printed and feeling as strong as that first week.
What's the catch? The harder a print becomes, the less it is able to flex, which means that if too much force is applied to a part it will simply snap off rather than bend. This applies the most to miniatures because of their size and how thin many parts are, some flex is desirable so they're not easily accidentally broken while being handled. For this reason many will under-cure their miniature prints, however a better solution is to mix in a little flexible resin before printing so that even after printing and curing it will still have some flex. For the absolute strongest results using specialty tough resin with some flexible resin mixed in will give it both extra strength and some flex.
One more thing to consider is transparent uncoloured prints, or potentially white prints as well, they may naturally yellow slightly over time, however curing them for too long can cause this to happen too, keep it in mind.
Cleaning Build Plate?
The bottom surface of the build plate should be cleaned between every print, a clean surface equals good adhesion. I do this while the print/s I've just removed are soaking in the IPA wash, by simply wiping off the resin with a folded sheet of paper towel, spraying the surface with IPA, then wiping it dry with another sheet of paper towel (which I will use to wipe off the resin the next time, reducing paper towel usage). However when changing between resins, replacing your screen or any other major maintenance which will see the build plate kept outside of the printer it will need a complete clean and the best way to do this is to submerge the entire thing in IPA and rub it down with your gloved fingers, then wipe it down all over with paper towel after pulling it out. My wash is large enough to do this, yours might not be in which case a combination of spraying and wiping should get you there. If you're using an alternative which doesn't quickly evaporate or leaves a residue like a Mean Green type solution, it will also need to be washed with water.
Cleaning The Vat?
As a beginner you may get the impression you should clean the vat between every print, I know I did, but that would be a total pain in the ass and the truth is it rarely needs to be cleaned unless you're changing between resins or have a really messy failure. I regularly go a month or two between cleans and I print multiple times a week. So what's the easiest way to clean the vat? First of course you need to remove as much of the resin as you can, pour what's left through a paint filter back into the bottle or a beaker temporarily, use your trusty plastic scraper or silicon spatula to gently help squeegee it off the surface of the FEP while doing this, then wipe away the majority of what's left on the frame of the vat using paper towel whilst avoiding touching the FEP. Submerge the entire vat in IPA and rub it down with your gloved fingers to completely clean. If your wash isn't large enough to do this you can spray it instead. Wipe the frame dry with paper towel and use a quality microfibre cloth to wipe the FEP. Then leave it placed on its side to dry for at least 30 mins just to be on the safe side, you want absolutely no moisture between the FEP and the screen once it is installed back in the printer.
Checking The Vat/Resin Between Prints?
Your process between prints should be the same whether your print was a failure or success, other than a part maybe getting stuck to the FEP there isn't really a difference between them. Obviously remove the print from the build plate first. Between every single print you should use your plastic (or you can specifically get a silicone spatula/scraper just for this like I did) scraper to gently push away the remaining resin side to side and front to back, the same way you would when mixing it back up between prints, you will feel/see any pieces of cured resin on the FEP and if you do simply use the scraper to remove them and lift them out of the vat onto some paper towel to be cured/disposed of later. This goes for any failure involving a part being stuck to the FEP, just pop it off the FEP using your scraper and remove it. It also applies to leafing. And when moving around the resin you will see any loose pieces floating around in it, which is actually quite rare as usually anything would be stuck to the FEP, but if you do just fish it out and you're good to go for your next print. Another option to have a file ready which exposes the entire screen for one longer than average exposure, then you simply peel this sheet off the FEP for a complete clean, you can likely find such files for your model of printer out there already or just slice one yourself, obviously do it without the build plate in. Of course, before actually beginning the next print the remaining resin needs to be mixed up again as it will start to separate, do this with the scraping side to side and front to back after adding in some fresh resin. You can leave resin in the vat for up to 2 weeks easily with no problems, just make sure to mix it well, but if you know you won't be using the printer for like a month or something it's best to just return it to the bottle and do a full clean of the vat and build plate.
It is not necessary to drain/filter the resin and clean the vat between each print, regardless of success or failure, I cover this in detail in my print failure article.
Recycling/Reusing IPA or Alternative?
Your IPA or other wash will eventually get dirty, contaminated with the resin cleaned off the prints. Do you dispose of your wash and start anew? No! Other than it not being easy to dispose of these chemicals, particularly after being contaminated with resin and becoming a toxic cocktail, it's just a waste of money. All you have to do is filter out the resin to 'clean' the wash. But first, when is the wash considered dirty? This mostly comes down to personal preference, some always like their wash to look clean, but for me it's dirty when I can't see the print after the particles settled at the bottom are agitated by the print being dropped in. To be clear, even when this dirty I do not have resin particles stuck to my print when it is removed like I've heard others claim, maybe it's because I'm using 100% IPA, but the purpose of the IPA is that it separates resin from itself, it will not stick to itself and so this doesn't happen. Besides that, if cleaning correctly it will be washed again in water last anyway. So, it's too dirty to me because I want to be able to see what I'm doing, if there are multiple prints in the wash I want to see where they are, and lastly because there is still a chance for some particles to be left inside a hollow print if the wash is particularly dirty.
How to recycle the wash? First, don't put your IPA wash in the sun. I can't speak to other alternatives, but with IPA it will either turn permanently white (and then you can never see anything), or into sludge, nasty toxic sludge which will not evaporate or solidify, or leave a solidified film on the inside surface of your previously clear container. Where did the idea come from to do this and why do so many people try it? Sadly I have no clue, but let me be clear, if you're thinking that surely resin particles need to be 'cured' in order to be filtered out then think again because they filter out just fine as they are! So what you need is your wash container, left long enough for any resin particles to settle to the bottom, and a second container equally as large to filter it into. Carefully with as little movement as possible pour as much of the wash as you can into the second container before the particles at the bottom become agitated and start mixing in, at that point (or just the whole time, although for me it's too heavy to hold the entire 7L wash with one hand when full) start pouring it through the filter instead. I just use the same generic paper paint filters I filter resin with on rare occasion. The remaining resin particles and small amount of wash they're likely mixed with can be put in a small container or tray and left out in a shaded place to evaporate, and then after evaporation placed in the sun for the remaining resin particles to cure before being disposed of. The wash can be returned to the original container and topped up (it will have lost much of its volume over time) with fresh liquid ready to start over again. This should work for all alternatives.
No liquid resin or wash should ever go down the sink or be dumped in the environment.
Disposing of Supports/Failures?
I keep all my supports and bits from clean-up in biodegradable kitchen sized bags while working on my prints. When it's full enough put the bag outside in the sun for a couple hours to cure all the supports before disposing of them in the general waste bin. This is also a good time to mention that all your resin contaminated paper towels should also be cured before being disposed of, I throw mine in the sun for a while also. For failures, not all failures are useless, but if you don't think a failure will have any use at all then there's no point cleaning it or anything so just take it off the printer and put it out in the sun on a paper towel to dispose of later after it's cured. But partially failed prints can sometimes be useful, it can be a damaged alternate version of what you're printing with the right paint job, or it can make an interesting garden ornament after removing the supports.
Cleaning My Tools?
Just a quick mention here, tools which are handled while post-processing can become contaminated with resin, particularly the scalpel may get a bit sticky with residue. All I do is pour/spray a little IPA onto a folded square of paper towel to damp it, and use this to rub the tool clean. The same goes for any other equipment or surface which needs to be cleaned.
Make a Transparent Print Stay Clear?
This is very very simple. A print is made of layers, a surface is only clear when it is smooth, hundreds/thousands of layers is not smooth which is why after being cleaned/dried the surface looks cloudy/frosty. When it is wet those steps between layers are filled with liquid therefore creating a smooth surface, and making it clear. The solution is to fill those steps permanently, which can easily be done with a coat or two of gloss varnish. I use slightly thinned Vallejo Gloss Varnish brushed on.
Will Resin Prints Melt In Hot Temperatures?
No. I've seen this asked a few times, mostly by those coming from FDM printing where it is possible for prints to warp or even melt in hot enough temperatures or extended time in harsh direct sun. This isn't the case with resin, once it is cured heat will not deform it, and neither can it melt or warp, resin burns and no ambient temperature a human can withstand or amount of sunshine can cause that to happen.
My Resin Print Cracked and Leaked?
This can happen days, weeks, even months after a print has been completed, painted and sat on a shelf etc. There is always one cause, improper or incomplete cleaning. Liquid resin, IPA, or both, being trapped inside a hollow print will always inevitably cause cracking and leaking. First of all, pay attention when you hollow the model, you may for example be intending to hollow the body of a character, however it's forearms are large enough that they will be hollowed too, creating separate pockets which need their own drain holes and cleaning. If you don't realise this then liquid resin will be trapped inside and eventually they will crack and leak, ruining the print. Second, always include two drain holes for any hollowed area or pocket, one is useless and creates a vacuum, for small pockets you can use small holes, down to 2mm on opposite sides of the pocket can be effective. Third, use proper cleaning techniques (detailed in another article) to thoroughly and completely clean the interior of the print through these holes, ensuring there isn't a single residue of liquid resin or IPA left behind, the last liquid to flush through should always be clean water. It can be difficult to dry the interior, even after leaving it to air out for days or blowing an airbrush through it, a few drops of water shouldn't affect the print at all.
White Residue on Cured Print?
I've seen this come up plenty of times, and different people say different things but the most frequent being that it's caused by a print not being dry before curing. Here's the thing though, I always cure my prints directly after the second clean when they're dripping wet and I've never had this, if you're cleaning correctly (meaning the last liquid to touch the print is clean water) then this simply shouldn't happen, period. That being said, if you're not cleaning correctly then it absolutely is possible that allowing the print to completely dry before curing could avoid this, although that takes a lot longer than just doing the water step in the cleaning. Also, on non-transparent prints does it actually matter anyway? A print isn't really done until it's primed, which will cover it.
Sticky/Tacky Print?
I've seen plenty of people ask about how to avoid their print being sticky after cleaning, or complaining about it still being sticky after curing. The simple answer is that this should only be caused by one thing, improper cleaning and residue on the surface of the print. A clean print won't be sticky or tacky even before curing, and curing is not the solution to it. A simple example of this is when using liquid resin to seal or repair part of a print, after curing the small area of resin the surface of it will have a thin oily layer, after wiping it with a paper towel damp with IPA it will be clean and dry with no residue. Check out my cleaning and IPA/Alternative articles, and make sure the last liquid to touch a print is always clean water. That being said, maybe there are some resins out there which are this way before curing? No standard, transparent or flexible resin I've ever used though.
Handling My Resin Prints?
Just a quick one here. As you know, resin isn't as strong as we would like it to be, it is known for being relatively brittle when compared to something like injection molded plastic, so in general when handling a print from support removal through to painting what do you keep in mind? Most importantly, keep in mind where you are touching and holding the print, before and after curing. Best practice is to only ever pick up a finished print from the main body or base of the print and if it's tall and skinny try to keep it upright. If you don't know the limits of your resin picking up or holding a print from a limb is a good way to have a limb break off. That's not all though, particularly before the print is cured you will have to hold the print at all sorts of angles for post-processing (and after curing during sanding) and if you accidentally rest your fingers on any delicate or thin part such as spikes, fingers, blades etc, or hold it the wrong way such as sideways putting all the weight on just a limb, there's a good chance you'll break it off. Lastly, they don't handle drops or falls very well, unless you're lucky expect at least one piece to break off from any drop or fall.
Weighting a Hollow Print?
There are a lot of benefits to printing hollow, particularly cost, but also some drawbacks and one of those is the lack of weight. When something is heavy it feels higher quality, that's why they put weights inside the Beats headphones. We know that whether hollow or not the quality of a print is the same, but it isn't necessarily perceived that way when we hold it. So some people like to weight their hollow prints, they want the cost savings etc as well as the quality feeling. There are a few ways to do this. Cavities can be edited into the bottom or feet/base of a model for matching sized weights to be glued or sealed in, this will give weight to the bottom of the print, like a chess pieces, and you'll feel it when you move it. This is also a way to install magnets into a print. For a real heft though the only proper option is to fill the print and seal it. I've seen people use a few different materials for this, first is sand, not dirty sand from your garden mind you, aquarium/fish tank sand, fine sand easy to funnel into a hollow print through a drain hole. Another is metal filings, basically metal sand/dust, it's heavier than sand and is inserted the same way. Related, small metal ball bearings or beads, cleaner and easier to work with but can also be more expensive. A bit of a crazy one I've heard of is using a hot glue gun to sit there and fill the print with hot glue. Or fill the print with cheap craft glue from a big bulk bottle and wait the days it takes to dry. One thing you don't want is anything which expands, the pressure is likely to crack open your print. With any option that isn't glue you'll have to seal up the drain holes after to keep it in.
Assembling, Filling Seams & Repairing Prints?
This is quite similar to sealing drain holes. First, filling seams. When you have a multi-piece print it will inevitably have noticeable seams after being assembled. What I do is first glue the parts together with super glue (I use Tarzan's Grip), then same as drain holes use liquid resin and a small UV torch. The trick with super glue is to have very thin layers on each side and blow on them just a little so they're not completely wet, this way it holds in place within a minute of me pressing the parts together, saving time clamping etc. You can apply the resin any way you wish, however for the most control I use a flat tipped 5ml syringe. Most resins are viscous enough that the surface tension alone can hold it in place over a gap or fairly large length, to do this with the syringe I run the tip around the inside edge while pushing out resin and moving forward, as it is a seam it doesn't really have a start or end, so do it quickly and switch to the UV torch before the resin starts moving deeper into the seam. Cure the resin for 30 seconds, then continue all the way around, and after that add more layers on top and cure each of them until the surface of where the seam was is flat and matches the surrounding surface of the print. Sand it to make it blend in completely (or at least it will seem so after being painted). Another option is to use a filler or putty, such as wood filler or lightweight filler putty like Spakfilla. Resin is the strongest, smoothest solution though, and you already have it conveniently on hand.
What about repairing a print if a piece breaks off? This can be a bit of a judgement call, for something small like a spike or finger, you can easily just hold it in place, add a small amount of liquid resin on the join and cure it back together. But for something larger that isn't going to cut it, you can only cure the resin so deeply into a seam after all, if the gap on all sides is deeper than about 1mm then you should super glue the part into place first, then apply some liquid resin over top and cure it before sanding to blend in. If the print is already painted you might have to just try and get away with the glue, or try some clear resin to make it less noticeable.
What about repairing something really damn small that is too difficult to try and hold with tweezers or something and apply resin or glue to? Here's where it can get interesting, with a bit of practice you can use the combination of liquid resin syringe, UV torch and scalpel to sculpt small undetailed things like a miniature 3D pen. I have created teeth, recreated fingers and toes, even the iron sights of a rifle directly onto the print this way. You can even hold the print up against the edge of the desk on the surface of a non-stick sheet and draw the shape of what you need in resin from where it needs to start, cure the resin, then gently pop it off the surface using the scalpel, after that add more layers and fill it out until it's a full part of the print.
Lines/Patterns on Top Surfaces of Print?
Well yeah, a print is made of layers, you will always be able to see them if you look closely enough, and if part of your print ends on a smooth relatively flat or rounded surface the edges of those layers become spread much further apart. This will make them much more visible and cause the pattern-like effect which looks a bit like a topography map. Nothing you can do about this other than changing the orientation to avoid it, sanding it, or using lower layer heights to reduce it if you aren't already using low layer heights.
Using Heat To Reshape or Cure Resin Prints?
This is different to the worry about melting in the sun I have already addressed, we're talking about using deliberately high temperatures far higher than ambient. I have seen it suggested that applying enough heat to an already cured print can allow you to reshape or change it. This is absolutely false, and I've done the tests to back it up. Here's what you need to understand, the shape resin takes is due to the chemical bonds formed when exposed to UV light, because it is a photopolymer. The only thing which can change that shape is adding/removing material, or external force, the exception being that if you bend part of the print before it is fully cured and keep it that way while it is fully curing it may stay that way as the stronger final bonds are enforced and overpower the initial ones. So what does that all mean? First, it means that heat in no way helps or can contribute to curing, only UV light can do that. Second, it means that heat doesn't make the resin 'soft' in the way 'soft' is typically thought of (malleable), what it actually does is make it temporarily weak without affecting the bonds which already exist as a result of curing.
So, the results. I used a fully cured hollow humanoid print for this. The first test was with boiling water. We know that hot water weakens the resin after printing and helps with removing supports, but it does pretty much nothing to a cured print so I had to step it up to boiling off the bat. I immersed the print in the water for between 30-60 seconds. After it had been removed it was indeed weaker and where before I could not push on the arm and make it bend toward the body now I could. However after letting go it would always return to its original position, holding it in that position while cooling it back down had the same result once I let go, holding it at a more extreme bend while cooling it down resulted in catastrophic failure as the arm simply broke off. I also did scratch, localised force, and cutting tests, the resin behaved exactly the same as hard cured resin in terms of cutting and scratching (barely a mark), and the localised force resulted in snapping far easier and with much less force than when cold. Next I stepped it up once more, by using a heat gun. What it proved was that more heat equals more weakness, at this point the limbs etc will bend down as a result of their own weight without being touched, but never is their form compromised. Any force, whether localised, or even attempting to cut it results in shattering. Not the explosive shattering of a cold print, it simply crumbles into pieces like a soft cheese. Lastly on the highest heat setting I pointed the heat gun at the head of the print, it browned, and then blackened and smoked on the nose where it was closest to the heat. Completely expected because we know that resin burns and doesn't melt. While it was at this temperature I gently pressed on it with the flat side of a pair of scissors and it simply caved in, crumbling to pieces. Later, after everything had cooled back down to room temperature those same shattered pieces were just as strong as before they had been heated.
Conclusion: Heat weakens the integrity of the resin temporarily, but does nothing to weaken the cured bonds determining its surface hardness or shape. There is simply never a reason to heat your cured print.
Food Safe Resin Prints?
Is a resin print after curing food safe at all? No, absolutely not. And this goes for wearable prints with regular skin contact too which should be coated with a protective varnish. But can you make a print food safe? It's true that you can coat a 3D print with a food safe epoxy resin, or food safe latex coating (apparently used for some NSFW prints...) but there is no guarantee that the resin won't react with the coating and break it down over time, eventually exposing the unsafe resin again. Alternatively you can use a resin print to create a mold or a negative for a mold which you can then use to make the mold or object from a food safe material. An example of this is using a 3D print to create a negative, using that negative to create a silicone mold, and then using that mold to cast high detail chocolates. Vacuum forming can be very useful for this process. Another option is using expensive specialty resins, such as wax castable resin which can be used to cast a piece from metal, or ceramic resin which can be fired to result in a ceramic piece which can then be coated in a food safe glaze just as a regular ceramic piece would.