Ahoy, folks! I purchased an Elegoo Mars 2 resin printer, and this week I've commissioned it and started putting it through its paces. I will use this thread to document my experience with it. First thing's first. The Elegoo Mars 2 is a SLA type resin printer, very different from the FDM printers most commonly used on this forum. I bought a combo on sale for around $300 with printer, wash/cure station, and a small stack of handy bits like filters, funnel, plastic and metal scrapers, etc. The Mars 2 uses a vat of UV-cured resin, with an LCD screen and UV source on the bottom. There is only one moving part, the print bed on the Z axis. To print a part, the print bed moves to a tiny fraction of a millimeter above the bottom of the resin vat. The LCD screen activates to block light from any areas that aren't your part, then the UV light turns on for a few seconds to cure the resin. Since the resin sticks to both the print bed and the resin vat, the printer does a quick up/down motion to break the part free from the bottom, then positions it for the next layer. Activate the LCD screen, flash the UV light, break the part free. Wash, rinse, repeat. Once the part is "done", it needs finishing. I remove the print bed from the printer and place the part in the wash station. A few minutes of washing with isopropyl alcohol and all of the uncured resin is removed. Remove the tub of isopropyl alcohol and the wash/cure station is ready to bathe the finished model in UV light to finish curing the part. And voila, one new part. This method has several significant differences from FDM printing. First, only height affects your print time. It doesn't matter if you're printing one part or a dozen, if they're the same height then the print time is identical. Very helpful for mass production. Second, resins can have very different physical properties from thermoplastics. In the past, resin had a reputation for being very brittle and weak. However, in the last year or so, many new resins have been released including ABS-like, high-strength, rubber-like, extreme toughness, and other specialty products. These can also be mixed to combine desirable properties. Third, SLA printers can achieve extremely fine levels of detail. They have layer thicknesses that are just not possible on an FDM printer, so you can get sub-millimeter details on parts. I intend to use my SLA printer primarily for making small, precision parts such as pumps, cannons, lifeboats, spotlights, small-caliber AAA, and of course gaming miniatures. First impressions: Assembly was *almost* easy. Both the printer and cure/wash station arrived pre-assembled, all I needed to do was unwrap everything, remove the packing foam, level the print bed, and start printing. At least, that's how it was supposed to go. The instructions skipped a couple important steps, but the youtube tutorial I followed warned me and I didn't even slow down. Then I found that the Z axis on the printer was rotated off-center, so the print bed wouldn't actually reach the Z=0 position without hitting one of the resin vat thumb screws. This took about about an hour of research, disassembly, and re-assembly before it was ready. I'm not particularly surprised, it's a pretty cheap printer, after all, and I got it on sale from amazon. I probably got someone else's return because they didn't know how to fix it. Asides from that little speedbump, it was very easy. Next up was adding resin and doing the first print. The moment I popped the lid on the bottle of resin, I was hit by a powerful odor. The reviews are right, this stuff SMELLS. I have a pretty weak sense of smell, and I noticed it quite strongly. I will definitely be relocating this printer or establishing some serious odor control. The test piece, a couple of hollow chess rooks with spirals, text, and other details, came out quite nicely. The cleaning/curing station proved very easy and intuitive to use in both modes, and in just a couple hours (plus 10 minutes of finishing) I had two very fancy chess pieces. Talking with other people who've tried resin printing, the cleaning/curing station is probably just as important as the printer itself. Without such a station, you either have to hand-wash your parts or get a small ultrasonic sink (expensive), and then either cobble together your own UV light source for curing, or leave your parts outside and hope that works. With the station, the entire finishing process is absurdly easy and takes less than 10 minutes. I've started playing around with the slicer program, chitubox. It's very different from Cura or other FDM slicers I've used. Lots of different settings, different capabilities, etc. I've got a lot to learn. Also, different problems, different solutions, and different failure modes. Problems: From what I've read, most folks with SLA printers manage to break a screen every few months. I haven't broken one yet, but I've only got a few prints under my belt. I've also been told that failures tend to compound. A single print failure can leave bits of cured resin in the bottom of the resin vat, potentially cracking a screen or damaging later prints. Pictures: My current (inadequate) setup. The printer and wash/cure station are in a disposable metal tray to catch spills. I will probably move them onto a table in a closet so I can seal away the fumes. I already have a couple of air purifiers with activated charcoal and other filtration mediums on order. A batch of test parts just after the wash step, a destroyer-sized pump that I've printed in ABS before. The resin print certainly looks smoother, plus its transparent so I can see what's happening inside. Now in the curing phase. The LEDs emit two different frequencies of UV, and the plastic cover is a UV-blocker. The plastic table rotates slowly to ensure all sides are evenly cured. Finished parts. Note the printed-in-place #4-40 threads. While I wouldn't trust this particular resin with a high-powered battleship pump, it should be fine for a small destroyer pump.
Welcome to the messy, sticky, and stinky world of SLA. a few notes: Resin tends to warp and get brittle with age. I have many pieces I printed over the years and many have warped from sun exposure and I have had some crumble. Resin parts are a lot more brittle than fdm. Don’t use them for anything load bearing or in a wear situation (gears or threaded parts) Instead of building in threads, I have used heatset inserts and used epoxy/resin to fix them in place. The knurling on the sides helps lock them in place.
What he said : ) Also you may want to explore some of the less toxic resins. I've had good luck using them in my Anycubic Photon S for a while now.
Since I've really just started with my printer, I've got lots of ideas. Hope you don't mind answering a few questions. 1) I have read plenty of warnings about resin getting brittle from sun exposure. I have two questions. Have you tried painting your parts to protect from UV? Are parts inside the hull (pumps, motor mounts, etc) safe without painting? Also, is hot storage (back seat of a car in summer heat) a problem for resin parts? 2) for strength/brittleness/toughness, recent resins offer significant improvements. I just received a bottle of Siraya Tech Blu, one of the higher-performance resins on the market. I'm very curious what resin you guys are using, and for what parts. 3) I love the idea of epoxying in threaded inserts. Any other big-brain tricks I should know about? 4) any tips for gluing resin parts together?
I also have the Elegoo Mars 2 printer. After using it for over a year, I have yet to replace the screen. You can get a screen saver for it, which I did. Here's the current version, I have an older version: https://mach5ive.com/products/mach5ivescreensaver?variant=39972748886069 For the resin, I have tried several. My current mix is 2/3 Blu and 1/3 Elegoo ABS-like. The Elegoo ABS-like by itself was too brittle. It was reasonable right out of the cure station, but I found that it became more brittle as it aged, even when not exposed to sunlight. The Blu by itself is tough, but I trouble with it bridging. It was unable to reproduce the detail needed for my ball chain sprockets to fit correctly. The mix has been the best of both. Below are some of the main parts I'm printing. The sprockets are for driving rudders. One of the cool things about resin is that you have enough resolution to be able to print the servo spline right into the drive sprocket. For the sprocket that goes on the rudder shaft, I have settled on printing a hole for a wheel collar which is pressed in after printing and before curing. A little of the resin is added to lock the wheel collar in place. Initially I designed the rudder sprocket to use a nut insert, just like I do for FDM printed parts. These early sprockets all failed because as you cranked down on the set screw it would just pull the part apart. Pumps are a great fit for the resin printers. My current pump has only three parts. The case is held together with 4-40 screws. I use a tap to make the threads, it is much easier for me than drawing the threads. My rotor is also tapped for the set screw. Since neither of these threaded parts is under a lot of stress, I have not needed thread inserts. To deal with smell of the resin printer, you need to look at your entire build chain. For me, the smell of the printer when printing was pretty minor because the cover keeps most of vapors contained. I run a stand alone filter inside the enclosure, but I don't think it makes much difference: View: https://www.amazon.com/gp/product/B086277CNQ You have some smell as you are loading resin and removing parts, but this is unavoidable. Most of the smell I had was from paper towels that I used to catch resin as I took the part off the build plate and cleaning the resin tray. Initially I just threw the waste towels in the trash and left them there for a week or more. When I took out the trash, the trashcan still had the resin smell to it. I had to set the trashcan outside in the sun for 2 days to get rid of the smell. Now I have a small dedicated trashcan with a lid (3 gallon size, I think). I always take the resin waste out daily to ensure that it doesn't permeate the shop. I also put a UV light inside the top of the trashcan. This cures some of the waste resin on the paper towels and gloves and also cuts down on the smell. One other problem you might encounter is low resin temperature. My shop is in the basement and is around 65 degrees year round. This ended up being too cold for printing and most of my first prints were total failures. I ended up building a heater for inside the printer. Now I just set the temperature and let it the printer pre-heat for 30-60 minutes. Resins like Blu are very viscous at temps below 75 degrees. While not really practical in our hobby, you can go crazy with details for your ship. Do you want oars in your life rafts? No problem. All of these parts are 144 scale, printed on my printer.
well I'm already learning the limitations of resin. Some of my parts came out well, others not so much. Almost all of the small threaded holes were utterly unusable. Unfortunately Big Gun magazines are probably not on the menu for this printer. I'll stick with FDM for those. Probably will use resin for the small parts like pistons, though. Still need to try Fast Gun cannons, though. Also gotta try props and lifeboats. Edit: would love to see how to use threaded inserts with resin parts. That would be very helpful. Edit 2: what ratio of Blu and ABS-like are you using?
RCE answered really well so Ill add in my personal experience from owning a resin printer for 2 years. We never mind sharing our knowledge and experiences. So all of the parts that Ive had issues with were not painted and typically were flat or thin parts. The minis I usually print are always painted and they are in good shape after 2 years. Cranes for my Bismarck warped within days and shattered themselves. My original Bismarck turrets looked great for a day.. then cracks formed. I havent noticed any heat deformation AFTER curing. During, yeah, things will warp. there are a lot of different resin types. I use Sainsmart ABS Like to print my D&D mini’s. I havent tried different types as I don’t use it all that often to justify the extra costs of some of the higher impact resins. That said, I havent seen a 3DP UV resin that beats FDM as far as impact strength. Wet sanding. Wet sanding. Wet sanding. Resin dust is horrible. Keep some old HTPE jugs (milk or water jugs) to pour your used IPA in. Then stick that jug in the sun for a few days. Itll cure a good majority of the suspended resin and make it fall out of suspension. Pour it through a filter into another container. This way you can get more wash life out of the IPA. Use the same resin! When I glue my minis to their bases or repairing, I dip a toothpick in the resin and dab it on the part. Stick it in the sun and you’re all glued!
I don’t have any pics of parts Ive made as it was a while ago and I was using the parts for mechanical (brackets for my CNC router) and they have long since broke. however, you can see this guy briefly adding the inserts into his prints during the build montage. View: https://youtu.be/1iF_qicnkB4
OK folks, need a little help here. I'm finding some partially cured resin left in small holes. While I can often just drill out the hole to clean it up and salvage the part, I'd rather not have these problems in the first place. Plus it could be catastrophic to have unwanted material buildup inside the ammo ramps of a BIC-style cannon. I have not noticed any particular trend about the cause of material buildup. Any tips?
Make sure your PET film is CLEAN. If there are finger prints, the UV light will be diffused and cause partial curing of masked areas.
You also have to make sure there are both drain holes at the bottom and vent holes at the top (build plate side) to facilitate drainage. If you are confident in your drains, then you may need to add a pause to allow the resin to drain after each layer. Every time the build plate plunges into the resin, it essentially pumps liquid resin into any void in the part. The first time I printed a stock BIC, the opening in the bottom of the gun was partially full of resin. I first added a drain at the bottom but I also had to add a vent before it would drain out. The ramps drained OK and BBs rolled though easily.
Any tips for maintaining the resin vat warm during winter? Despite my best efforts, the smell has forced me to remove the resin printer to the garage, and it gets pretty darned cold out there.
I started with a space heater about 3' away from the printer. It worked, but used a lot more power than necessary. I ended up building a PTC heater that sits inside the printer and heats the whole enclosure. I upgraded the printer power supply to a 10A 12V and used the printer power switch to send power to the heater. I also put bubble insulation around the printer lid to keep all that heat in there. I used this source to start my heater design: https://hackaday.com/2021/04/01/off-the-shelf-parts-make-a-tidy-heater-for-resin-printer/ I published the parts for my heater on thingiverse if anyone wants to try them: https://www.thingiverse.com/thing:5607537
