Updated 15 June 2019
So this story starts with multiple weeks of headaches, failed prints, a completed destroyed PDMS vat, and almost two liters of wasted resin. I scoured the forums on a near daily basis but never got anywhere, just more failed prints, wasted resin, and frustration.
This post is a culmination of everything I learned. Throwing out the useless information, and providing a more unified starting point that I was unable to find in the existing documentation and forum posts. And I by no means mean any offense to the great people here; I wouldn’t have this knowledge if not for a combination of my own trial and error and the kind people of the forums. I merely mean that the good information is too scattered and too cluttered with bad information.
Getting Started: My Moai Setup
- I have the Moai 130, purchased Q1 2019, before the SD card reader was updated to a ribbon cable.
- Peopoly’s heater module, placed in the upper chamber, back left corner.
- Standard build plate
- PDMS vat (Resurfaced)
- Software: PreForm, ChiTuBox, Asura
I’m using the latest Peopoly recommended settings as of 20 May 2019, with one exception.
- I have modified the Z Reset Position during my modified leveling process (see below)
Peopoly’s instructions for laser calibration are fine. No issues here, this part of the process was smooth and needs no re-writing.
- If you’re using the FEP vat, you must use the Easy Level build plate. The standard build plate will overflow the resin in the FEP vat.
- If you’re using the Easy Level build plate, loosen the bolts, fully extend the plate, and retighten the bolts, then follow the instructions below. Don’t bother trying to use the bolts to do leveling since it’s basically impossible to get even pressure on all four corners while also attempting to tighten the bolts.
- In order to properly level, you will need digital calipers. Unfortunately there’s no way around this.
Level your machine as best you can first. This just helps the overall print quality and doesn’t make a huge difference to calibration or leveling, but it does help a bit with the resin flow. I recommend using a cross check (or T-Level) bubble level for this.
Remove both the left and right panels from the Moai to gain access to the vat adjustments; having both sides off makes it much easier.
Keeping in mind that the PDMS vat’s default Z Reset is 1877, I recommend starting at 1870; especially if you’ve resurfaced your vat since the PDMS thickness itself can vary from vat to vat and a resurface will certainly be a different thickness. A good thing to know here is that the Z Reset is increments of 1/10th of a millimeter.
Once you set the Z Reset, the build plate should lower into position. Using the reflections of the build plate on the PDMS layer, you can eyeball how level your vat is. The build plate and its reflection should form perfectly parallel lines with one another. Use the included socket driver to tweak the vat corners until the reflection is as close to parallel as possible.
Once you’re visibly level, slowly increase your Z Reset until the bed just barely touches the PDMS. Then back it off 1-2 points. Recheck your level by checking for the perfectly parallel reflection.
Now it’s time to fine tune! Print the DIY four corners test file, you should be within 0.5mm on all four corners. If all four pillars are within 0.2mm of each other, then all you need to do is adjust your Z Reset by an amount that will put all four into the 10.6mm to 10.8mm range.
For instance if your DIY test comes out with the following A=10.80, B=10.82, C=10.98, D=10.94, the worst offender is 0.2mm too high, you would increase the Z Reset by 2, reprinting should give the results A=10.60, B=10.62, C=10.78, D=10.74 which will produce beautiful prints.
If the corners are NOT within 0.2mm of each other, first increase the Z Reset to make sure none of them are more than 0.5mm off from the recommended 10.6-10.8mm range, then very carefully tweak the tallest corners to lift the vat higher 1/4 turn at a time between tests.
Something to note here: the thinner your layers are, the more critical it becomes to get all four corners as close to each other as possible. 0.2mm variance should work down to 60um and maybe down to 40um, but you’ll probably want tighter tolerances for thinner layers. This means more patience and more test prints to get things perfect.
Ultimately, my Z Reset ended up at 1882 after leveling, and that’s fine because I had resurfaced my vat and I used a more thorough leveling process that threw away faulty assumptions. It’s fine if your Z Reset is different, just make sure you keep track of it somewhere. You can certainly use the Peopoly recommended 1877 and rely entirely on the vat screws, but that method is going to take more work to get perfect leveling.
Supports and Solid Parts
I start by using PreForm from Form Labs to get a good orientation on my parts. Unfortunately there’s no way to export the correctly oriented part as an STL as far as I can find, but I take note of the position before moving on to support generation.
Next, I move over to ChiTuBox. I bring in my model and orient it per PreForm’s suggestion. This tends to be a pretty solid orientation. I then use ChiTuBox’s auto-generated supports set to the built-in Thin profile. This works great for smaller models, but you may want to go to the Medium profile for heavier models.
Before moving on, I now go through the layer slider and make sure there’s no small floaty bits left unsupported and I manually add any additional support I feel may be needed. Once that’s done, I export to a new STL file.
Now on to Asura; it’s an okay slicer, but importantly it handles Moai properly so that’s why I go here to finish up. I don’t like printing solid chunks in resin; they stick to the vat and cause excessive suction. So I use Asura’s hollowing function and make walls no thicker than about 5mm (I prefer 2mm where possible).
It’s important to use the hole tool here as well while generating the cavity; 1.5mm holes seem to be perfect. These holes can be anywhere on the model as long as it connects to the internal cavity; they don’t need to be oriented to drain as it prints, so hide them in places where they won’t affect your model’s final function. Since the cavity remains open during the printing, only a small amount will pool up inside the cavity; it can be drained after the printing is completed.
At this point, everything should be calibrated beautifully and printing near perfect. Use IPA and clean/finish the printed parts as recommended by the resin manufacturer. Personally, I use an IPA-safe plastic tub with a mesh stand inside it to place the parts on, then place the whole thing on a magnetic lab stirrer.
Problems I Faced, How I Resolved Them, And Why
Easy Level Build Plate - Plate adhesion was great, but prints would fail after 10-15mm. Unfortunately this plate is nearly impossible to level properly using the bolts because it requires all four corners to have even pressure, and no slipping while you tighten the bolts. Instead, I tried collapsing the plate entirely, but the top bolts were in the way and it ended up heavily cocked to one side. Ultimately I found fully extending the plate worked best, and treating it as a standard build plate from there.
FEP vat - I was experiencing a lot of print failures with the resin adhering to the FEP film and not releasing. As it turned out, the FEP film that was pre-installed was bad. It had a weird rainbow shimmer to it, a bit like the surface of motor oil; I think this may have been caused by heat during shipping? After replacing the film with a new one, the vat was crystal clear and prints stopped sticking to the FEP film.
Temperature - Added Peopoly’s heater - I don’t have a dedicated room I can keep my printer warm in without overheating the whole house. Resins at room temperature were way too thick, so the easy solution was installing Peopoly’s heater. Highly recommended.
Leveling - Peopoly’s leveling guide is tedious to follow and makes too many assumptions about the consistency of their PDMS vats. The FEP vats are easier in this regard, as the thickness is much more consistent. The easy level build plate doesn’t actually make things any easier; if anything it makes problems worse because it can be VERY difficult to get consistent pressure on all four corners while also trying to tighten down the nuts. This ultimately means you have to level the build plate, then ALSO level the vat to fix any slight errors.
PDMS Vat - Resurfaced - After a catastrophic failure of my PDMS vat, I had to resurface the silicone. This involved completely removing the existing silicone, thoroughly cleaning the vat with clean IPA until it was spotless, and then using an inexpensive platinum cure 2-part silicone (QSIL 216). I used a 48hr heated cure for a better finish; This was done inside the Moai with its heater turned on. My replacement PDMS is much stiffer than the original, which is turning out to be a net positive. It’s also resisting damage from the laser better, although I can’t explain why that might be.
Supports - Support generation is a pain in the backside; Cura doesn’t do good supports for SLA on its own, and Asura’s support generation has horrible shaped rafts that you can’t get a blade under. Asura also doesn’t put supports in the correct places; it frequently leaves floating bits that cause print failures. I’ve had to resort to a three application process for orienting the model, generating supports, and slicing.
MORE TO COME: I’ll be updating this guide with additional information as I learn more, I just wanted to get the basics down as quickly as possible for anyone else who may be struggling like I was.