FEP Vat failure


This just shows how very important it is to have a heater installed. Peopoly has a heater for sale in the store.


I wouldn’t be surprised if the issues here are temperature related. I’m not totally convinced the supports in the photos are done correctly for the FEP vat either.


What is the “ideal” temp for resins to be sitting in the vat? I have a heater keeping the chamer at 30-35c and I’m still getting failures… Less, but still fails.

I’m guessing since the vat is aluminum, it’s going to stay a LOT cooler than a plastic or similar. I’ve been testing with measuring the actual resin temps and would really appreciate knowing the ideal temps.

Can they be too hot?

If the chamber is 40-45… 50-55?.. Is that TOO hot? Is there a temperature that we should stay away from? I’m tempted to just try running at 50c to see what happens. I’ve changed every single setting possible.

Releveled multiple times.
Tilt speeds down to 3…
Over powered laser
Under powered laser
Peopoly FEP
.05, .1 and .2 FEP
Every kind of peopoly resin and other brands

I can’t afford to buy a PDMS vat every single week… I run prints 24-7, FEP is awesome in theory, but I can’t get a single totally solid print off of it.


Ideal is between 25-30C. Higher and you may trigger polymerization throughout the resin. FEP is much stickier than PDMS, so you should probably look to your peel motor speeds and z-follows.

As for replacing PDMS vats on a weekly basis: if that is not hyperbole, then there is a problem with your models, resin, or settings. A typical PDMS vat should last through 2 liters of resin, barring issues. Which resins and what laser settings are you using? Are your models very large? Also, it is possible to recover a damaged PDMS vat. This means both removing polymerized resin and repouring the PDMS.


I’ve done all that. So far only higher resin temps and supports generated in Asura are helping, I am going to do a full post on solving these FEP issues when I’m done testing.

For one, I am running the Moai 24/7 and currently have 2, so it is very very easy for me to go through a PDMS vat per week, I am using them for production parts as well as functional prototypes. As for recovering the PDMS I literally don’t have the time to do that, so its not an option for me.

So far the FEP is ideal, but I need to find the right film, settings, temps, and fine tune other factors to make sure I don’t get any failed prints. After about a week of testing I am close, it comes down to the air temp inside the printer being warm and consistent, and the resin temp being between 28-32c.

Support generation and the type of supports and base are important too. I am actually pretty impressed so far with Asura and its options.

For now, for people having serious failures like other in this post, use a heater either from peopoly or make one your self like I did, use insulating foil foam pads on the inside of the printer to help regulate the temperature, and keep the chamber between 33-38c (as measured right in the middle of the upper chamber) which seems to keep the resin in the 28-30-32 range depending on color and brand, some seem to hold heat differently. AND use asura for support generation and use a LOT of supports. Coupled obviously with slower PM motor speed.


on the topic for film, please stick with our FEP film as laser SLA printer has much higher requirement for the FEP film than LCD printers. We literally test over 100 films before finding one that is suitable and cost effective.

Temperature is a big factor, 30C will help a lot. Thick support with 1.2 support tip in Asura will help. the dense but tiny LCD style supports are not ideal for SLA printing in general


Yea, I’ve tried. I’ve still got a few of your sheets I got through matterhackers, but switched to a slightly thicker film to try and rule out the film as my issue and so far I am having really good results and they’re about $2/sheet.

And yea, I agree. I really wish the documentation during assembly, setup, and even on the bottles of resin said the ideal temperature range and its importance. That is honestly my biggest complaint with the Moai so far, lack of support, documentation and instructions. It is all so spread out over the forum, wiki and google docs… It takes 10 minutes to find the results I am looking for sometimes because it’ll be written in one place an not another.


thanks for the feedback. wiki is the central for official information so stil with that.

sticker film can produce unpredictable results so keep an eye on it.


Jesse - What FEP are you using?


Price has changed but it’s this stuff, I’ve done about 40 medium sized prints so far and haven’t had any issues, even with the stickier tough resin.


In summary: By heating up the build chamber the chances of a successful print when using a FEP Vat are increased significantly.

I promised to get back on the subject of building an (alternative) heater out
of a 220V 200W 200x200 mm silicone pad.

I have put my post under the “heater-installation” topic:


heating the build plate helps adhesion too. that is why we went with air heating. It is also less dependent on user installation


In case anyone is interested, I have managed to print two of these in a row the first time I used my fep vat - I had struggled using the silicone vats. I have done a sieve of the resin checked the level and am printing my third now

Used Asura for supports. I ended up removing a lot of the auto generated supports and then adding some more of my own where I thought I needed them. It is summer here at the moment so temperatures in the build chamber are generally above 30°C (I sit my printer on top of a couple of brewers heat pads and have a temp controller trying to drive the air in the unit to 40°C. In winter I insulate the whole unit with a couple of boxes over it.


Looks like you have some strange wobbles in the supports? Is everything tightened fully? Might be worth checking everything if not.

Make sure the rep vat doesn’t budge when you try to wiggle it either, one side of mine used to wiggle a little so had to put some tape in it to make it tighter, prints came out better since then.

Also have you found the fep specific firmware settings, peel speed down to 10 etc, if you have normal firmware seeing’s it is more likely to fail


I just tried FEP- VAT, tried to do leveling first with DIY-test…it fails!!!
I am even unable to get a single cylinder on the build plate (using standard build plate), i tried different combinations of Z-reset position from 1812-1822 and PM motor speed from 8 to 12, every time flat pieces comes out under the VAT and nothing on the build plate. Any help???


That aligns with my experience. I’ve found that the FEP vat really needs the resin to be very thin to be reliable.

35C is a good target, 40C is even better. The Peopoly Clear resin seems to print reliably at 30C for me on FEP (I’m also using the self-leveling build plate), but I think that’s because it has no pigments to increase its viscosity. It’s already a pretty thin resin. The Peopoly Black resin, on the other hand, almost consistently fails at 30C on FEP in my experiments, and doesn’t start printing reliably on the entire build area until it reaches at least 35C.

I think that the main reason why you need to thin the resin to work on FEP, where as the PDMS vat will work at lower temperatures and higher viscosities, is that the FEP vat has no elasticity. The PDMS is very squishy, so the print will always slightly indent the surface of the PDMS and create a space that traps a very thin layer of resin consistently. But when printing on the FEP material, which is a hard surface, there’s no chance of this happening. To print successfully on FEP, the resin must be thin enough to rush back into the gaps under the regions being printed before the laser fires to harden the next layer. If the resin isn’t thin enough, then it has a good chance of creating layers that are too thin, causing delamination, bubbling (uncured resin trapped between layers), or complete a failure to print the layer. Failures of these types in the FEP vat are especially common in the shallow region on the left side of the build plate where there’s less resin and, therefore, less physical force to push resin into the gaps.

I think this could actually be fixed with a firmware update. The build plate needs to raise about 10 steps, about 0.1mm, to allow more room for the resin to rush in, and there also needs to be a brief pause (0.5 seconds) before lowering the build plate to print the next layer. This way, we probably would not need to heat up the resin nearly as much, and the chances of getting successful layers might be more consistent across the entire vat.


Getting the standard build plate to work with the FEP vat can be a bit of a nightmare. Your leveling has to be pretty much spot on. It took me a couple of prints with the machine open, manually adjusting the leveling bolts and tweaking the Z-reset position just to get my first partial success. And you’ll probably also have to re-level every time you change out the FEP sheet. And this is why I no longer use the standard build plate.

Bottom line, the self-leveling build plate is the best way to go. The first time I used it, it just worked. It completely eliminates the leveling problem.


At this stage, I am not too concerend about failed supports as the prints are actually fine. I am thinking about going back into asura and removing a whole lot of the support that fail anyway. But as I have a gcode that is working I will not touch it until I have printed everything that I need urgently. Failed support make cleaning up the part far easier!


hi Brian,

Thanks for the detail feedback. It is a good observation and that is why our FEP recommended settings are different than PDMS

The pm reset distance is longer and peel is slower. It has less to do with “resin rushes back” and more to do with not have enough clearance for the fep film to separate from the plate at the left side of the plate. Thinner resin may flow better but also much weaker mechanically and that you will get shrinks and funny breaks. The same Moai FEP vat is now being adapted by Formlabs users on Form1+.

making sure resin is over 25C will help tremedously with printing. PDMS vat is very tolerant of printing practices but with correct settings, >25C print temperature you can get very consistent and for some users cleaner results. @Karim @rozza