Poor Dimensional Accuracy printing High-Temp Resin on the 3B+

My business recently bought a 3B+ in order to start producing temperature resistant parts, to be used as inserts for Vulcanised Silicone Moulds. Unfortunately, we have had issues relating to warp when using support structures, while printing directly on the build plate yielded parts within a +/- 0.03mm tolerance.

We have followed the recommended post processing procedures for High Temp v2, including using the form wash and cure, and every time we have gotten dimensional inaccuracies ranging from 0.08 to 0.18mm, depending on the orientation.

As someone new to this field, and coming from FDM, I would never expected SLA be so finnicky that our Prusa mks3 is more accurate consistently. I designed a part with internal channels with a diameter of 2.7mm, and was unable to insert a 2.5mm rod into it. The sag is real.

Pictured here is also a different part that deviates from our CAD model by more than 0.15mm

I have never designed parts with SLA printing in mind before, but when we bought similar parts from a 3D printing service we did not have this issue.

Quite frankly, I am dissapointed with this printer. Obviously I wasn’t expecting some plug and play wonder machine that could 100% accurately make parts, but I was also not expecting for us to run into such huge warping issues. +/- 0.05 mm in the xy plane would be acceptable for us, but what we have currently is way too much.

Has anyone else noticed something similar, or run into the same problem? Did I expect too much from this machine, or did we get a defective product? Thank you for any input

There are a few things at play here. I’m going to assume you’re following the recommended post processing instructions.
-Regarding your ID being off by 0.2mm, this may be due to uncured resin being stuck to the walls after the iso bath, but prior to the UV curing process. For these types of channels, they typically need to be manually scrubbed/worked before curing.
-Regarding the curvature being off, the last two build plates I’ve received were not flat, there were +/- 0.005" peaks and valleys on the surface. This had led to inconsistent prints with printing the same model on different sides of the build plate. This may be related to your problem.
-Regarding your dimensions being off, this is likely due to the blooming of the laser curing resin outside of the target volume. This is different for every material. I usually have to run a few test prints and compensate this bloom in CAD by reducing my OD. This only affects the ID/OD of holes, but the center to center accuracy of the features is usually bang on. You can’t simply “shrink” the part in Preform.
-Regarding warping, this is due to the heated curing chamber. Heat just tends to warp thin, flat parts. I would try curing at a low temp.

All in all, I’m incredibly disappointed in my Form 3B. I get more consistent and accurate parts on my $200 Elegoo Mars. I’ve actually been switching back over to that as my daily driver. I even use the Formlabs resin in it and the parts come out even better, and with a quicker print time. Preform sucks. I was trying to print with a small radius directly on the build plate to compensate for the elephant foot effect, and it preform would remove the radius to make a straight 90 deg and not let me change it. The free version of Chitubox did let me do that, it even lets you hollow your model within the program, something preform still doesn’t let you do.

The Form Wash and Cure are handy as hell, I would hold onto them. As for the 3B, up to you. There is no fixing the above issues you are having, just working around them. For the parts that I need to hold a tolerance, I’ve switched to using a desktop CNC.

Hi @praktikant,

Sorry for the late response, but I would advise opening a Support ticket with some details and the .form file so that we can assist in troubleshooting these variances. Thanks!