Post Print Warping


I’m printing a large model in several pieces, 9 total. I have hollowed out the model and given each piece walls of 2.2mm in order to save resin.

The pieces will be glued together after printing to create the complete model so as you can imagine dimensional accuracy is very very important.

I am finding that the prints when they come out of the printer and after the IPA bath are very accurate and fit pretty much perfect with each other, however after a few days (of being in a normal room that gets daylight but no direct sun exposure) they significantly warp. This causes them to not fit together anymore.

As you can imagine it’s very frustrating, since they are coming out of the printer great but then become pretty much unusable because of the warping. They are never exposed to direct sunlight nor post uv cured. Nothing except the IPA bath as recommended in the guidelines. Keeping the prints in a dark room is not ideal either since they need to be used.

Is this issue known about? Is there something different I could be doing in order to avoid the post print warping? (would curing in an uv oven help or hinder for example)

Thanks in advance for your suggestions,

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I produce parts in a similar fashion - I also post cure in a uv steriliser. I store all my prints in a box out of any light until they are ready to be molded, or if they are for a one off piece, glue them together and paint. If your sections are made of very uniform straight sections this could compound your warping problem - prints with organic shapes /curves tend not to wasp so much in my experience.

Thanks for your input @JasonSpiller. I guess that means that warping with natural light is a common thing and unavoidable?

Idon’t post cure my parts on an UV oven, but thinking of doing so. Have you found this helps reduce the warping? If it does please walk me through the logic, as it seems its the UV rays from natural light that cause the warping to begin with. Is is a factor of high concentration of UV for a short amount of time that gets rid of the problem?

Post curing can introduce a bit of warping on its own if it is done unevenly, but will generally significantly improve long term stability.

Note that much of the post print warping can be from water absorption into the part, not necessarily light exposure.

Thanks for chiming in @MaximLobovsky

Is the water absorption due to the IPA bath? If so what are the alternatives?

Can you give us general post-print best practices to minimize warping and maintain dimensional accuracy? I have read the Post Curing Prints support page as well as the white paper o UV curing but these seem to focus on optimizing for other mecahnnical properties, perhaps at the expense of maintaining absolute dimensional accuracy.

(as a quick example, should we leave supports in during the post curing or take them off prior)?

I have not found this topic properly addressed elsewhere.

Your insight would be incredibly helpful.


Water absorption is probably not related to the IPA bath.

To be clear, I am repeating information based on studies of other SL resins. We have not tested the impact of water absorption on our parts and how much of long term warping comes from that.

In general, thorough post curing will increase stability against longer term changes or warping, but there will be some amount of warping during the post cure process itself. Post cure warping can be minimized by even illumination by rotating the part manually or automatically.

I agree that this is an area that we can work to provide more data on.

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For me, it also helps to keep the parts on the support structure as long as possible. I think it’s probably best to cure the parts after the IPA bath, once cured it won’t be able to warp as much.

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