Warping on models for silicone moulding

Support & Troubleshooting Form 2
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Hi, I have been prototyping (pretty standard product design prototypes) with a Form 2 for almost two years now with great results. It’s an awesome machine and I’ve had no problems with that kind of usage.

A few months ago I’ve been asked to design and print some low reliefs that would be used as masters for a silicone moulding process to make things like pins, keychains and wall plaques
This is the process. I make the master with the 3D printer. We use the master to create the mould and then we cast metal.

Now the problem is that there’s warping in all the models I print. Sometimes there’s so much deformation that we cannot cast the finished part.
The warping is really small when I detach the part but it increases in a few hours. It will warp even if I leave the supports attached. The deformation is increased where there are thin expanses.
Some picture showing the problem:

IMG_20190912_123941
IMG_20190912_1239413120×4160 158 KB
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IMG_20190717_093704
IMG_20190717_0937041920×1440 181 KB
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I used standard standard white and grey resins, high temp and castable wax. All four show warping (high temp shows the least amount of warping but it usually breaks inside the mould)

I read all the topics on the matter and the proposed solution were:

  • Increase the number of supports → it doesn’t seem to make a difference.
  • Make the model thicker → I already do that when it’s possible without changing the client’s design.
  • Orient the model so it’s not parallel to the build plate → Done that, doesn’t seem to help…
  • Someone suggested the warping could be due to temperature changes in the room during the printing process. The office in which the print is located should stay between 22-25 ° but I have no control on the temperatures overnight.
    Usually I print overnight and the models sometimes hang a few hours on the plate before I detach them in the morning. Could that be a problem?
  • I tried to print directly on the build platform. It seems to work but then we see the laser lines on the casted metal…

I’m running out of ideas. Did anybody have a similar problem and figured out a solution?
Should I try another resin? Which one do you suggest?

Thanks and excuse me for the bad english. It’s not my native language. If something is not clear please let me know.

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1/ print the pieces vertically or at a slight angle to the vertical with supports on the back rather than the front.

2/ put the finished, warped, pieces on a solid metal surface and then pour very hot (ie nearly boiling) water over them.

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