Print failures with large models

Just looking for some quick help. When I print models under 4cm I have no problems. However, my larger prints fail frequently and as frequently described a flat piece of failed print remains in the resin chamber. If this matters, I recently fine tuned in the z-plane (as recommended by formlabs) because of adherence issues. This instantaneously fixed the problem. I am mainly printing animal bones based off of CTs. Attached is a representative failure. Any recommendations are appreciated.

To me, this looks like a hollow area of the part creates explosive pressure against the walls of the area during PDMS compression, and creates a vaccum against the PDMS on peel. This pressure/vaccum cycle can damage the already printed areas and they structurally fail.

When you move the slicer up can you see it forming sealed hollows @ that height? If so, you can try to either re-orient to minimize these pressurized hollows, or model weep holes into the part to allow it to vent.

I printed a cube 5x5cm) that split in two. I then re-printed it this time automatically orienting it and adding more supports that were much thicker than the last. Printed perfectly after that :slight_smile: so could be a case of heavy model breaking from weak supports during print. Try doubling the support tip size and adding more.

Check the model slice by slice, make sure there is no raw resin within the models geometry as that would cause blowouts and a cascade of failures after.
After failed prints, drain and strain the tank and make sure the pdms is clear from any possibly stuck material.

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