We received several questions in the comment section of our Kickstarter regarding infill.

Hugues Laliberte:

"@Kudo3d, you said below:
We do not print solid models that has large cross-sectional area because it is very hard to control the bulk shrinkage.
I'm still not very clear on the possibility to use infill. I need strong parts, i cannot print them hollow. So if you say large cross sectional sections will shrink, then it's better to print with 0.2 or 0.4 infill, with a hexagonal pattern like we do for FDM ? Is this possible or not ? I would like you guys to expand on this topic, maybe in the forum. Not all users are printing small figures. You have a large print area, so we need to use it to print large parts too, with dimensional accuracy and solidity."



Peerless Design:

"@kudo and Hughes- I definitely can't be printing completely hollow parts for my business, was the abs test piece that I sent you printed solid hollow or some type of infill? This could be a problem for me.

Albert T

@ Kudo3D, regarding questions posted by @ Peerless Design and @ Hugues Laliberte, I think it may be a good idea to define "large cross-sectional area". How large can a cross-section be before hollowing it out. Furthermore... hollow structure can still have a very thick wall as long as the overall cross-section is still not above the "limit", right? Also, I think infill is difficult for SLA because it does not allow the resin to drain effectively... Can you pioneer a slicer that both allow infill and will automatically create holes / path to drain excessive resin trapped within? :P

The Answer:

It depends mostly on the resin. We have to measure the shrinkage for these low cost resins and then do test printings for solid, larger models. The user can purchase low shrinkage resin from name brands. A large, solid model could require hundreds of milliliters of resin, which can be very expensive.