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I have no prior experience with stereolithography 3D printers. For a research application I am considering the SLA approach but I have a more basic question.

I would like to use SLA in order to print porous structures from ice cores. Using X ray tomography I have raw data of very high resolution 3D images of the cores. The idea is to use this information in order to print representations of these cores to perform a diffusion study. Some of these cores come from depths below 50 m thus the snow has compacted in such way that volumes of air are occluded.

My question is if it is possible for SLA printers to print in such enclosed volumes. Imagine for example a solid cube with a gas bubble in the middle. Is that possible for an SLA printer and if yes will the bubble contain air or the liquid resin of the printer?

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    $\begingroup$ I like your question. I don't have an SLA printer. It is somewhat unnatural to have enclosed volumes in an SLA printer. It could be either filled with uncured resin, or, if the size of the opening, the viscosity of the resin, and the draining time per layer are right, perhaps partially filled with air. "Partially" because uncured resin will stick to the inside. It might be later cured in the UV soak process, but I think you lose control of the geometry. $\endgroup$ – cmm Aug 5 '20 at 19:36
  • $\begingroup$ @cmm here is a video of a scan, where you see white think void, black is filled solid material (in the real case ice and in the #D printer case plastic) youtu.be/oTDOVxpl6PU $\endgroup$ – VG_nbi Aug 6 '20 at 15:53
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    $\begingroup$ VERY related: Why is cupping bad in SLA prints? $\endgroup$ – Trish Jan 3 at 22:37
  • $\begingroup$ @Dr.MantisTobbogan - Finally, I posted a meta post on some editing guidelines. $\endgroup$ – Greenonline Jan 4 at 8:55
  • $\begingroup$ yes..but.. practically you'll want to add a pair of vent holes to let the fluid escape (one for air one for fluid) you can have a large void in the print, but you'll need some post-processing to deal with it. You'll first have to drain the bubble, then clean it, then fill it with the gas you want, then seal it. I can't think of a simpler way, but there might be? $\endgroup$ – Diesel Jan 5 at 18:40
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The bubble will contain air, but this will vary by printer. Most resin printers lift the printed part out of the bath slightly after each layer. Some printers, however, don't lift the piece completely out of the bath. This will cause the resin to become entrapped. Once those entrapped pockets of resin are exposed to light, they will also undergo photopolymerization. It may be possible however to program those printers to lift the part completely out of the resin for each layer.

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    $\begingroup$ actually, due to how easy it is and speeding up the print, these days most don't lift it out of the resin vat but just raise it enough to separate it from the build surface. However, it's just a modification of the g-code increasing the raise it over that threshold... or the firmware. $\endgroup$ – Trish Sep 6 '20 at 9:57

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