First some background. I started at Formlabs last Monday, and while I have extensive experience with FDM 3d Printing, stereolithography (SLA) is a dark art to me. There are LASERS and GOO! Now I’m willing to embrace the idea of a magic box that makes things, but I’d like to know more about how it works and the things it can do.
I figured my options are either to pester the Formlabs engineering staff, or to come to the forums and learn the answers for myself. Also, since I didn’t go to MIT, the engineers can be a bit intimidating.
I’ve always wanted to experiment with thin walled hollow objects, which aren’t really doable on FDM machines.
I started from an older model of mine, the Tachikoma.
The Tachikoma isn’t originally my creation, its a model from the SketchUp 3d Warehouse that I extensively reworked several years ago.
To make the Tachikoma a thin shelled object I used ‘Hollow’ function in Meshmixer.
I used a 1mm wall thickness and a high mesh density and accuracy. I added drain holes on the bottoms of the legs, ends of the arms, and back of the abdomen, places where they won’t be obvious. All of the drain holes are 1mm in diameter.
In PreForm I rotated the Tachikoma backward 70 degrees so that the drain holes in the abdomen are at the lowest point.
The intent is that these two holes will act as vents, letting air into the model so excess resin can escape.
I also turned on Internal Supports to keep the shell from collapsing in on itself.
There won’t be any way to remove these internal supports, but If the Tachikoma was printed in opaque resin they wouldn’t be visible. For this print I am using clear, so I can see if the resin and isopropyl alcohol drain properly.
The final print worked amazingly well.
There where no draining issues, and all the details came out nice and crisp. The print is a bit soft, it flexes when you squeeze it. From what I’ve read, post-curing may help eliminate that by further hardening the resin.
I hope you found my experiment as entertaining as I did.