[Jan Mrázek] is on a quest to make your resin 3D prints more accurate, more functional, and less failure prone. Let’s start off with his recent post on combating resin shrinkage.
When you want a part to have a 35 mm inner diameter, you probably have pretty good reasons, and when you draw a circle in your CAD software, you want a circle to come out in the real world. Resin shrinkage can put a kink in both of these plans. [Jan] identifies three culprits: resin squeezing, resin shrinkage, and exposure bleeding. And these three factors can add up in unexpected ways, so that you’ll get a small reference cube when you print it on its own, but large reference cubes when printed as a group. [Jan]’s article comes with a test piece that’ll help you diagnose what’s going on.
And then it gets complicated! Exposure bleeding depends on your printer and the exposure, but also on the color and UV opacity of the resin. Shrinkage obviously depends on the resin chemistry, but also takes a few days to reach its final state as the print fully cures. Of course, that curing rate depends on temperature as well. [Jan] is just starting to document all the variables, but you can print out his test piece and do your own work as well – you’ll probably have to anyway because of resin-to-resin variation.
While you’re down this rabbit hole, check out [Jan]’s post on viscosity effects and elephant’s foot. If you’re plagued by odd first layers, this is a tremendous resource with one simple takehome lesson: wait longer in the beginning to allow the resin to flow in.
Whether you’re just diving into resin printing, or a seasoned pro, we have a ton of interesting resources. From this article on picking the right resin, to this on whether to use resin or FDM, you have a lot of reading to do. And that’s not even mentioning the gooey Hack Chat last fall with [Andrew Sink], where both he and the crowd dispensed much wisdom.