I ran a few very small, fragile model railroad parts thru GreyPro last night on my Form3 and the results are amazing. My Formlabs sales rep exchanged several emails with me as we narrowed the many resin options to what would likely work best for me. I compared material specs for several resins at the same time. Since my parts have VERY thin cross-sections (ladder rungs are .016" diameter), Clear resin was not suitable because parts were far too brittle. Based on GreyPro’s specs, the “green state” closely matched Polypropylene which is my target material.
The 2 test ladders were printed parallel and perpendicular to the platform. The ladder built parallel had some ovality in the rungs, which was expected. Still, the Z dimension was .018" while the X/Y was .016" diameter which matched the CAD model exactly. All parts, including ladders, were printed at 50 microns. All rivet heads built cleanly in both orientations. Amazingly, both ladders in the green state could be twisted 180 degrees end-to-end with no “setting” or breakage. After two 5-minutes rounds in the UV oven, I could twist them 90 degrees and return to straight condition with no damage. Truly a great resin for my application. I highly recommend it for modelers. Being grey-tinted is an added bonus because I can see all of the detail without having to spritz with auto primer after curing.
GreyPro will become my go-to resin for thin, fragile parts but I’ll retain Clear for rubber mold patterns because that’s the best for detail replication that I’ve found (and been told).