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).
Grey Pro is good but it’s dimensional accuracy can be off. I like the surface quality of it and it’s good in some cases but the true champ for me is tough 1500.
I looked at Tough 1500 and 2000 but decided to go with GP based on material properties and sales rep’s recommendation because my parts are tiny. The Tough series doesn’t reproduce my level of detail, according to him. Dimensional accuracy with parts that are only .020" thick and 1/4" long is less critical than detail replication.
These 2 pix show 2 S scale (3/16" to the foot) ladders I printed Thursday night in GreyPro at 50 micron layers. 1 photo shows a part twisted 180 degrees along its axis. The other photo shows the 2nd part bent 90 over itself with half of the supports attached.
The ladder rungs are .014" diameter in the photo without supports and .016" in the one with supports. The part with no supports rec’d a 5 minute UV post cure; the other part got two 5-minute cycles because I needed to determine what another 5 minutes would do.
I’ve successfully printed another part with a 1.40" length of .016" diameter “pipe”. I also printed .018 and .020 and each part measured within .001" of the CAD geometry (likely due to how layers are stacked in the build).
I am VERY impressed with this material. The ladders also have L-shaped mounting brackets with scale-sized rivet heads (.012" diameter x .008" tall) that are visible on the parts but are hidden in the images by my fingers. Gotta hold on to them somewhere!
