I want to make some composite beams from styrene parts. I'm trying to figure out whether I have to pre-paint the inside of the H-beam before gluing the web truss on. The parts are Plastruct HFS-4 and OWTS-4. Plastruct_glued_beam_3 by S t e f a n posted Nov 26, 2020 at 6:39 PM Plastruct_glued_beam__2 by S t e f a n posted Nov 26, 2020 at 6:39 PM Plastruct_glued_beam by S t e f a n posted Nov 26, 2020 at 6:39 PM Is that web open enough for rattle can paint to do a decent job on the inside of the H-beam if I paint only after assembly? If I pre-paint, then I have to scrape or sand the paint off the edges of the beam so that the styrene solvent glue works.
I did a test: the problematic area is actually less the bottom of the H channel than the inside facing flange of the open web truss profile. But using these profiles will be way too expensive anyway ($5 per foot!). It seems 3D printing is the way to go, especially if one can fine-tune the resin color, so that no painting (or maybe just a flat seal coat) is needed.
