Customizable mitre box for extrusions (e.g., OpenBeam)

thingiverse

A mitre box designed to cut OpenBeam extrusions or similar with simplicity, inspired by Terence Tam's design but without the need for a hold-down clamp. The base and box pieces are printed together using ABS at .3mm layer height with 60% infill, glued with acetone-based glue. M3 screw guide pegs, 45mm long and partially threaded, are used for precise cuts; clean the holes before inserting the screws. Add friction tape to the bottom surfaces for better contact with the beam and work surface. A standard .025" thick, 24TPI bi-metal blade is recommended, but a 32TPI blade can also be used if available. STL files are included for OpenBeam and 2" ratchet clamps. For angled cuts, T-clamps or using the beam's slots may be necessary to avoid blade interference with clamps. Adjustable screw diameter is possible by downloading the SCAD file. The original design did not include M3 screw pegs, but they were added after experiencing up to 0.8mm off-perpendicular cuts without them. Sample cuts show good repeatability and a nice finish requiring minimal filing.