A corner for a touring truck frame built from aluminium T-slot extrusion. Three plywood plates meet at the corner. The post runs through it and the two rails butt into the post.
The plates overlap each other in a cycle. Along each edge, the overlapping plate has a finger at every bolt and the other plate fills the gaps between them. A button-head bolt runs through each finger into a captive hex nut in an oval pocket in the next plate.
Every size is the same script with different parameters. The script stops with an error when a cut collides with another cut, breaks through an edge or comes out narrower than the bit. Its source is touring-truck-frame on GitHub.
Revisions
small-a
October 2026. The test corner: 3-1/4 in plates in 1/4 in ply around single 20 x 20 mm extrusion, so each plate comes out of a 3-1/2 in scrap square. Not cut yet.
Per corner it takes 6 M3 x 20 button heads with M3 nuts, 8 M5 bolts with T-nuts into the slots, and 1 M5 bolt into the post’s end bore.
full-a
September 2026. The full-size corner: 9 x 10 x 8 in, in 7/16 in ply around 3 x 3 in 80/20 3030 extrusion, with 3 bolts along each edge. Cut on the laser, and it went great.
Per corner it takes 9 #10-24 x 2 in button heads with hex nuts to join the plates, and 5/16-18 bolts with 15-series T-nuts into the extrusion slots. The four holes in the bottom plate’s corner go into the post’s tapped end bores.
Cut files, in inches: bottom.dxf, side.dxf, front.dxf, and all three side by side in parts.svg. The model is corner.step, in mm. They’re the files from commit 2063c2c.
