Heads up: many models on this page are AI-generated or uploaded untested. They may be misconfigured for the intended application — check the dimensions and tolerances, and verify or edit the model before printing or relying on it.*
Rotating Gondola Line Arm
A 64 x 36 x 6 mm swivel arm from the 'NEMA17 Hanging Wall Polargraph Drawbot' kit (print two). Its 22.8 mm chamfered bore turns freely on the Ballast Gondola Pen Hub's 22.0 mm pen sleeve, so each drive line stays aimed at the pen axis at every hang angle. The line ties off through a 2.5 mm countersunk eyelet 40 mm from the axis, and a 1.5 mm knot groove on the top face seats the knot.
Ballast Trough Screw Lid
This is the 90 mm OD x 3 mm annular lid from the 'NEMA17 Hanging Wall Polargraph Drawbot' kit. It closes the Ballast Gondola Pen Hub's shot trough so the ballast can't fall out. Its 22.6 mm bore slides over the hub's 22.0 mm pen sleeve. A 30 mm OD thrust ring, 2 mm high, gives the two rotating line arms a smooth bearing face. Three M3x8 socket-head screws go through 3.4 mm holes on a 40 mm radius into the hub's M3 heat-set inserts, and six 1.6 mm radial ribs stiffen the plate.
Ballast Gondola Pen Hub
This is the main gondola body for the 'NEMA17 Hanging Wall Polargraph Drawbot' kit. It is a 90 mm dia x 46 mm hub with a 22 mm OD pen sleeve and a 14 mm through-bore that takes pens 8–13.5 mm across. The sleeve sits on the axis of an annular ballast trough, which holds about 120–150 g of shot or coins to give steady pen pressure. The trough is closed by the kit's screw lid, fixed with three M3x8 screws into M3 heat-set inserts (4.0 mm bores) at r = 40 mm. A 3.6 mm slot in the sleeve lets the collar's M3x16 screw clamp the pen, and a 1 mm chamfer on the base helps it glide over paper.