Gear train

A line of involute gears that actually mesh, at the right spacing.

The gear train lays out a line of involute gears, each spaced from its neighbour at the correct centre distance so they truly mesh instead of just sitting near each other. Every gear shares the module and pressure angle (required to mesh), and the Properties panel shows the resulting ratio live. Helical gears alternate helix hand down the train so they mesh. The gears are separate printable bodies — print them and mount them on your own shafts.

Backlash is the small deliberate play between meshing teeth, and it is why the train turns after printing. Gears at the exact centre distance with full-depth teeth mesh with *zero* clearance — correct in theory, but a printer lays material slightly oversize, so teeth that only just touch will jam. The default (0.15 mm) suits most FDM prints; raise it toward 0.3 mm for a coarse nozzle or a loose fit, and use 0 only for a display model that never has to rotate.

1. Open the Generate panel from the left sidebar and choose Gear train (under Gears & drives).
2. The gears drop in already spaced to mesh, with the ratio shown. The parameters open in the Properties panel, where you set them.
3. Enter the tooth count of each gear, in mesh order (two or more).
4. Set the shared module, pressure angle, thickness, and optional helix angle and bore.
5. Leave Backlash at its default unless you know you want a tighter or looser mesh — 0 will bind once printed.