Worm drive

A worm screw driving a worm wheel at 90° — high reduction.

A worm drive meshes a worm (a driving screw) with a worm wheel at 90°. One worm turn advances the wheel by its number of thread starts, so the reduction is wheel teeth ÷ starts (for example 30:1 from a single-start worm and a 30-tooth wheel) — and it’s often self-locking, meaning the wheel can’t back-drive the worm. The worm lies horizontal and the wheel stands on the plate, positioned so their pitch surfaces are tangent. Both are separate editable bodies.

1. Set the module, worm diameter, thread starts, and worm wheel tooth count.
2. Set the pressure angle, worm length, wheel thickness, and bore.
3. Generate: the worm and wheel drop in on crossed axes, meshed.