Pulley / sprocket

A timing-belt pulley or a roller-chain sprocket.

A toothed wheel for belt and chain drives: a timing pulley (GT2 or HTD, with optional guide flanges to keep the belt tracking) or a roller-chain sprocket (ANSI #25–#60).

You pick the standard by name, not by pitch, because pitch alone does not identify a belt or a chain — GT2-3M and HTD-3M are both 3 mm pitch with different tooth depths, and #40 and #41 chain are both 12.7 mm pitch with different roller diameters, so a sprocket cut for one will not seat the other. The name sets the pitch, the outside diameter, the groove depth and the roller seat together.

Those sizes are exact: the pitch diameter from the standard relation (belt PD = teeth × pitch ÷ π, chain PD = pitch ÷ sin(π ÷ teeth)), the pulley outside diameter reduced by the profile’s pitch-line offset so the belt tracks instead of riding on the tooth tips, and the roller seat on the ANSI seating curve. The tooth flank is a straight-sided approximation of the true curved form, so engagement is right in scale and nominal in shape — worth a test print against your specific belt.

Pairs with the gear train family for full drivetrains; stays editable in the property panel.

1. Open the Generate panel from the left sidebar and choose Pulley / sprocket (under Gears & drives).
2. The toothed wheel drops in as one editable part. The parameters open in the Properties panel, where you set them.
3. Pick Timing pulley or Sprocket, then choose the belt profile (GT2 / HTD) or the ANSI chain number.
4. Set the tooth count, bore diameter and width; for a timing pulley, toggle the guide flanges.