Buying guide

How to Tension a Timing Belt Correctly

Too loose causes skipped steps; too tight wears bearings and the belt. How to get it right.

Signs of wrong tension

• Too loose: skipped steps, ghosting or layer shifts on 3D printers, visible backlash, belt teeth jumping on the pulley.
• Too tight: motor and idler bearings run hot or noisy, the belt stretches and wears early, the axis feels rough when moved by hand.

A simple method

1. Tighten until there is no visible slack, then pluck the belt. It should give a clear low note, not a dull flop or a high ring.
2. Move the axis by hand over the full travel. It should feel smooth everywhere.
3. On a CoreXY, both belts should sound alike. Re-check after the first hours of use because a new belt settles slightly.

Other causes to check

Pulleys loose on the shaft (tighten the set screw onto the flat), misaligned pulleys, worn idlers, and a belt narrower than the pulley. If the belt is frayed or has lost teeth, replace it. See our length guide to pick the right replacement size.