MechanicsBasicbacklashplaygearsprecision
Backlash
In 30 secondsThere is a little play between gear teeth. When the direction reverses, the motor turns without moving the output, and the error at the tip grows with the length of the arm.
Also available in: Català · Castellano
The idea
There is clearance between the teeth so they don’t jam. When the direction reverses, the motor turns a little without moving the output. It is measured in degrees.
How much it matters
error at the tip ≈ length × angle (in radians)
Example: 2° (0.035 rad) on a 30 cm arm → 0.3 m × 0.035 ≈ 10 mm.
For a robot that handles objects precisely, it matters; for a leg, less so, although it still affects control.
How to reduce it
Harmonic drive, preload or split gears.
In the demo
Set the slider to 3 or 6° and change direction: the output waits until the teeth touch again.