Squaring a CNC Gantry

If your circles look like ovals, your X and Y axes are likely out of square. This 'racking' is common in dual-motor Y systems.

1. Measure the Diagonals

Move your gantry to the far end. Measure the distance from the front-left corner to the back-right, and vice versa. They must be identical.

2. Physical Adjustment

Loosen the couplings on one Y-axis motor. Manually move that side until the diagonal measurements match.

3. Software Auto-Squaring

If your controller supports it (like GRBL with dual endstops), set $22=1. Use the G28 homing cycle to let the machine find square automatically using independent homing switches.

4. Test Cut

Cut a 100mm square. Measure the diagonals of the cut piece. If they match, your machine is square.