grbl is stepper motor controller firmware for three-axis cnc machines, intended to run on Arduinos with a motor driver add-on board. Engineer in Wonderland cnc-related blogs are indexed here It is the ...

The machine uses a ‘grbl’ controller, which has an Arduino-based circuit that includes multiple outputs, including a powerful 24V pwm signal that is generally used to drive a 60-80W spindle motor..

This is pretty cool, but be careful with grbl. It has software bug on G2/G3 commands with large (20 meters) radius – it just starts jogging forever which might damage CNC hardware.