Update: Calibration ruler test file added (in mm). Plots a ruler of 10mm on X and Y axis, using Z axis with a pen. Simulates an axis, drives an RC Servo instead. Want to use a servo in GRBL for the Z axis, but don't want to change your firmware too much? This quick hack is designed as a drop- in replacement for a stepper driver such as the easydriver or Pololu driver. It reads the DIR and STEP signals and converts an internal step counter into PWM for an RC servo. Great for use in existing hardware. No fundamental changes in firmware are needed. You can of course build three and have your whole machine run on RC servos. :-) You will need an ATtiny 25/45/85 running at 8 MHz. Detailed schematics will follow when I find the time. For further information see code. Made for my DVD drive plotter, now running GRBL and accepting true gcode :-) http://youtu.be/KZ46Kgq2LHk I HEREBY CANNOT BE HELD RESPONSIBLE FOR ANY DAMAGE THIS PROGRAM/UNIT MAY CAUSE. BY DOWNLOADING YOU AGREE TO THIS TERM.