3.3.6 BlackBox 4X RC Servo

OpenBuilds BlackBox provides a way of using an RC servo to raise/lower a pen, in Pen Plotter type applications

NB: Advanced functionality, requires you to install a custom version of Grbl-Servo (Instructions below)

  • Grbl Settings: Send $31=255 to adjust the PWM scale to 0-255 (8 bit for Servos)
  • GCODE: Send M3 Sxxx where xxx = 0-255 Absolute Position for the servo to move to
  • You may need to add a G4 Pxxx dwell to allow the servo some time to reach the position before continuing with the GCODE


Please install our CUSTOM GRBL firmware for 2 Axes + RC Servo to enable this Functionality

  1. Download, install and run OpenBuilds CONTROL
  2. Click on Wizards and Tools in the top Menu Bar > Grbl Flashing Tool
  3. Change Machine Type to 2 Axes + Servo
  4. Configure the other settings relevant to your machine, and Flash


TIP: Remove the Relay Mode jumper to prevent the relay from clicking on/off rapidly during servo PWM operations

BlackBox version 2.6 and newer

BlackBox version 2.4 and 2.5 Only

docs/blackbox-4x/connect-rc-servo.txt Ā· Last modified: 2022/08/19 17:26 (external edit)