Machine stuck against the front sensors

 cnc-milling, pro, usage

1. Description of the problem

When performing a "Homing" the machine comes towards you but gets stuck when touching the sensors. 

It declares an emergency stop and doesn't want to move backwards anymore. 

2. Possible origins

This happens when the gantry is perfectly square to the frame, for example if you use the "Gantry Square" procedure and home the machine afterwards. 

3. Solution

  1. Go to the machine coordinates tab.
    1. Double click on the Y value.
      1. Enter 50 en press "enter".
        1. Using the arrows, send the machine a little bit backwards.
          1. Close PlanetCNC, shutdown the Raspberry and switch off the power.
            1. Manually turn the right ball screw to "twist" the gantry (90° is enough).
              1. Switch the machine back on.
                1. Home the machine.
                  1. Square the gantry.

                    To avoid this from happening again, we'd recommend to only 'home" and "square" when needed (ex: only when starting up the machine, not at every milling session).