Homing on wall mounted machines

[349iq2345]

Hey burmy, hey Daniel @abrteguy,

@burmy

Ya, I just had to flip the whole thing 180 degrees.

This is because Stall Homing does not work against gravity.

@349iq2345

This is because when using stall homing, the controller tries to find out if the axis ceased to move, and it does this by sensing whether the stepper motor produces electro-motive force (i.e. acts as a generator), which it does only when moving. However it can sense this only during the small moment when there flows no current. But when no current flows, you have no holding torque which means the stepper runs freely, which means, it does no more hold the gantry’s weight against gravity.

You could avoid this by retrofitting limit switches (proximity sensors) instead of using stall homing. Onefinity and Buildbotics controllers support that. But the more simple solution would be to have home at the bottom thus not having stall homing done against gravity.