Homing on wall mounted machines

[burmy]

So I’ve wall mounted my woodworker and upped to drive current to 3.6 in an effort to get the x axis to move up correctly. My machine homes to the right for some reason so I assumed that stall homing was not set correctly so I upped the stall homing current to 1.6. Idle current is also set to 1.6. Still no help. Every time I home it hits the high y rail and then loses it and falls back down to the bottom rail. It seems to do this no matter where I set the drive current or the idle current. Yes, I am beginning homing several inches away from the ends of travel area to engage homing sequence correctly. Anyone going wall mounted fighting gravity like me?

[burmy]

Ya, I just had to flip the whole thing 180 degrees. Support was pretty good about helping through email.

[Aiph5u (Aiph5u (not affiliated with Onefinity))]

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.

@Aiph5u

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.

[burmy]

Ya, I home at the bottom.