Homing at max travel instead of zero

[pLazyN]

Hello,

I have two similar machines that use a XY cross table.
On the first one the limit switches are top and right and I configured the axis to move to positive coordinates when moving away from the limit switches and move negative for homing.
I just recently read about positive and negative coordinates with CNC machines, but the current configuration is plausible for me since the kinematics are kind of inverted on the cross table. Table moving down means tool/spindle moving up on the part.

But on the second machine the x axis is flipped. Motor and limit switch are on the left instead of right. I want to keep the logic of the axis moving right to be negative in order to use the same gcode on both machines. Therefore I changes the homing direction to +x. That homing point is not zero but max travel. therefore I cannot use the "set zero" button in ugs after homing for the x axis. I jog to the right until I hit the soft limit and zero there. After that the machine behaves as I would expect it.

Is there a way to tell ugs to set max travel instead of zero after homing? Or is this bad practice and my homing/coordinate space is messed up?

Kind regards,
Martin

[breiler]

Is there a way to tell ugs to set max travel instead of zero after homing?

The short answer is no.

Not sure if I follow the differences of your machines, but I don't think these differences should be any problem.

Make sure they both move so that the tool is relative to the material according to:

So for instance if you jog the machine in the negative X or Y-direction, the tool will move identically on both machines relative to the material.

It should not matter if homing happens in positive or negative direction. Assuming that you are using GRBL you can set the $130-$132 settings that will be applied to offset the machine position after homing. If these are configured correctly it would make the command G53 G90 G0 X0 Y0 move your machine to the absolute machine coordinate X0 Y0, and the tool position relative to the bed/material should be the same on both machines.

Note that the "set zero" is for the work position, the gcode model:s relative position to your machine.

[pLazyN]

Thanks for the explanation!
Yes, both machines move like in your picture.
Machine 1 has it´s X limit switch in negative x direction and machine 2 in positive x.

So homing and movement is correct, but after homing machine 2 sits at max travel for the x axisand I cannot click the set zero button if I want the work position the be identical to the absolute position.
Is there another way to achieve this instead of jogging to the other side and zeroing out?

[breiler]

If you want your work coordinate to be the same as the machine coordinate you can set it once and it will be retained every time you start and home your machine.

You can also create a macro or run the command and set the work coordinate offset manually through:
https://linuxcnc.org/docs/html/gcode/g-code.html#gcode:g10-l2

You can also click the work position coordinate in the DRO and set it manually:
https://github.com/winder/Universal-G-Code-Sender/wiki/Usage#digital-read-out