Home After Program Vs Initialize

Machine Initializes to X, Y (-0.118, -0.118) but… 90% of the time after a program runs, it returns home and shows a machine position of X, Y (-0.197, -0.197)? So of course I close the program and then initialize it again to the -.118.

Any Thoughts on how to fix this? Should the machine position ready -118? my thought is that it should read 0? no?

Pretty new here and appreciate how nice everyone has been!

Hi @erikste,

0.197" is 5mm, and 0.118" is 3mm.
3mm is the homing pull-off distance that’s configured in GRBL (param $27) when sending the machine configuration from carbide motion. So each time the machine homing is executed, it should end up at -3mm, -3mm so (-0.118, -0.118) as you see. It’s not (0,0) precisely because of this “pull-off distance” that GRBL enforces after homing, such that the machine is not exactly at the position where the switches triggered (for proximity switches like we have now, it does not matter much, but Shapeokos used to have mechanical limit switches, and keeping them pushed would not be great)

What happens at the end of a program is a return to “home” position, and it so happens that the pull-off distance used to be 5mm in the past, so I wonder if CM’s behavior to make the machine return to home position after a job is not a hardcoded (and now obsolete) move to absolute (-5mm, -5mm).

Anyway, what matters is that the machine does not lose its mechanical reference, so if you manually jog back to your zeroes after the automatic move to (-0.197, -0.197) after a job, and you are still spot on on your set zeroes, then it’s all good and no need to worry about where precisely the machine returns.


Why thank you much. I am kicking myself because I thought that it might be irrelevant and didn’t think to just do a reference hole to test. GRR. :slight_smile:

Still strange that it is sometimes 3 and sometimes 5mm. I can’t think of what I would be doing differently in the cam setup for fusion 360.

Thank you!

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It’s probably nothing you do in Fusion, I’m still surprised that it would vary from one job to the next though. If you can upload a gcode example that moves back to -3mm, and another one that moves to -5mm, we could double-check that. For science :slight_smile:

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There is a finite number of steps, and the machine can only move along the grid created by them.

After homing it should pull off by the pull off distance — if the home position isn’t set to be that distance, then one can get this sort of discrepancy.

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