X axis crashes following belt stretch calibration

Hello,

I’m trying to dial in my shapeoko 4 XXL but am having issues calibrating my X axis. I followed threads on how to change the number of steps/MM to account for belt stretch, but anytime I send non-default values to GRBL, my gantry is able to crash into the left end (facing the machine) of the x axis while jogging to that side. I’ve tried enabling soft limits, but then my machine fails to initialize. I’ve also reduced the max travel value to 840mm but this does not appear to change anything. Any help would be appreciated.

When this happened to me, it was because I got the math wrong.

Check that the steps/mm settings used actually result in accurate movement, as opposed to even worse.

Will,

The cut I made following calibration was more accurate which leads me to believe I have the correct value. Do I need to adjust any additional values when changing the the number of steps/MM?

When calibrating did you take into account endmill runoout?

Soft limits do not work on Shapeoko machines. If during jog your can run your gantry into the rails then as @WillAdams suggested your math must be wrong. During the jog your are limited by the gbrl settings on how far your movements can go. However during executing gcode there is no limit and you can crash into the side rails if your gcode tells it to go beyond the physical limitations of your machine. So if you are setting steps per MM make sure you know the maximum movement in MM and that is the setting not your (steps per MM X Maximum setting in MM) but just the maximum MM for your particular machine. For a long time the X direction in jogging has been slightly less than maximum because the Suckit Dust boot used to be popular and the ears on that dust boot stuck out past the edge of the Z so C3D limited jogging to keep from crashing the side of the Z from crashing into the rails. So you can get a little more movement on the X just make sure you dont increase so much you can physically hit the side rails. C3D errors on the side of caution on setting maximum jogging distances.

No but I am cutting with a 1/4" bit and the slots I’m cutting are 1/4" wide. Are there any other indicators of run out that I could be missing?

This is helpful info. So I set the “X Max travel” value ($130) to 840 mm as recommended in a previous thread, but was still able to crash while jogging. Is this value only activated when running a job?

Max Travel is only headed if Soft Limits is enabled — the defaults have this set to off.

See:

I don’t run out of travel on my calibrated SO3 XL w/ HDZ, nor can I recall running out on my SO Pro w/ Z-Plus.

Does it happen for Rapid Position movements?

Nope. No issues with the rapid positions.

In that case, it’s like the old Marx routine:

Doc, it hurts when I do this.

Don’t do that.

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Aha good enough for me. Thanks for the help/suggestions.