GRBL alarm 8 after the first hit on X limit switch

[PropellerHat]

Hi yall!

I have tried for hours to solve this nut scratcher:

When homing Z does fine. X gets alarm 8 (failure to clear the endstop) after the first, faster search. I have them set normally closed, and $5=1.

Otherwise Z and X switches are supposed to be similar, but the homing direction is inverted for X (and Y, at the moment - will change their switches to max positions) thus $23=1.

I measured the resistance of both Z and X switches and their wiring from the RPI CNC board's endstop connectors - everything looks to be fine and similar for both: Normally the pins are grounded, 5V between gnd and endstop connector's pin when triggered.

I have no idea what might be the solution - maybe I have a dorky mistake that I just don't get by myself. Noise it most probably is not, because I have shielded cables (grounded in the PSU end) and the alarm always comes when the pull of movement is done. I tried a longer pull off (2cm off of the switch), same result.

Would pull down resistors solve this? Doesn't the RPI CNC board have pull up resistors? Can I add pull downs on top of the existing pull ups?

So weird that the Z works perfectly at the same time.

I do have A and Z limit switches connected in series because I have enabled the auto squaring homing, but I am still far from getting to wrestle with Y and A homing

Any advise appreciated!

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[hfjbuis]

failure to clear the endstop

This means that after retracting, the limit switch is still active.
Increase the retract distance (pull off distance) ($27 on grbl)

[PropellerHat]

This means that after retracting, the limit switch is still active.
Increase the retract distance (pull off distance) ($27 on grbl)

Pls read before answering. I put 20mm already, and I know what it means. What is a mystery is how to fix it.

[misterwalrus]

I know this is a 6 years old thread, but it describes exactly what is happening to my cnc today. Did you ever found the mistery?
Thank you very much,

[misterwalrus]

I just noticed that the post is not that old, 2015 was the joining date of PropellerHat. Getting old, need better glasses :-D

[misterwalrus]

Problem fixed:
Just in case somebody goes through the same issue, the solution in my case was to replace wiring of the X-limit switch with a shielded cable.
Regards