That’s different. If you have access to an oscilloscope then it should be an easy exercise. It would be even better if the oscilloscope had a transient trigger mode.
I have been having trouble with the limit switches recently too. I didn’t have any for the first few months, who knows what’s going on.
I’ve wasted a few carves and I wasn’t too sure how to handle it when it occurred to me that I don’t really need the limit switches to work as actual limit switches, I only use them for homing.
So I just turned off hard limits.
This way I have a repeatable homing position but I don’t have to worry about the limit switches (and wiring) causing the machine to stop.
Yes, definitely!
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Hello, I am having trouble with my Z-axis limit. I haven’t been able to get my z axis limit switch to work, but all the other limits work. I am using an CNC arduino shield, version 0.9. Following your instructions i can monitor the limit switch states, and I cannot get the z limit to trigger, even after disconnecting everything and simply bridging a wire between the z limit pins. Any ideas why my z limit dosnt work?
p.s. I have tried multiple arduino boards, on all of them I have found pin 11 to be in a low state via a digital probe
Any help is appreciated
If you are using grbl version 0.9 then the Z axis homing switch connection is D12 and D11 is the PWM connection.
If you are using grbl version 0.8 then D11 is the Z axis homing switch connection.
Thank you so much I completely missed that
still error with your homing switch? try to change homing pull-off to go little far from your limit switch… i change my homing pull of to 5mm from switch ($27=5)… and done, it works…!!!
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Hi Phil. I’ve been reading through this long thread. I think I might have some homing switch issues myself. I frequently get a homing fail. I’ve done a few things to track down the issue as suggested here, but I don’t think I’ve completely cleared it up. It’s usually my X-axis that stops first, so I’m putting a new switch on it. I wonder if I don’t have some of the “ghostly” issues it seemed like you were having. I am running LarryM’s Grbl 1.0c. Settings below. But, what I would really like to know is how you fixed up your machine to work and how you do the “normally closed” limit switch setup. I think that might solve my problem as well.
Grbl 1.0c [’$’ for help]
modified by Larry Mayberry
[’$H’|’$X’ to unlock]
$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=3 (dir port invert mask:00000011)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=19 (status report mask:00010011)
$11=0.020 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=1 (soft limits, bool)
$21=0 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=3 (homing dir invert mask:00000011)
$24=750.000 (homing feed, mm/min)
$25=750.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$30=12000. (rpm max)
$31=0. (rpm min)
$32=0 (laser mode, bool)
$100=40.000 (x, step/mm)
$101=40.000 (y, step/mm)
$102=188.947 (z, step/mm)
$110=8000.000 (x max rate, mm/min)
$111=8000.000 (y max rate, mm/min)
$112=500.000 (z max rate, mm/min)
$120=500.000 (x accel, mm/sec^2)
$121=500.000 (y accel, mm/sec^2)
$122=50.000 (z accel, mm/sec^2)
$130=781.000 (x max travel, mm)
$131=785.000 (y max travel, mm)
$132=85.000 (z max travel, mm)
Well, I rewired my homing switches so they all have shielded wires. My switches were also different from each other; they were from different stores and different specs. (Could that cause issues?) I did a little rewiring of at the gshield, arduino and power supply as well. For now I left it normally closed. I wanted to make incremental changes to see what solves the problem. So far, it looks like shielded wires did the trick.
It sucks attaching those limit switches and rerouting wires.