FIXED: Crash while homing Z-axis

Hi. I’m having trouble on my initial attempt running through the “Setup your machine” routine. The wiring test / motor jog works fine. Spindle control works fine. The “Limit Switch Setup” is a problem-- the Z-axis crashes, wont stop with the limit switch.

I’ve tested the limit switches on all axis with a multimeter, the wiring and functionality is just fine. With the power off, each switch closes as it should. I’ve checked the order of the wiring on the header and from left to right it’s:

X limit switch connected to pin D8
Y limit switch connected to pin D9
Z limit switch connected to pin D10

I’ve even gone so far as to jog the Z-axis in “Wiring test/motor jog” to look for the switch to trip with a multimeter. It does.

I brought up the Arduino IDE and used the serial monitor to query grbl and I’ve posted that output below.

I’d appreciate any suggestions as to where to go from here, or what other troubleshooting I can try. Pretty frustrated.


Grbl 0.9i [’$’ for help]
[’$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=3 (status report mask:00000011)
$11=0.050 (junction deviation, mm)
$12=0.002 (arc tolerance, mm)
$13=0 (report inches, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=3 (homing dir invert mask:00000011)
$24=25.000 (homing feed, mm/min)
$25=750.000 (homing seek, mm/min)
$26=250 (homing debounce, msec)
$27=1.000 (homing pull-off, mm)
$100=40.000 (x, step/mm)
$101=40.000 (y, step/mm)
$102=188.976 (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=790.000 (x max travel, mm)
$131=790.000 (y max travel, mm)
$132=100.000 (z max travel, mm)

Many thanks,


Is that crashing while doing HOME or crashing when you’re jogging it manually.??

You values are perfectly correct. Those switches are for Homing purpose. They’re not limit switch. One time use only before start a new job. It doesn’t stop either one Z,Y or X while you’re running the machine.
There is Soft Limits and Hard limits setting described in this forum if you search how to do it. Other than that also there is instruction how to setup Limit switches for both sides of X and Y as well as Z axis. That is totally different wiring and hardware configuration.

It’s crashing during homing. When I say “crash” what I mean is that the z-spindle moves up and doesn’t stop when encountering the homing switch.

I’m fine with these switches used as homing switches… I just want them to work.


I had the header wired incorrectly. Once I set the “re-read the instructions” bit to 1, my problem cleared right up.

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You better go over your connections and switch pins one more time.
Now you posted as an resolved. Good. Happy carving. Welcome to community Jason.

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Thank you, Alan! Much appreciated!

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I am having the same problem… But i don’t understand what you did to fix it. Could you explain the steps a a bit more?


Yes please,I would also like to know how you done it

i dont understand what u are saying fixed ur problem mine is doing the same. what bit to 1 are you referring to

I think this was an inside binary joke. In binary 1=yes and 0=no.
.in layman’s terms he reread the instructions.

I believe he moved the wire from NC to NO on the limit switch or something else that was clearly explained in the instructions that he had simply not done per the instructions…

What issue are you having though? Its going up, hiting the limit switch and not stopping?
If so, you can go to machine>general settings>machine inspector and see the lights from triggering the switches, then press each of them by hand and identify if they are wired properly and then adjust the wiring to make them work when manually pressed & the problem will be fixed

I did that n I had to print instructions I put this together by myself months ago n everything worked fine but my laptop was slow n driving me insane so I bout new one that is faster n trying to get it set up with it n that’s what it does it goes all the way up n doesn’t stop. It already broke the homing switch once n I replaced. I have checked wires their was some loose n fixed n when I check the lights on the switches like u said on machine check the homing switch light comes on so I’m so frustrated. It works without homing it but everytime I think I’m getting the hang of the machine it messes something up.