XXL will not home

Need help with setting up homing on our XXL

Quick rundown… Hello World worked fine, setup a test project and the laptop turned off halfway through so it stopped the project (lesson learned there!). After trying to reboot the project, found out we had never setup homing and so I went through the process of doing that.

However, it is not working… The z-axis bounces about an inch one time no matter where it is, and then the machine runs to the far right corner (where it should be going) but they do not back-off and reengage as they are supposed to and Carbide Motion does not show all values as 0.

I have changed the table dimensions to 850, I have reset GRBL to default settings, I have turned on homing in the Settings of Carbide Motion and I have run the ‘$22=1’ and ‘$h’ through MDI. I have also run homing by starting it from the Jog screen.
Followed these threads for instructions:

I am at a loss at this point and cannot find a solution so I was hoping you guys had some advice… thanks!

Have you set your table size through the MDI as well? Send $$ and see what your GRBL settings are set for $130 and $131.

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I am a newb but wanted to be sure you had correct cables to the correct port on the board. If you look close enough you will see written on the board where they need to be.

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Labeled image of the connections here:

Usually problems with homing are mis-plugged / swapped switches — yours doesn’t sound like that, since it gets past the homing operation — the not backing off the switches is odd — if the defaults actually are being retained, then I suspect that there’s some deeper problem. If the standard troubleshooting things (power down, reset PRAM and SMC if using a Mac, uninstall and reinstall the driver and attendant apps) then contact support@carbide3d.com and we’ll help you determine the difficulty.


Thanks for the suggestions, changed all recommended settings, this is what they are at now:
$0=10 (step pulse, usec)
$1=255 (step idle delay, msec)
$2=0 (step port invert mask:00000000)
$3=6 (dir port invert mask:00000110)
$4=0 (step enable invert, bool)
$5=0 (limit pins invert, bool)
$6=0 (probe pin invert, bool)
$10=255 (status report mask:11111111)
$11=0.020 (junction deviation, mm)
$12=0.010 (arc tolerance, mm)
$13=0 (report inches, bool)
$14=1 (auto start, bool)
$20=0 (soft limits, bool)
$21=0 (hard limits, bool)
$22=1 (homing cycle, bool)
$23=0 (homing dir invert mask:00000000)
$24=100.000 (homing feed, mm/min)
$25=1000.000 (homing seek, mm/min)
$26=25 (homing debounce, msec)
$27=5.000 (homing pull-off, mm)
$100=40.000 (x, step/mm)
$101=40.000 (y, step/mm)
$102=40.000 (z, step/mm)
$110=5000.000 (x max rate, mm/min)
$111=5000.000 (y max rate, mm/min)
$112=5000.000 (z max rate, mm/min)
$120=400.000 (x accel, mm/sec^2)
$121=400.000 (y accel, mm/sec^2)
$122=400.000 (z accel, mm/sec^2)
$130=850.000 (x max travel, mm)
$131=850.000 (y max travel, mm)
$132=80.000 (z max travel, mm)

Also checked switches and tried uninstalling everything and reinstalling, still no luck.

Here is a short video of what it is doing.
No matter where you start the homing operation, this is what it does.

Mine dont re engage. They home just like your video.
They hit home, then back off 5mm.
They never stop on 0,0 for home.
It’s the line
Oh yeah, and 850 was a tiny bit too wide for mine. had to go 845mm on x, i think.

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Looks normal to me, and as @jdg3 says the machine backs off 5mm from X0/Y0/Z0


I believe what we have here is a misunderstanding of terminology / workflow.

When the machine homes, it determines the machine home / origin, which as @jdg3 noted, is defined as 5mm off the switch contact for X, Y, and Z by the $27 setting

Once machine home is set, one can then manually jog to the desired origin and zero out the axes using the interface, or use one of the non-reserved (G55–59, G54 is reserved for use by Carbide Motion) work coordinate systems.

I believe this tutorial covers this: http://carbide3d.com/docs/tutorials/tool-change/

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To expand on that, one can get the desired behavior here by defining and using Work Coordinate Systems: http://www.shapeoko.com/wiki/index.php/G-Code#Using_the_Work_Coordinate_Systems

Also, there’s this article: http://docs.carbide3d.com/article/80-working-with-homing