Trouble Homing - Grbl Error

(Mark Jurisch) #1

I’ve finally made it through my XL upgrade build, and during this homing switches were added. When I open up carbide motion, it shows homing switches setting as “true” in yellow (what does the yellow mean?), but when I try and home the machine for the first time, it then says “Grbl Error: Setting disabled”, then lands me on a screen that says homing, no where to click until I force quit the program and start over.

Gbrl v.9
CM 3.0.366 (downloaded today)

Do I need to be sending the settings directly to Grbl, even though it looks like the controller knows it has limit switches? What did I miss?

Also slightly related I am trying to set the new X limit and I’m not having a lot of luck. I’ve tried sending $130 = 850, but it doesn’t seem to register in carbide motion, so I think I’m missing something there as well.


(Scott Conant) #2

$22=1 to enable homing.

$130, $131, $132 are all useless unless you have soft limits enabled ($20=1)

GRBL documentation:

(William Adams) #3

Please see for details on that.

(Mark Jurisch) #4

Thank you, that got my into my first homing cycle, but as X moves left and should trigger, it just hits the end and tries to keep going. If I push the switch first before moving it says switch hit (shouldn’t it go to the next axis?)

Is there a way to easily check the status of the switch at any given moment?
I also saw a debounce setting, and saw 5-25 milliseconds is usually good, the S3 default is 25.

Also, where exactly should the switch be hitting on the end of the x axis? Mine currently hits on the “nut” part of the belt tensioning bracket.

Thanks again for your patience with my questions, one of these days I’ll have my machine running again :slight_smile:

(William Adams) #5

Easiest way to check a switch is to press it — there’s a light on the control board for each switch/axis which will then light up.

Ideally the switches would hit against the plates — one loses travel distance if they hit against the hardware bits — you should be able to loosen the parts in question, pull/push the switch into the desired alignment, then tighten things up. Some folks have sapped the switch to the opposite side of the plate.

(Mark Jurisch) #6

Great, I was hoping there was a way that simple to see when a switch was hit! I have a bad switch, so I’ll get that sorted out next.

(Mark Jurisch) #7

Alright, so I replaced my bum switch, but I’m still having an issue. When doing the homing, X moves toward the left (x-) but does not stop if I push the switch. I see the LED light up on the board, confirmed that it was the X switch light that was lighting up.

Any ideas? Am I still missing a setting? The settings page in CM shows homing enabled.

(Adam X) #8

Silly questions here… why is your X homing to the left? I believe the S3 homing switch for X mounts on the right side and GRBL homes “right, back, up”. Do you have an axis reversed somewhere?

(William Adams) #9

As @Adam_Xett noted, homing directions are:

  • Z up (positive)
  • X to the right (positive)
  • Y to the rear (negative)

If the machine doesn’t move in those directions, but one is sending those commands, the axis is reversed. Possibilities:

  • Z — carriage plate installed upside down (static pulley should be on the left)
  • Y — motor connectors reversed — power down and swap them
  • X — motor is mis-wired — check the connectors against the other wires and if not matching use a small tool to pop out the connectors and make them match — stepper motors may be reversed by:
    • swapping either the left or right pair of wires
    • swapping the left pair of wires with the right pair
    • reversing all four wires

If the above doesn’t address things, please let us know at and we’ll do our best to help.

(Mark Jurisch) #10

Just to close the loop on this, I figured out via pushing all of the limit switches during the homing process that my X and Z connections were switched, which explains why X was moving in the negative direction.

Also Z homes first, then X and Y move simultaneously to home. Had I known this order it would have also pointed me in the direction that I had two connections switched.

Now to get my machine squared up better now that it’s moving properly!