Final cut is off by exactly 1"

Ok now this isn’t fair, I started cutting on my final piece and its not cutting according the the dimensions at all.

this is the acutal g code for the cut i’m making and the bottom pocket cut should be further down and it’s not, it’s off by 2 inches!

30 catalina dash.c2d (20.8 KB) (16.0 KB)

It started the job ok in the right spot but when moved to the second cut it’s off. now this makes no sense.

here is the cbc and gcode files. what could be going wrong now? makes no sense, its started off right!

Also forgot to mention that I heard some rubbing noises for a brief second on it’s way to cut out the second pocket. my acrylic piece is really close to the gantry, it’s just underneath it by a few thousandths on an inch.

could this be the reason why its now off?
thanks in advance for any help

I actually think that was it. I was able to start again after clamping the piece a little further down and am running the tool path again and seems to be looking good again.

lesson learned - make sure oversized workpieces clear the gantry with enough


It looks more like a “mis-measure” of the material or material position.

Yeah if it was loud enough for you to hear over the sound of the router, it probably collided hard enough to make the stepper motor lose some steps, and then everything ends up being shifted for the rest of the cut.

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Thats what I’m dealing with now unfortunately. been looking into some threads - i’ve checked the belts, set screws, and the square of the overall shapeoko , and checked the tightness of the wheels on the frame - all seem to be ok…
ive zeroed again several times but the cuts are still coming out shifted…
Did I make a big no no this time?

I had a look at your G-code and I noticed that the X span for the file is 820mm (from -410mm left of where you zeroed to +410mm right of where you zeroed):

I don’t have an XL with Z-plus to check, but it seems to me you would be pretty close (or beyond?) the X travel capacity of the XL/XXL (advertised as 32" = 813mm, but varies a bit depending on the specific setup).

Can you run an air job with this G-code and watch if you see the Z axis colliding with either the left of right rails at any point ? If so, that’s your problem.

If not, have a second look at the set screws on the X motor shaft. Sometimes it’s easy to overlook a bad setscrew alignment/tightening.

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I know I was very close but I thought I had 33" and the overall x span was just under. I did light pass on mdf before I started and it was able to do all the contour no problem and came out square.
Of course I encountered all the obstacles when I put my acual work piece…
Going over screws now…

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Any chance you centered your stock on the wasteboard slightly differently than the MDF stock you used for the test ? With so little margin, if you are off by 1inch from the machine center, you are likely to collide one side. Anyway it’s good to double-check those setscrews regardless.

I was thinking about that, it may be hair off from where the mdf sat.

Would it make more sense to orient the piece 90 degrees and start over that way? (Unless i’m wrong in thinking that gives me a couple more inches)

I noticed one of the wheels looks questionable:

So you have the XXL? As far as I know it has 33" of usable Y travel, BUT some of that is located beyond the front rail, so it may or may not be usable.

You should:

  • install your stock
  • zero as usual
  • and then jog manually along X and Y up to the limits that your G-code will be trying to reach (for your file above that was from X=-410mm to X=+410mm, and from Y=-155mm to Y=+104mm)

That way you can safely check whether the gantry will collide with the sides before running the job.

If it doesn’t, back to the setscrews. One trick is to use a marker to draw a straight line across the pulley AND shaft, run the job that has shifts in the cut, and then go back and check that line: if it’s now shifted between the part on the pulley and the part on the shaft, it’s evidence that the pulley slipped, and that something’s wrong with the setscrews.


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That damage happens when the V wheels get scuffed by the belt anchors — it’s cosmetic — you can address it by loosening the belt anchor and shifting it away from the V wheel before tightening it.


I zeroed and check my x and y axis and came in just under the limit on my x.

I went through all of the set screws and found one that wasn’t tight. Some of these set screws were hard to get the flat end of the alan wrench on so had to use the long end (with the ball end). I’m going to have to find some with a squared end as the ball end sucks at tightening especially with the long end of the alan key. I got them all as best as I could and am running the remaining g code now… it takes a long time to get to the other sections so will know in a while but seems to be ok for now… (fingers crossed)

the shaft isn’t flush with the pully on my shapeoko (see pic) so i don’t think i can use the marker method with any decent accuracy?

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Update - it is still off…
I also noticed when I stopped the job and the router was retracting to home the gantry was still making jarring noises even though it was not hitting anything…
I’m not sure how it got to be this jacked up, when I manually jog the machine around to check for jarring or skipping I don’t really encounter much but when performing a job and moving to a new location I can hear it jarring along the way…
I really hope this thing isn’t damaged, it just doesn’t operate as smoothly as it used to anymore.

Mmh. Those jarring noises should be investigated indeed.

  1. did you contact support ? If not, definitely do ( Whatever the problem ends up being they’ll take care of you and get you up and running as fast as possible.
  2. do you have a way to upload a video of a situation where this jarring sound happens ? (if you happen to have a Youtube account, posting a link in a post here is the easiest, else a link to a google drive/dropbox etc…
  3. Check your wiring for any loose connection or tension on the wiring that would only happen during specific movements of the gantry. If there are strange sounds while jogging/homing and you are sure there is no mechanical collision at those times, it could be a loose motor connection.
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Hey! The one screw holding your Y2 plate onto your extrusion is backed out a few turns. While this one screw is likely not an issue, this may be an indication of other things at play. Go through and check all your screws before continuing!

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I see it thanks! looks like some of the others have come loose good eye!

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