Machine making random turns

My machine is seemingly ignoring toolpaths and randomly moves around. I have previously successfully run the same file on the same material, feeds, tool, etc. This is so odd it can only be explained in picture.

The only thing I can think of is possibly static?
It seemed to run into a problem near the top left, went wild and cut through the tabs, possibly made the tabs to thin and depth of cut too deep. Then on the right It continued the path half an inch to high on the y-axis, and then made a rectangle cutting directly through the part. That’s when I noticed and stopped it.

If the same file has been successful previously, have you looked into the physical movement of your Shapeoko? Are the belts tight, V-Wheels in good condition, etc?


Are you using Carbide Motion to drive the machine? What is the version you are on now, and what was the version you ran this file on last time, if different?

Looks like lost steps. Check the machine mechanically, belt tension, pulley set screws, eccentric nuts, &c.

I’ve found cutting is more reliable if you avoid slotting — add geometry and cut as pockets down to at least the tab depth.


Looks like that might have caused that result. ( I notice that the upper tabs are missing from Both cut items)
Cut too deep and lost the upper tabs, cut material started to chatter and choked up the bit,(correct area for this to happen, given the spindle position and direction of rotation) piece of material broke and knocked the spindle out of position…?
…that is, if I were to guess at it…

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This is a major problem that I am still having. I have tried updating my software, grounding my machine, a huge range of feeds and speeds, different tools, belt tension, HDZ, everything.

I can run the same toolpath for a few days with no issues, and then for seemingly no reason the software just decides to cut a toolpath waaay to deep, or to the side.

Today halfway through a run it decided to cut a certain path much deeper than unusal, so I restarted it, same thing. Checked, and it still had the right Z zero.

I have no idea what is causing this and it has cost me hundreds in lost material.

Shoot, I’m embarrassed, I checked my carbide create file and the depth of that path was set 0.1 inches deeper than I had it before. Still, I know I didn’t change that, so I don’t really know how it happened.