Z axis hitting hard past homing switch and cutting at the same depth

My Shapeoko initializes fine when I use carbide motion. Once I press the “start job” button after loading a new job, the z axis lifts up with such force and jams up without acknowledging the homing switch.
Then it starts cutting about 0.1 inch deep even when i program it to cut 0.01. I’ve adjusted the belt tension, the pulleys… I don’t know what to do.
Can anyone help?

Hi @Tee,

Chances are, the retract height you set in CC is too high (with respect to the available range of movement left on the Z axis, depending on how high you mounted your router in its mount, and the stock thickness)

Since homing works correctly in your case, the Z limit switch is working. But it so happens that the limit switches are NOT taken into account DURING a job, for a few good reasons (discussed elsewhere on this forum, basically to avoid false detections that would ruin long jobs)

If your retract height is such that the Z axis collides at the top upon retract, the Z motor is loosing step, and then while it plunges back, it goes deeper than programmed because of those lost steps, which is what you are seeing.

Are you using clamps ? Try and reduce retract height such that it clears the clamps, but not more. Try and sit your router as low as you can in its mount too. That should do the trick.

1 Like

Thanks a lot for your reply. i will try that.

Thanks. Your solution was very helpful.
The mistake I made was that my waste board was close to 1 inch and I put a 1 inch stock on top as well.
Lesson learned.


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