Z axis gone too far


Today, two or three times, by mistake my z axis went too far down into the material while I was setting the home position for my carve. To my horror, it resulted in it going all the way up and then, crushing the limit switch, continuing to try to go up with the motor forcing. Then it went all the way down and forced again. This happened a couple of time and there was nothing I can do for like 10 seconds each time it was trying to go off limit. I am wondering what’s the damage to my machine? what pieces shoud I be worried about? I’m sad because I just bought this :frowning:

Welcome to the club. Last time I did it, I bought another switch and about 4 spares…

When this happens, hit the power switch on your power supply - your computer may keep sending commands, but the X Carve will at least stop reasonably quickly (invest in an emergency stop switch).

Running upwards, I’ve killed a couple of switches but have caused no damage (acme rods & delrin nut all OK). I’ve previously crashed the tool into the work sufficiently hard that I broke the collet off the spindle (the 24V original version), destroyed the mount for the eccentric nut and pulled off one of the V Wheels.

After replacing the eccentric nut & spacer, adding some locknuts and upgrading to the DeWalt router, everything has been fine. The moral of the story - the machine itself appears to be surprisingly robust.

With the power to the stepper motors on (so they’re held stationary) and the power to the spindle off (so you can’t lose a finger), grab the spindle and try and try and move it in each direction. Check whether you’ve got any movement anywhere and try and note what’s causing it. If fixing it isn’t immediately obvious, post a question here.

Carefully run the Z axis up & down over most of its travel (avoiding the sudden stops each end). Does it run smoothly? Are there any hints indications the stepper motor load is changing (listen to the noise it makes, make sure speed appears consistent)?

I’m guessing it’ll probably be Ok.

The most common causes for me doing this are:

  • Thinking UGS is set for mm when it’s set for inches and hitting the Jog arrow half a dozen times
  • Forgetting to re-set or zero one of the axis (typically Z) after a tool change or material change
  • Having a drink, while I’m playing

Your mileage may vary of course…

There probably isn’t any damage besides the limit switch. They are $2.50 to replace. But…

Inspect everything for physical damage, bending, etc. Check the tightness of all the fasteners, check the V wheels, check the belts. Check the bit and collet if that was pressed into any material. Also check the squareness of the Z axis again and make sure those fasteners are tight. Something similar happened to me using UGS, and everything was fine except for the bit (which snapped) and the Z axis was slightly out-of-square.

Consider investing in an Emergency Stop switch. This will allow you to halt everything if something goes wrong again. In the meantime, if you run in to trouble like that, turn off the power switch on the power supply as quickly as you can get to it. This will not harm the machine. Be sure to exit the program or kill the job in the software before switching it back on.

Here’s the answer to stoping this
(2 instock) Ultimate X-carve Limit Switch Shield

I had that happen today for the first time, and it was the first time I got to hit the “Oh Shit” button. Worked great! I manually lifted it out of the material, and stopped it on Easel as soon as I reset the big red button.

If your z axis limit switch only has its metal arm come off, and if that metal arm still has its two small nubs that the arm hinges on, you can just snap the arm back into the the socket on the switch body. Been there, done that. For more info on E-stops, search the forum.


Thanks a lot for you responses, after the incident I am much (much) more careful when setting my home position. I figured out that what happened is when I was changing my value from let’s say 1 inch to 0.1 inch and going right to clicking the arrow it didn’t take the change into consideration. I have to click elsewhere and make sure that the new value is set. I now always move it UP first so I can see the change is effective.

I tightened up a bit the wheels and everything seems to be fine, I had successful carving yesterday and I was pretty happy. The only small problem I have left is sometime the second pass is slightly off but I am realizing now it might very well be that my X axis belt has a little less tension than it should.

Thanks again :smile:


Unless… :grin:

Yes Alan, if you accidentally run over your X-Carve limit switches, you may need to replace them. :fearful:

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Looks like isn’t it. Run over with car. I found it somewhere on this forum.