Bit Change - Moved X Axis Fail

So I’m just kinda learning still. I did up a fairly basic design that was separated
into 2 toolspath files to allow for a bit change.

When I tightened down the bit the router/toolhead shifted on me. I continued the
job knowing it would be “off”.

So question for y’all. How do I lock down the motors to help prevent this shifting?
I know on a 3D printer when doing a filament change the motors will stay powered
on to prevent movement. Is this possible to do with UGS?

I’ll definitely go easier on my bit change firmness.

Any help is appreciated.


Hey Kris
What I do is re-zero between any tool changes - roughing/finishing, bit profile etc. This will get rid of any accidental shift of the machine and any difference in bit length or insertion depth. Square/rectangular pieces are fairly straight forward if you aren’t working right out to the edges and it can be a pain if you’re working with round pieces. If I’m going to lose my zero reference point with the first tool path, I’ll make a virtual zero point that I can always reference.

Kris, Did you power off the controller while you changed the bit? If you left it on the steppers should be held in place, just like your 3d printer. I’ve changed many bits without issue. The only re-zeroing I do after a tool change is for the z height.

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Nope, left controller on. I loaded my next toolpath file. Would the steppers be active if just sitting idle? Doesn’t feel like the motors are on and locked though?..

Maybe I don’t know my own strength for tightening down the bit?

I just want to re-zero Z and continue on.

I’ll keep playing with it.

Appreciate everyone’s input.

I think you’d be looking for the $1 = 255 command which keeps the steppers on hold as long as the machine is powered, you can read about it here:


Perfect. I think I’ll make a macro key for thi s. Lock/unlock.


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@chrismakesstuff Chris: I don’t seem to be having any issues, but this is good to know as the machine wears in. Is there any downside to using this? Does this shorten the lifespan of the motors?

It can have a slight effect on their lifespan, yes. If they’re constantly ‘on’ then they will become quite warm in the locked position