Stepper motor voltages

The instructions for building the XCarve show the need to set the potentiometers to 2.6-2.8amps. However, there’s no mention of how or where to check these outputs. I searched through the forums but found nothing.

I think what the step is saying to to set the pot to the 2 o’clock position which should give you roughly 2.6 to 2.8 amps; no need to check it unless you’re really curious.

I’ve read a few posts that reference voltages out of spec if your carvings don’t size properly. ie. you want a .75" width object and it gives you .7" instead. I’d like to check to see where my voltages are.

To the right of each potentiometer is a metal tab labeled xref,yref,zref connect the positive test lead there and you negative test lead to the metal tab labeled “tp4 gnd”.
Then turn potentiometers while observing voltage.

Awesome. I haven’t cracked my box open yet to even look. I’ll check it tonight. Thank you!

Generally speaking, under power can cause the machine to lose steps, it will not cause the machine to shrink the size of the finished cut. If things are the wrong size and running properly it is due to needing to be calibrated to the correct steps per mm.


I’ll look that up, ‘steps per mm’.


Oh, I’ve done the calibration. I thought it was just a ‘stepper motor calibration’ and not a ‘steps per mm’ calibration; didn’t realize they were the same. I’ll check them again to make sure they’re still correct.

I don’t move the gantry by hand at all when power is on, but I do when it’s off, is that ok? Prior to powering up, I pull my gantry forward and use precision blocks to align the Y plates and then turn on my machine. It should always be square when I power it up by using this method.

if you have a DVM you can check the current.
Just have to make sure it is set on the 10A scale or you will fry the fuse.
I will post an image of what I am talking about over the weekend.

I have a voltmeter, AND…I even know how to use it. :wink: It’s this CNC thing that’s new and challenging.


It is best not to move the machine by hand. Stepper motors function pretty well as generators, so they will feed current back into the controller when turned. It’s possible for that to do damage.

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