[Resolved] Z-Axis Issues

I’m having a problem with Z-Axis motion that I hope I can explain well enough. I’m currently trying to carve some clamps (based on https://www.inventables.com/projects/work-piece-hold-down-clamps ) as my first full project, and after some time the Z-Axis starts acting oddly and it ruins the carve. After a few minutes, the sound the Z-makes changes (it becomes lower and rougher you might be able to hear it here: https://www.dropbox.com/s/3iyj3hq5zv05pt9/2015-06-23%2023.02.35.mp4?dl=0 ) and from that point on the Z- never moves up and down enough.

I saw this thread Losing Z-Axis height and it seems to say I should try adjusting the current with the potentiometer but I’m not sure if that applicable to me. If it is applicable, how would you recommend I adjust it?

Thanks for the help.

You might start with double-checking your wiring to make sure that everything going to your Z-Axis stepper motor is well connected.

If you want to adjust the dial on your shield, it’s the white square, just left of the “Z” label. It’s a very delicate dial, so don’t apply much force. Turning it clockwise will increase the voltage. You shouldn’t have to turn it very far, perhaps 45 degrees max.

I’ve seen an increase in voltage help with issues on the Y axis, which is driving two motors, but it’s less common for the Z axis, so you might investigate other possibilities first.

I agree with PeterJames on this.

I’ll double check the wiring tomorrow, but I don’t think that’s it. The machine works fine and then it freaks out and the “sound” changes… then if I cancel the carve in Easel and restart the carve it starts working again for a while, then it eventually the z-axis freaks out again after several minutes.

Do you have the acme rod or the other one? Mine did something similar when one of the tiny set screws came out. Didnt notice it until i started looking at the top of the Z axsis.

I have the non-Acme rod (the normal one). I actually did have the little pulley screws come out before so I’ve been watching that now. They seem plenty tight.

Hmm ok. I would double check your belts. ill take a picture of mine in a minute and show you how i did my belts. I havent had any slipping as of yet but im still tuning mine in.

I posted this video over the weekend, maybe it’ll help you if you think you’re having belt problems:

I’ll look at the belts.They seem tight, but it’s worth a look. It doesn’t seem loose belts would would cause it to start and stop working every time the job restarts.

Since you describe the sound changing, it could be the stepper motor current needs to be tweaked. Below are two links that will explain the process.

http://www.shapeoko.com/wiki/index.php/Tuning

http://www.shapeoko.com/forum/viewtopic.php?f=7&t=4100&p=30839

@NAM37 my bet is that the Z current pot on your gShield is actually turned up too much. When the stepper drivers on the gShield heat up too much they protect themselves by shutting down temporarily.

How hot is your shop? Is the fan blowing towards or away from the gShield?

The pot turns 270*, I usually turn it all the way counterclockwise and then just under half of its rotation back in the clockwise direction.

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The fan is pointing in the correct direction (orginally it was blowing up so I’ve already fixed that), but I’m in Florida in my garage so it is pretty hot and humid. I’ll try your adjustment. That (eventual over-heating) makes sense to me as it always starts out fine and then gets screwy after several minutes.

I have good news to report. My carve worked tonight. I think it was a heat problem. As suggested by @TaitLeswing I tweaked the voltage, and I also setup a small desk fan to keep the controller cooler. After those changes, today the sound never changed and the carve turned out fine.

Thanks everyone for the help.

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@NAM37 Great news! Go have some fun :wink: