Motor suddenly stops

Hi there,

I've set up a basic 3-axis CNC using Arduino Due/GAUPS for a Tinyg setup.
I have 3 NEMA17 motors, 0.9deg per step, 1.7A.
I haven't done any setup to my GAUPS board, the motors are configured for full-steps. My Chinese A4988 driver chips have their current set to 0.85. I am powering this through a 24V power supply.

I am doing testing in Chillipeppr, and noticed that my Z-axis motor often suddenly halts, although it keeps on emitting the high-pitched noise for the duration that it should be spinning. It's as if an accelerating vehicle suddenly crashed into something.

My other two motors don't seem to be doing this. Any idea what could be the issue?

Thanks

Classic mid band resonance and classic gravity bias on the z axis.

Google "Stepper motor mid band resonance" for a host of ideas. Here are a few:
1. Use a higher microstepping mode on your driver. If it supports that setting... actually... just get a real driver.
2. Try /reducing/ the current on the driver (doesn't always work, but there have been cases...)
3. Add a mechanical resonance damper (e.g. a hockey puck with a hole in the middle) to the shaft.

On the gravity bias, think about this: Only one axis is fighting gravity. Only one axis is stalling. To solve the problem, apply anti-gravity technology:
1. Add a spring pulling or pushing the Z axis up.
2. Add a pulley at the top, and a line over it from the Z axis to a weight.

You could also try better lubrication (e.g. silicone or slick 50 or something like that) but I haven't had good luck with that in the past.

Sorry for the late reply, thanks for the tips James!

Glad to have been of help. I'm curious: Which of those ideas helped? And how are you liking the Duo / GAUPS / Tinyg / Chillipeppr setup?