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Author Topic: HELP!!! stepper motor running rough in one direction only  (Read 1439 times)

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HELP!!! stepper motor running rough in one direction only
« on: September 15, 2021, 02:11:37 PM »
Hi,
At the very end of my teether.
I'm running mach3 using a gecko g251x board. Just the stepper motor is hooked up (it is free turning in both directions). In one direction, it runs smoothly and perfectly. In the other direction, it loses steps and vibrates but still turns. I've tried change every setting in Mach3 to no effect. Number of steps, velocity, acceleration, pulse width, basically everything checked. The driver test says the computer is good.
Any ideas hugely gratefully received. I've got paid projects mounting up with a direct correlation with stress levels.
Thanks.

Offline Tweakie.CNC

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Re: HELP!!! stepper motor running rough in one direction only
« Reply #1 on: September 16, 2021, 12:51:34 AM »
Have you tried changing (and applying) the Step Low Active state for the axis in Config / Ports & Pins / Motor Outputs  ?

Tweakie.
PEACE
Re: HELP!!! stepper motor running rough in one direction only
« Reply #2 on: September 16, 2021, 02:38:28 AM »
Yes. Applying step low state leads to continuous spinning in one direction and nothing in the other direction. Does that hold clues?

Offline Tweakie.CNC

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Re: HELP!!! stepper motor running rough in one direction only
« Reply #3 on: September 16, 2021, 02:42:55 AM »
Perhaps try replacing the stepper motor and/or check that the phase connections are correct (A,+A / B,+B) - check with multimeter rather than rely on wire colours.

Tweakie.
PEACE
Re: HELP!!! stepper motor running rough in one direction only
« Reply #4 on: September 20, 2021, 05:11:02 AM »
Hi,
Checked wiring and replaced stepper motor.
In one direction, approx. half the steps are lost.
Exactly the same behaviour persists with both smoothstepper ESS and direct-to-computer parallel port lead. I have grounded both at the point where the dir and step are led into the g251x module. No long leads anywhere.
Any further suggestions really appreciated!

Offline Tweakie.CNC

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Re: HELP!!! stepper motor running rough in one direction only
« Reply #5 on: September 20, 2021, 05:18:35 AM »
Not good news but as you have thoroughly checked everything else, all that remains is a fault with your gecko g251x

Tweakie.
PEACE
Re: HELP!!! stepper motor running rough in one direction only
« Reply #6 on: September 20, 2021, 05:48:43 AM »
I've replaced the g251x with same results!

Offline Tweakie.CNC

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Re: HELP!!! stepper motor running rough in one direction only
« Reply #7 on: September 20, 2021, 05:57:49 AM »
just a thought, you do have the stepper motor bolted down rigid and not just sitting loose on the bench ?

Tweakie.
PEACE
Re: HELP!!! stepper motor running rough in one direction only
« Reply #8 on: September 20, 2021, 06:22:30 AM »
Hi tweekie,
Thanks so much for your input.
I've did have it loose, but same behaviour bolted down.
Re: HELP!!! stepper motor running rough in one direction only
« Reply #9 on: September 20, 2021, 06:25:39 AM »
Are there any MACH3 settings I'm missing?
The g251x should work ... it is powered up and delivering 2A which is the rating of the stepping motor.
Can I record somehow the step pulses coming out of my computer to see if MACH is outputting the same number of steps for each direction? I don't have an oscilloscope, nor will I buy one.