Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: gently101 on September 15, 2021, 02:11:37 PM
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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.
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Have you tried changing (and applying) the Step Low Active state for the axis in Config / Ports & Pins / Motor Outputs ?
Tweakie.
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Yes. Applying step low state leads to continuous spinning in one direction and nothing in the other direction. Does that hold clues?
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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.
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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!
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Not good news but as you have thoroughly checked everything else, all that remains is a fault with your gecko g251x
Tweakie.
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I've replaced the g251x with same results!
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just a thought, you do have the stepper motor bolted down rigid and not just sitting loose on the bench ?
Tweakie.
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Hi tweekie,
Thanks so much for your input.
I've did have it loose, but same behaviour bolted down.
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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.
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Or the pulses coming out of the g251x board?
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I don’t think that checking the pulses will be of any help to you. Mach3 will output exactly the same number of pulses and type / quality of pulses for a +100mm move as it will for a -100mm move the only thing that changes is the active state (logic) of the Direction signal.
If Mach3 drives a stepper in one direction then (within the limits of my knowledge) it will drive it in the other direction unless…
The motor is incorrectly wired or otherwise bad.
The stepper driver is bad.
Mach3 has the step pulse width set incorrectly and or the Step Low Active state set incorrectly (both of these settings are to match the requirements of the stepper driver).
The Mach3 Motor Tuning Velocity and Acceleration settings are set far too high.
If Mach3 had a corrupt installation or other factors were set incorrectly then the stepper motor would not turn correctly in the one direction.
Tweakie.
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Quick update.
I bought a new motor driver CW5045 to try. It runs perfectly at less than half the price of a g250x. Problem solved but I still don't know why the 2 new gecko modules were not working. My advice is to avoid the pain, stress and tears and get something else.
Thanks so much Tweakie.CNC.
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I am pleased that you found the issue and have it sorted ;)
Tweakie.