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Author Topic: Stepper motors don't have torque in both directions.  (Read 3096 times)

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Stepper motors don't have torque in both directions.
« on: July 02, 2007, 05:12:31 PM »
I am pulling some parts off of the shelf to put together a router. I have a 12 VDC power supply, Stepperworld FET-3 stepper board, Mach 3 software and NEMA 34 stepper motors, 1.4 amp, unipolar, 8 wire.

I initially ran the steppers using K Cam just as a test (the first PC was a Win 98se machine) and the motors ran strong in both directions.

I then took this system to another system that runs Win XP Home and Mach 3 and configured it to run with this hardware. I have a really strong X-axis in both directions. My Y and my Z-axis are strong in one direction and I can hold the shaft from turning in the opposite direction.

I have checked and doubled checked the cable wiring and stepper motor driver board wiring. I have also changed the step signal to operate low with the same results.

Can you help me look for what I missed?  Thank you.
Bob P.

Offline Chaoticone

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Re: Stepper motors don't have torque in both directions.
« Reply #1 on: July 02, 2007, 05:27:45 PM »
Are all the motors tuned the same? You can see this in config, motor tuning. Each motor has a tab to access it's settings. If you change anything, push the save axis setting button for each axis. Also, check your step and direction length there as well.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Stepper motors don't have torque in both directions.
« Reply #2 on: July 02, 2007, 05:32:11 PM »
The motors are tuned to 75 for velocity and 24 for acceleration. I have used 0, 3 , and 5 for uSec step and I have not seen a difference in performance with any of the changed parameters.

Bob P.
Re: Stepper motors don't have torque in both directions.
« Reply #3 on: July 02, 2007, 05:36:23 PM »
One more detail, the stepper motors are rated for a maximum voltage of 90VDC. Is there a possibility that I am running them without enough power?

Offline Chaoticone

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Re: Stepper motors don't have torque in both directions.
« Reply #4 on: July 02, 2007, 05:49:33 PM »
Yes, that is very likely. Check out this link.

http://www.campbelldesigns.com/how-to-build-a-power-supply.php

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

vmax549

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Re: Stepper motors don't have torque in both directions.
« Reply #5 on: July 03, 2007, 09:08:50 AM »
HUM, if the power supply works ok for the X it should work for the others????? If the y/ axis run in one direction but not the other it should not be a power supply issue or neither would run ok in the opposite direction????? It sounds like a miss wired motor or bad drive. Try swapping out the good drive to one of the other axis as a test of the drives.
(;-) TP