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Author Topic: Stepper Motors moving with no input.  (Read 4405 times)

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Stepper Motors moving with no input.
« on: February 04, 2010, 11:22:32 AM »
I have been using my home made cnc for about 2 years now. Everything was working fine.....BUT now for the last week or so I have been having erratic movingment from my X and Y axis. The Z and A are fine. The stepper motors (X and Y) will start moving even when there is no button pushed in Mach 3. This only seems to happen when my cnc is turned on. At first I thought it was a feed back loop from the cnc or maybe I needed to ground the table and cnc. I have tryed shieding the wires to the X and Y motors with no luck.

So at this point I have no clue as to why X and Y would move without output from Mach 3.

Both X and Y are Grounded.
Both the cnc and Table are grounded.
Both X and Y wires are shieded by non conductive tape and a plastic anti static wrap.
Both the X and Y are Anaheim Automation nema 34 motors with 1200oz/in.

Thank you in advance.
Roger McC.

Offline stirling

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Re: Stepper Motors moving with no input.
« Reply #1 on: February 04, 2010, 12:00:39 PM »
does this happen when your controler is on but your PC is off?

Ian
Re: Stepper Motors moving with no input.
« Reply #2 on: February 04, 2010, 12:27:11 PM »
NO
The computer is on and Mach 3 is running... When I turn on my cnc I get stepps with my X and Y axis. No other program is running, I am not connected to the internet or any other computer. I am not connected to a printer. It is not a ground issue, both the cnc and table are grounded and the controller and Bread Board. The humitity in the room is set and mantained at 45. The Tempature in the room is 20 degrees C or like 80 degrees F. I have a fan attached to each stepper motor that pushes 60 CMF's of air...I think this should be enough.

Thanks again in advance.
Roger McC.

Offline Hood

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Re: Stepper Motors moving with no input.
« Reply #3 on: February 04, 2010, 01:43:24 PM »
If you switch on the controller without Mach does it happen?
Hood
Re: Stepper Motors moving with no input.
« Reply #4 on: February 05, 2010, 09:52:10 AM »
Hi Hood
The answer is NO
The skipping with only happen the moment I turn on my cnc. I have grounded the table thinking it might be that, I have changed to wires thinking one might be frayed, I have even moved the control panel off the table and onto a sheet of Rubber  on the table next to the cnc.

Offline Hood

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Re: Stepper Motors moving with no input.
« Reply #5 on: February 05, 2010, 10:00:44 AM »
Does it happen if the Reset is flashing or is it only after you have pressed Reset?
Hood

Offline mr.c

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« Reply #6 on: February 05, 2010, 12:22:16 PM »
When you state "turn on my cnc", are you referring to powering up the drives?
« Last Edit: February 05, 2010, 12:31:46 PM by mr.c »
Re: Stepper Motors moving with no input.
« Reply #7 on: February 05, 2010, 12:55:07 PM »
OK the drives or turned on, the controler is turned on, the reset is not flashing. The cnc milling machine has caused a skipping feature to occur only in the X and Y axis but not the Z axis.
The X and Y axis will jump a few steps in a random direction. I move the X axis +2 and Y +2 I might end up at x1.5 and y 2.3 then it might move to X -1 y2.1.

I can turn Mach 3 on and turn the drives on and neither X nor Y will not move but when I turn on the cnc machine and X and Y start moving randomly on their own. When I say on thier own I mean I have not pressed any button or touched the mouse.

Offline zarzul

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Re: Stepper Motors moving with no input.
« Reply #8 on: February 05, 2010, 01:03:40 PM »
Noise most likely.  Where from is the question along with why now and not before.

How is your wiring, are all your signal lines shielded and grounded (one end only).
Do you have any VFD's ?
Re: Stepper Motors moving with no input.
« Reply #9 on: February 05, 2010, 02:04:35 PM »
Does your spindle motor have brushes? If they are worn they start arcing and produce high RF noise.

Someone else on the forum way back had a similar problem.