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Author Topic: Z Axis motor skipping  (Read 6610 times)

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Z Axis motor skipping
« on: November 13, 2007, 12:02:30 AM »
I recently loaded Mach 3, the latest version but am having a few problems.The Z axis motor skips on its own, I have tried everything 2 different pcs, changing the APCI power driver to standard PC, motor tuning but nothing seems to work.I am running a 2Ghz AMD pc with 640MB DDR Ram and XP.I have a 1Ghz P3 with 256MB Ram but the Z motor still skips on its own on this pc.Both seem ok with the driver test. This problem is really frustrating me ??? as my router is almost finished but with this Z motor problem I cannot use the machine.Someone reccommended I use Turbocnc but I want the user friendliness and features  of Mach 3.Pls Help

Kind Regards
Edmond

Offline Chip

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Re: Z Axis motor skipping
« Reply #1 on: November 13, 2007, 12:56:08 AM »
Hi, Edmond

Are you saying it's lousing step's or moving without any command's ?

Is the Z problem both in up and down ?

Have you tried changing Config, Motor Tuning, "Step/Dir Pulse's" from 0 to 5 ?

Are the stepper control's all the same and set the same in Config, Port's & Pins, Motor Output's, "Dir/Step LowActives" ?

If not, Reversing an axis direction should be done in Config, Homeing & Limit's

Hope this Helps, Chip
Re: Z Axis motor skipping
« Reply #2 on: November 13, 2007, 02:52:16 AM »
Hi Chip

Yes the Z motor moves without any commands, its shaft twitches every +- 15 - 20 seconds.I have the motors sitting on my bench, first want to make sure I can solve this problem before installing them on my machine.I have played around with the Step/Dir pulse settings but to no avail.I am running a HobbyCNC 3 axis pro board with HobbyCNC 305oz/in stepper motors.I have ticked low actives on for Dir/Step, all the pins are set correctly, all the axis move when commanded its just the Z motor twitches on its on.If I disconnect the parallel port cable everything is fine so it cannot be my driver board.Thanks for the Advice

Edmond

Offline moxy

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Re: Z Axis motor skipping
« Reply #3 on: November 13, 2007, 08:27:06 AM »
Hi Edmond, Try swapping your x axis input with the z axis input(to your hobbycnc board) I f the z axis still skips then it's your hobby board otherwise it's the pc. I suspect that the optoisolator for the z axis might be marginal and is triggering randomly.
Regards
Les

Offline GaryB

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Re: Z Axis motor skipping
« Reply #4 on: November 13, 2007, 08:47:31 AM »
Edmond, I suspect you have noise. Check all your connections and install direct grounding.
Went through that after moving the machine some time back, lost the ground connection on the dust hose, everytime we turned the dust collector on the router would happily travel down the x-axis one click at a time.......on its own.
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Re: Z Axis motor skipping
« Reply #5 on: November 13, 2007, 09:54:35 AM »
Hi Gary B and Les

I will try your suggestions today when I get home from work.By the way the board is not optoisolated from the pc, could it be the parallel port cable or something similar, if I had to optoisolate the pc could someone recommend a circuit or board.A lot of people use the HobbyCNC board with no problems despite it having no optoisolation.I have swapped the stepper motors but not the inputs yet.

Thanks
Edmond
Re: Z Axis motor skipping
« Reply #6 on: November 15, 2007, 12:15:25 AM »
I have tried all the suggestions you guys mentioned but the motor still skips on its own, so it must be the pc.I have tried TurboCNC yesterday and the motors work perfectly in it but I dont like a DOS based program its not very user friendly.If I got a parallel port card would that solve any problems? Do you guys have any other suggestions as I really want to use Mach 3 for my machine.

Kind Regards
Edmond

Offline Chip

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Re: Z Axis motor skipping
« Reply #7 on: November 15, 2007, 01:17:23 AM »
Hi, Edmond

Post your Mach3Mill.xml file, It's in your c:\Mach3 folder, Use the Reply Button lower right to Attach it, You'll need to make a copy of it and rename the copy

to EdmondMach3

Dose your Z Axis just move in one direction on it's own ?

Thanks, Chip 
Re: Z Axis motor skipping
« Reply #8 on: November 15, 2007, 06:10:27 AM »
Hi Chip

I will post the file tomorrow.The Z motor just twitches its shaft sometimes in one direction then the other.

Regards
Edmond
Re: Z Axis motor skipping
« Reply #9 on: November 15, 2007, 11:58:44 PM »
Hi Chip

I could not find the xml files, I could only find the xmlbackups folder I hope its the right one.I checked the motors again and noticed the Z motor steps only in 1 direction by itself.

Regards
Edmond