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Author Topic: set steps per unit works but not tuning motors. they are Jerky and slip  (Read 2941 times)

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Running stable ver of mach3. c11g bob ver8.2/ gecko 203v drivers. 6515 keling pS and keling motors. Parallel port is a pci card just to make sure of one problem. Cable is new. Everything has been checked many times. Ive tried all the settings from the msg board here and nothing is working.
Read msgs about jerky/slipping motors but couldnt find anything like this.
Problem:
Motors are jerky in tuning no matter what setting or speed. 1/2 pulse 1-5 step pulse port pins etc. No enables or e-stop.. everything is off except motor specs.
There was a couple of times that in tuning, the motor actually worked and i had a chance to tweak it (vel/speed). Once i tweaked it and "saved" and I IMMEDIATLY used the arrow keys to manually move the motor again, but it went back to jerky and slipping instead of a smooth rotation.
When I went to ALT6 setting and "set steps per unit" to like 20 as an example. it remembered the setting in tuning and rotated smoothly every time, no matter what number i inputed.
PC is winxp sp2 and a clean install with nothing but internet and mach3.
I dont have any more ideas as im not an electronics expert.

Offline mr.c

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Re: set steps per unit works but not tuning motors. they are Jerky and slip
« Reply #1 on: December 08, 2009, 12:16:24 AM »
Are your motors mounted to a machine or just sitting on your workbench? Stepper motors operate as you describe when not mounted solid.
Re: set steps per unit works but not tuning motors. they are Jerky and slip
« Reply #2 on: December 08, 2009, 10:56:56 AM »
I am using a geared motor on the bench. Shouldnt it be consistent? I can understand a little variation if it isnt attached because of torque. But this is  extreme in nature to me. The motor sounds like is grating gears and then it speeds up a sec and goes back to a grating sound. But it one Mach menu it works fine. Ill hook it back up and see.
thanks.

Offline mr.c

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Re: set steps per unit works but not tuning motors. they are Jerky and slip
« Reply #3 on: December 08, 2009, 11:01:15 AM »
Stepper motors are wierd that way. Try it with the motor flange clamped in a vise or mounted solid to something.
Re: set steps per unit works but not tuning motors. they are Jerky and slip
« Reply #4 on: December 08, 2009, 01:25:58 PM »
yeah i tried that. I started checking volts etc. (got a multimeter Yeah!)
 Using the c11g BOB and mach3, i tried motor tuning and the up arrow produced +5v but the down arrow produced 1-10 MA!! No juice going in reverse. Im gonna ask Arturo (cnc4pc) about that. I may have  a lemon. I unhooked every line and Gecko from the BOB and left just the one line hooked up. What Happened the 1st time was the up arrow lit up line 5 and the down lit up line 8. I wasnt wired to line 5! I was wired to 7/8/com.
So thats where i am. Im going to check here and see who uses what for BOBs and may get a different one.
also i found a program for checking the printer pins on the c11g. SO I know my printer port is working. It lights up the EN output lights.
SO ill have to wait for an answer from Arturo or buy a different BOB. and doI really need a BOB?
« Last Edit: December 08, 2009, 09:15:29 PM by oldhack »