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Motor tuning headache
« on: September 20, 2014, 04:26:53 PM »
I am trying to finish up my X2 cnc conversion and am having trouble getting my motors tuned.  I just finished three hours of futile trial and error.  I didn't want to have to ask for help, but I surrender.

I am using a kit I got off EBay from Longs Motor, with 23HS motors.  I learned after the fact that their documentation is lacking, to say the least.  I have it all set up and running, but when I try and tell Mach where to go, it doesn't want to go where I tell it.  I have tried switching the dip switches on the drivers and the config in motor tuning to no avail.

I went to the setup screen and tried calibrating that way, but the setting Mach3 gives me is over the limits.  I started at 2000 120 4 and up to 3600 steps per, but the movement never changed.  Trying to move just on inch gives me about 5/16ths and 2 inches gives me about 25/32's.

My ball screw is .2 ipr, so I figure that at 400  steps per rev, which is the lowest my motor will go, I am at about 2000 steps per unit, so it must be the acceleration that is wrong.

Can someone point me to where I can find an explanation that will help me fix it?  I searched the forum and got a gazillion hits, but have to research after every post I look at and that is too much for my current state of patience.  I just don't know what I am doing wrong here.

Thanks in advance and sorry for not seeing what is probably very obvious.

Dan

Offline 1Acnc

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Re: Motor tuning headache
« Reply #1 on: September 20, 2014, 08:41:27 PM »
"My ball screw is .2 ipr, so I figure that at 400  steps per rev, which is the lowest my motor will go, I am at about 2000 steps per unit, so it must be the acceleration that is wrong."

I am new but .2ipr to me means it needs to turn 5 time to travel an inch. If your stepper are 200 pulse per rew and you are not using any micro steps. `Mach3 need to be set to 1000. If you are using any micro step then multiply by that number also.

I put this number in steps per and then save, it have to be done for each Axis.  Open Mach3, Config, Motor tuning,  sel the axis that you want to change, place the 1000 in the bottom left square (the steps per), then Save axis settings.
Re: Motor tuning headache
« Reply #2 on: September 21, 2014, 10:40:52 AM »
Thanks 1Acnc.  I don't understand the difference, if any between steps and pulses.  My motor's lowest dip switch setting is 400 steps per rev.  It must be the equivalent of 1/2 microstepping at 200 pulses per.  I tried 800 spu in Mach3 and got no discernible difference.   I guess I could leave all the dips to off and get to 200 spu and give that a try at a 1000 in Mach.

Offline 1Acnc

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Re: Motor tuning headache
« Reply #3 on: September 21, 2014, 12:34:39 PM »
A pulses is any time a voltage goes from high to low and returns. The wave form that comes out of the computer are pulses. Step is use to define how far a stepper motor will move.  So a pulse will move the stepper motor one step if there is no micro steps set, If the micro is set to 1/8 step it would take 8 pules to move the stepper motor one complete step. If your driver is set to 400 steps and your screw is 5 rew per inch. I would set the number step/pulses in Mach to 2000. Yes, step and pulse are sometimes used as they mean the same thing. Mach3 is looking for how many pulses it needs to output the back of the computer to get the fixture to move one inch.

What I do not understand is how you changed steps and no change in distance of movement, and have no idea what to do about it.

I am going out of town and will not be able to respond for a week.
Re: Motor tuning headache
« Reply #4 on: September 21, 2014, 05:28:19 PM »
Yeah, something is screwy.  I run the steps per unit calibration under the settings tab and tell it to move 2 inches, it moves a half, but the DRO tells me it has moved 2 inches.  When I jog the axis one inch, the DRO tell me it is 4".  

It is reading one something as four somethings.  I don't know if somethings - steps, pulses, rev's. or if the fact that my gears are at 1:1 are messing with it.
« Last Edit: September 21, 2014, 05:30:46 PM by fortdick »
Re: Motor tuning headache
« Reply #5 on: September 22, 2014, 02:04:48 PM »
Okay, got it squared away.

For anyone as stupid as me, make sure you check your power dips.  I had accidently flipped off one switch that effectively increased the power to my motors by 50%.  Once I found and fixed that, the process was simple to get the motor configured in Mach.

That's 1Acnc for the explanations that helped me track down the problem.