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Steppers very choppy and slow problem
« on: May 09, 2008, 11:50:26 AM »
Hello, first post, first problem.  I am working on a plasma table.  Last night tried the steppers out on the bench for the first time.  When I switch to JOG mode and activate, steppers move in the correct direction, but they are very choppy, turning at less than 10 rpm and it didn't seem to matter what settings I adjusted in the motor config screen.  Ports and pin settings are correct, breakout board LED's are lighting when they should.  My motor supplier suggested a problem with Mach 2 plasma and windows 2000.  Suggested running XP and reloading Mach.  I suspect I've missed something in the proper motor configuration. Currently set at 3200 steps/rev Any suggestions would sure help.
Re: Steppers very choppy and slow problem
« Reply #1 on: May 09, 2008, 12:26:20 PM »
Hi wlarry.

Checkout "Basic Setup of Mach3Mill"

This is found using the links at the top, Support/Documentation.

Although for Mill the motor setup would apply, it very easy to follow if after trying that you still have problems you can come back and ask

Welcome to Mach3

The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline jimpinder

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Re: Steppers very choppy and slow problem
« Reply #2 on: May 10, 2008, 03:43:19 PM »
Basically what Phil said is sound - check the support  documentation on this site.

You do no say what motors you are using, what steppers you are using or what gearing you are using on your set up. To give you an idea of mine - then you may get an idea where you have gone wrong - look in Config/Motor Tuning.

The first question is "steps per unit". This is a misleading term. It should be pulses per unit.
My motors are 1.8 degree - 200 steps per rev. My drivers are Gecko, which put out 10 microsteps per step - therefore I need 2000 pulses to turn the motors one rev. These are connected via a 3 to 1 reduction gear to my lathe main shaft  - 6000 pulses per rev.
My mainshaft needs to turn 10 times to move the saddle 1 inch. 60,000 pulses.

Therefore if your machine follows along those lines - your pulses (or steps) per unit (assuming inches) - should be well above the 3200 you are quoting.

We then get on to inches per minute movement of your saddle/table. This also is entered into the Motor tuning page (do not foget to save each axis as you complete it) If you want your axis to move at say 20 or even 40 inches per minute (remember this is fast speed - not cutting speed) - then set the speed at that and the acceleration at say 1 or 2. You may even want the table to move faster - but I would wait til you get it all connected up before you get into that.

Finally you can jog - if you use Mach 3 mill you jog at full speed, lathe - there is a percentage figure that you can change - put it up to 100% - I dont know if the plasma screens have any  adjustment.

You should find that the motors now turn in a fair representation of the speed they should move on your machine. You can fine tune them to get higher speeds out of them, and adjust the acceleration to get the best response. The number of "pulses" per unit is however, fixed, and should be calculated accurately.
Not me driving the engine - I'm better looking.
Re: Steppers very choppy and slow problem
« Reply #3 on: May 14, 2008, 11:19:46 AM »
Thanks for the help guys.  The setup was the problem.  PC wasn't giving a stable waveform... Pulses at 25 KHz would start at 30 + K then drop to 300 and 500.
Optimizing the PC with the Standard PC configuration fixed the problem.