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Author Topic: Mach4 and my Sherline Mill , can't get the motor settings right  (Read 4059 times)

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Mach4 and my Sherline Mill , can't get the motor settings right
« on: October 30, 2015, 06:30:40 PM »
I'm using ESS and a Leadshine 3660. I think the ESS is configured properly as I can jog my X Axis  + & - but the motor is stuttering and freezing seemingly no matter how I fiddle with the Mxch 4 motor tuning settings. On the 3660 I have it set to 200 steps/Rev with an RMS current of 2.0. These are pretty standard NEMA 23 (23KM-K035-62V) steppers with a 1.8 degree step angle and a current rating of 2.0A. Anyone have a recommendation for the Mach 4 motor settings. I have a nice trapezoid at 600 counts/unit, a velocity of 100 and acceleration of 14 but the motor sounds like its about to fly apart.
Re: Mach4 and my Sherline Mill , can't get the motor settings right
« Reply #1 on: October 31, 2015, 09:43:42 AM »
I have a Denford / Sherline setup with ESS and G540. I have it set up for metric units with 1574.5 counts per unit and 559 units / min velocity and 56 units / sec^2 acceleration. My steppers are Step-Syn 2 Amp steppers. Are you sure that the steppers are wired correctly?
Re: Mach4 and my Sherline Mill , can't get the motor settings right
« Reply #2 on: October 31, 2015, 05:26:57 PM »
Not that I know anything about sherline mills... but:
Are your leadscrews metric or imperial?

If metric, seems they are 1mm pitch / revolution
If Imperial, seems they are 20t per inch

Info shown here (first few cells of top table .... stating leadscrews)
http://www.sherline.com/dimen.htm


You've set the Leadshine 3660 for full step resolution (..... so it may sound a little rough.....) common settings (generally) 8uSteps per full steps

As this would give you a resolution of:
Metric 1mm/rev / 200 / 8 = 0.00625mm / Step (or 1600 steps / mm)
Imperial 1 / 20TPI / 200 / 8 = 0.00003125" per Step (or 32000 steps / inch) [ or 1259.842519685039 steps per mm]

I'd suggest setting the Leadshine 3660 controller with the "1600" steps setting as shown on page 12/22 (OFF-OFF-ON) http://www.leadshine.com/UploadFile/Down/MX3660hm_V1.0.pdf

Stepper motor info and wiring shown here: http://www.sherline.com/stepspec2.pdf

Not that I've ever done this before... but you may wish to use metric settings if you have a metric machine and imperial if you have an imperial machine, then prefix your Gcode with G20 or G21 .... there is a bit on it here.... so that way your machine is set up correctly and if you intend to design in inches and your machine is metric it will convert your gcode units its self by doing the multiplication with little rounding errors (which you can probably see from my imperial to metric leadscrew calc above of the steps / mm)
The only catch is dont forget to put the correct prefix in the code...
http://www.cnccookbook.com/CCCNCGCodeG20G21MetricImperialUnitConversion.htm

Rob

Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: Mach4 and my Sherline Mill , can't get the motor settings right
« Reply #3 on: October 31, 2015, 05:41:24 PM »
Oh...

before I get shot down on the general statement of 8uSteps per full step...

It came from here (sort of) [4th paragraph down]: http://www.geckodrive.com/support/step-motor-basics/accuracy-and-resolution.html

Any microstep resolution beyond 10, such as 125, yields no additional accuracy, only empty resolution. By analogy, a voltmeter having a 6 digit display while having 1% accuracy would have meaningful information only in the first two digits. There are two exceptions justifying higher resolutions: The step motor is being run in a closed-loop application with a high-resolution encoder or the application requires smooth operation at very low speeds (below 5 full steps per second).

You could also use 10 u steps / full step (setting 2000 >>> ON-ON-OFF
which would be:
Metric: 2000 steps / mm
Imperial: 40 000 steps / inch (1574.803149606299 steps / mm .... same as DouglasDrew in his post above.. (almost... may have a little more inaccuracy though)).

The velocity and the acceleration really need tuning in my opinion, the acceleration is by far the more important factor given it will lead to lost steps as most of the time whilst the machine is under load it will be running at a lower velocity (feedrate) but the acceleration would remain the same....
If you are loosing steps, you may consider either lowering the acceleration, or retuning the machine to 8uStep / full step resolution ..... or increasing the supply voltage to the motors (check the drive limiting voltage!!!!! Including deceleration voltage generated or you'll kill the drive..... Toroid transformers tend to be  better than switched mode (mine sounded rough when I ran one but I was running at a faster pulse speed at full velocity though than yours would be running (not mill ... plasma).

Rob
Rob

Albert Einstein ― “If you can't explain it to a six year old, you don't understand it yourself.”
Re: Mach4 and my Sherline Mill , can't get the motor settings right
« Reply #4 on: November 01, 2015, 07:02:35 PM »
Thanks for all the additional information which now will be helpful in getting the motors tuned. But the root cause of my problem turned out to be in part what Douglas Drew suggested, a wiring problem. I was using the Sherline motor harness which has all the wire colors and lead numbers properly matched to the specification sheet that Robert Spark sent. But in the harness they had wired the black and white common A&B coil leads together. According to what I've read these both should be N/C and once I separated them the motor ran smoothly without any noise and now I can focus on step and velocity adjustments. What's weird is until now when I've switched over to ESS and the Leadshine 3660 these harnesses have been connected to the Sherline "black box" controller and in that state the motors worked fine. So how they do it is beyond me and I'm not going to root around in that controller to figure it out. Time to move on.

Thanks the the help!

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Re: Mach4 and my Sherline Mill , can't get the motor settings right
« Reply #5 on: December 05, 2015, 06:14:56 PM »
Thanks for all the additional information which now will be helpful in getting the motors tuned. But the root cause of my problem turned out to be in part what Douglas Drew suggested, a wiring problem. I was using the Sherline motor harness which has all the wire colors and lead numbers properly matched to the specification sheet that Robert Spark sent. But in the harness they had wired the black and white common A&B coil leads together. According to what I've read these both should be N/C and once I separated them the motor ran smoothly without any noise and now I can focus on step and velocity adjustments. What's weird is until now when I've switched over to ESS and the Leadshine 3660 these harnesses have been connected to the Sherline "black box" controller and in that state the motors worked fine. So how they do it is beyond me and I'm not going to root around in that controller to figure it out. Time to move on.

Thanks the the help!


They are using a unipolar driver it looks like.
http://www.globalspec.com/learnmore/motion_controls/controls_drives/stepper_motor_drives
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