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Author Topic: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine  (Read 13005 times)

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Offline Hood

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #10 on: December 07, 2011, 10:16:44 AM »
BTW think about it another way, 3000rpm is 50 revs per second

Hood

Offline Hood

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #11 on: December 07, 2011, 10:18:15 AM »
In any case, if that were the problem here, the motor shouldn't be spinning at all, and the servo should simply be faulting instantly, no?  I don't see how it could just spin slowly, as reported.

Regards,
Ray L.

That is why I also suggested looking at the frequency is SS config.
Hood
Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #12 on: December 07, 2011, 10:27:18 AM »
Thanks a lot for the feedback guys.

Swapping the step and direction wires or signals gives no motion.

I definitely the frequency to 256k in the SS config...this high frequency capability is the only reason i bought a SS.

The acceleration doesn't seem to effect the motor right now as i'm just running it on the bench with no inertial mass or load...but i've tried a range of values.

One other thing is that I'm sending these signals through Port 1 and into a Gecko 540 and passing the step and direction signals through the two OUTPUT channels. I believe these channels simply take a pin from the DB25 and pass through the 540. You wouldn't suspect that this is getting messed up passing through the 540 would you?
-Kyle-

Offline Hood

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #13 on: December 07, 2011, 10:31:18 AM »
Not familiar with the G540 but is that passing through optos? If so maybe they are slow and cant pass the frequency you require?

Do you have enough voltage to the motors drive to achieve the full RPM?


Hood

Offline stirling

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #14 on: December 07, 2011, 11:33:55 AM »
For a rotary axis, isn't acceleration in RPM/sec^2?  If so, 500 is not very high.
Revs per minute per sec per sec? That would be a 3rd order derivative, which would be jerk but with mixed time units - curious.

Hmmmm....  I wonder what the units are then?
Well whatever it is it has to be in terms of angular-displacement/sec^2 so revs/sec^2 or radians/sec^2 or degrees/sec^2 perhaps.

Ian

Offline Hood

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #15 on: December 07, 2011, 11:39:18 AM »
I would say it is units/sec/sec just like an axis.
As one unit of the spindle is a rev then it follows its revs/sec/sec

Hood
Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #16 on: December 07, 2011, 11:43:10 AM »
For a rotary axis, isn't acceleration in RPM/sec^2?  If so, 500 is not very high.
Revs per minute per sec per sec? That would be a 3rd order derivative, which would be jerk but with mixed time units - curious.

Hmmmm....  I wonder what the units are then?
Well whatever it is it has to be in terms of angular-displacement/sec^2 so revs/sec^2 or radians/sec^2 or degrees/sec^2 perhaps.

Ian


Yes, you're correct - Units would be revs/sec^2 or RPM/sec (which would be odd....).

Regards,
Ray L.
Regards,
Ray L.
Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #17 on: December 07, 2011, 12:39:23 PM »
my lathe has a servo on the spindle

Hey Hood,

What kind of Servo Motor/Driver are you using and how are you driving it with Mach? I'm considering returning the Leadshine motor and controller and working with something that someone else has had success with.

-Kyle-
-Kyle-

Offline Hood

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Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #18 on: December 07, 2011, 01:25:00 PM »
I use Allen Bradley drives and motors, 12.5Kw MPL-B motor on the lathe, 8kw MPL-B on the Beaver mill and 3kw F motor on the Bridgeport.
I have picked these up from eBay and you wouldnt want to buy new although quite a few of them were actually new. The price of the motor and drive that I have on the lathe would retail about £6000, I got them a lot cheaper, just over £400.

Now there is no reason that your motor and drive will not work and I suspect it may be due to you using the standard outputs on the G540 as I suspect they will be relatively low frequency outputs. I have not looked to see if there is any info on Geckos site about their max frequency though, so its just a guess.

Hood
Re: Brushless DC Servo Spindle Speed Control w/ Smooth Stepper and Leadshine
« Reply #19 on: December 07, 2011, 01:34:37 PM »
Thanks Hood,

I'm going to try and push the step and direction signals through the Port 2 on the SS and bypass the G540 all together. I've just gotta round up the right connectors and I'm good to go. There is a 5V out somewhere on the SS right that I can run to the driver to make it active Low? Right now i'm running that signal off the G540 Power supply with a resister.

-Kyle-
-Kyle-