Stepper vs. Servo Question for Turning Center
06 Jun 2013 07:09 #35310
by Zahnrad Kopf
I see! Well, I'm completely open to change, here. Yes, the steppers were 200 steps per rev, but if the result is BETTER resolution at some other PPR count, I'm open to it. They are not directly coupled at the moment, rather they are driven with belts and pulleys. And... buying pulleys is easy if a change is needed. But if push came to shove I can hob, WEDM, or mill anything I want for tooth counts or form.
Replied by Zahnrad Kopf on topic Stepper vs. Servo Question for Turning Center
The more the better, really. You won't be running the motors at 4000rpm, I wouldn't have thought.
The Mesa card can count encoders at Mhz.
Presumably the original steppers were 200 steps per rev, so you need some multiple of that to achieve the same resolution. (assuming direct coupling?)
I see! Well, I'm completely open to change, here. Yes, the steppers were 200 steps per rev, but if the result is BETTER resolution at some other PPR count, I'm open to it. They are not directly coupled at the moment, rather they are driven with belts and pulleys. And... buying pulleys is easy if a change is needed. But if push came to shove I can hob, WEDM, or mill anything I want for tooth counts or form.
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06 Jun 2013 07:12 - 06 Jun 2013 07:12 #35311
by Zahnrad Kopf
It isn't, yet... I was planning on grabbing a 3HP 3Ø motor next week and coupling it with a VFD. But if there's a better idea I am all ears.
Replied by Zahnrad Kopf on topic Stepper vs. Servo Question for Turning Center
Threading definitely. Indexing is dependent on the motor more than the controller. What type of motor is it?
It isn't, yet... I was planning on grabbing a 3HP 3Ø motor next week and coupling it with a VFD. But if there's a better idea I am all ears.
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06 Jun 2013 18:01 #35323
by BigJohnT
Something doesn't look right with a 3hp spindle motor and nema 23 steppers for the axes. What was the original spindle motor size?
JT
Replied by BigJohnT on topic Stepper vs. Servo Question for Turning Center
Threading definitely. Indexing is dependent on the motor more than the controller. What type of motor is it?
It isn't, yet... I was planning on grabbing a 3HP 3Ø motor next week and coupling it with a VFD. But if there's a better idea I am all ears.
Something doesn't look right with a 3hp spindle motor and nema 23 steppers for the axes. What was the original spindle motor size?
JT
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06 Jun 2013 18:15 #35327
by andypugh
You want at least 1000ppr *(4000cpr) encoders, I would think.
Replied by andypugh on topic Stepper vs. Servo Question for Turning Center
You might want to consider increasing the gear ratio. Steppers tend to max out at a few hundred rpm, whereas servos can do a few thousand. But try it first with the original gearing, see how it works out.I see! Well, I'm completely open to change, here. Yes, the steppers were 200 steps per rev, but if the result is BETTER resolution at some other PPR count, I'm open to it. They are not directly coupled at the moment, rather they are driven with belts and pulleys. And... buying pulleys is easy if a change is needed. But if push came to shove I can hob, WEDM, or mill anything I want for tooth counts or form.
You want at least 1000ppr *(4000cpr) encoders, I would think.
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06 Jun 2013 18:21 #35329
by Zahnrad Kopf
John,
It is a 5HP 380VDC motor. Emco REALLY over built these. I figured I could get away with a 3HP motor since the machine is so compact. I have ZERO issue with going with a 5HP motor though.
Replied by Zahnrad Kopf on topic Stepper vs. Servo Question for Turning Center
Something doesn't look right with a 3hp spindle motor and nema 23 steppers for the axes. What was the original spindle motor size? JT
John,
It is a 5HP 380VDC motor. Emco REALLY over built these. I figured I could get away with a 3HP motor since the machine is so compact. I have ZERO issue with going with a 5HP motor though.
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06 Jun 2013 18:25 #35331
by Zahnrad Kopf
John,
They are not quite table top, but not quite full size. They are compact, but full-on turning centers, very capable, and deadly accurate. ( very rigid ) Hence, my desire to keep it and retrofit it. Lemme see if this works...
Replied by Zahnrad Kopf on topic Stepper vs. Servo Question for Turning Center
I get the idea somehow that this is a table top lathe...
JT
John,
They are not quite table top, but not quite full size. They are compact, but full-on turning centers, very capable, and deadly accurate. ( very rigid ) Hence, my desire to keep it and retrofit it. Lemme see if this works...
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