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Steps per w/ Dmm servo
« on: April 12, 2017, 01:10:06 PM »
How do I set steps per inch with Dmm sevos ? Ive done steppers but not servos.
The gear ratio is 2/1 46t/23t pulley . Im not sure of the ballscrew size yet im still looking . Its an older Sharnoa cnc .
Re: Steps per w/ Dmm servo
« Reply #1 on: April 14, 2017, 05:39:54 AM »
Hi,
the calculation is very similar. I believe the DMM servos are fitted with 10,000 count per rev encoders. With 2:1 gearing
the lead screw will turn one revolution per two servo revs, ie 20,000 pulses. If you leadscrew is 1/4 inch lead then your steps
per inch is 20000/ 0.25 =80,000 pulses per inch.

80000 per inch is pretty fine, if you wanted a rapid speed of 200ipm say then you would require travel of 200/60=3.33 inch/sec
or 266000 pulse per sec. A parallel port will never keep up in fact some external motion controllers won't go beyond 100kHz, others
will blaze along at 4MHz.

Should it be your controller be unable to deliver a pulse rate fast enuf for the rapids you have in mind you can use the 'electronic
gearing' function of the servo drive.

Craig
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     and I miss him!

Offline ger21

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Re: Steps per w/ Dmm servo
« Reply #2 on: April 14, 2017, 07:47:10 AM »
If you have DYN4 drives, it depends on what your electronic gearing is set to. Could be anywhere from 500 to 16,384, x2 for your gearing. (page 34 of the manual).
Then you need to know your ballscrew pitch.
Gerry

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