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Author Topic: variable frequency spindle drive step and direction  (Read 3379 times)

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variable frequency spindle drive step and direction
« on: February 21, 2009, 04:19:44 PM »
hi all. i have an allan bradley 1336 impact variable frequency drive for the spindle on a hardinge chnc4 retrofit. the vfd has the ability to be driven with a step pulse. i have it connected with mach pin 8 outputting to the drive.index pulse is thru slotted disc on motor pulley.
the drive has  feedback from the existing heindehain 1024 encoder  . all i can say is wow! ask for 1589 rpm, get 1589 rpm. enter 472,
get 472.
after reading about others and there trials of getting the analogue set up, i was looking to that part of the retrofit with trepidation.up and running in 1/2 hour.

anyone else using step pulse with a vfd?


Re: variable frequency spindle drive step and direction
« Reply #1 on: February 21, 2009, 05:07:29 PM »
Yes, that's a very good set-up. Anytime you can have a closed loop, you have super control. Most VFD's that I have encountered are analog voltage control although the one I have does have an option that can be purchased for an optic  speed feedback. The main reason I bought it was for that feature but feeding it with step and direction is not there and the feedback system is almost as expensive as the VFD.

I was involved with a conversion of a Zayre/ Hiedenhime (sp) milling machine to a Fagor Operating system that was basically built around the machine's feedback systems. It had glass scales that were utilized for feedbacks for the axis drives. Only machine I ever saw that was repeatable in 3 meters to a tenth at feed upper limit.

Bill C.