Has anyone converted Bridgeport Vari-drive to fixed ratio?


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Re: Has anyone converted Bridgeport Vari-drive to fixed ratio?

Post by CRM » Mon Jul 31, 2017 9:07 pm

The conversion is complete mechanically for sure, and nearly completely electrically (probably need to add braking resistors to the VFD). Servo tuning and VFD parameter tweaking need to be done yet. Then the move distance calibrations. I want to stop seeing the trial days counting down and buy the Centroid software first (I'm going to need it at some point soon anyway) which entitles me to a couple hours of remote support. Going to use some of that to get the servos tuned.
I recently learned that a knee type mill that had an old Anilam control on it in another department at work had been converted to a Centroid control. They replaced the servos on that one with AC drives. The thing is dead quiet when the machine is at rest with the servos powered. Mine (with Magnetek DC servos) "buzzes" and you can feel the oscillation in the handwheels on mine while the servos are powered on and the machine is holding position. The servos didn't do that with the old Prototrak control and drives; so I'll be pretty disappointed if tuning doesn't resolve that.
At any rate, a couple weeks ago I did make chips on it for the first time since disassembling it for the conversion 6 years ago...I cut a small 1/2" wide slot in a hydraulic cylinder rod for a tubing bender I'm building. But I confess, I was cranking handles.
Once cold weather forces me inside I'll get this thing across the finish line and be able to post some video of actual machining. :mrgreen:
Dean Jahnz
Cannon River Machine

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