On Thu, 16 Feb 2006 23:56:28 -0500, "Proctologically Violated©®"
ergo the distinction between variable speed/stepped pulleys moot (at least
w/ 3 ph motors)?
One thing is for su VFD is lot more expensive than stepped pulleys!
But mebbe the way to go, if there are no other disadvantages.
The only issue you have with VFDs..is lower torque at low rpms..and
possible heating issues if you are turning the motor too slow for the
internal fan to move much air. Which can be solved by adding a simple
muffin fan at the fan end of the motor.
Check Ebay for VFDs.
My Gorton Master Mill (step pully) is controlled by a Yuskawa PC-3
VFD. The belt is set on the middle pully and the VFD does all the
work, from dynamic braking (1 second stop from 5000 rpm) to virtually
instantanious reversing for tapping.
My nice big Rockwell drill press has an older Emerson VFD, which gives
me universal speed control
My little Kitakura second ops lathe (4C collet) is run by a Hitachi
1/2hp vfd, with universal speeds, instant reverse etc
I dont think Ive got $100 in any of the drives.
"A prudent man foresees the difficulties ahead and prepares for them;
the simpleton goes blindly on and suffers the consequences."
- Proverbs 22:3