[pyroboby]

Hi all,

I have a 2hp spindle that I plan on running with a vfd and a few questions. First off, would it be possible the set the original speed control to the motors normal Tom's and change speeds with the vfd or would this cause torque issues. I'm not sure if my speed control on the BP even works as I've read of some having issues with the air spindle that helps with changing speeds.

Second, what vfd would you recommend? If I have to go the route of gutting the spindle controls I would need a sensorless vector drive for constant torque, correct?

If I haven't made my questions clear let me know, thanks all.

[keebler303]

Just seeing this, so I'll add my $.02.

You can set the varidrive to a nominal 1:1 ratio. If you need torque, you should still engage the low range gear. You'll have to remember that changes the spindle direction though!

I have heard of guys removing the varidrive completely and using timing belts. I think there is a guy on here making billet lids for them that eliminate the unneeded parts.

Any old VFD should work, sensorless vector will give you better torque at low speed. If you use the low range gear, you will have plenty of torque regardless. Most of the projects I have done with VFD's have been Baldor closed loop vector drives with encoder on the motor.

The general rule of thumb is something like 1/10 of rated speed for V/Hz, 1/100 for sensorless and 1/1000 for sensored. Even with a V/Hz drive at 1/10th of rated speed, you will be slower than the varidrive ever went (the varidrive doesn't give a 10:1 reduction). One advantage of a vector drive is better speed regulation so it would behave better when you go from cutting air to hogging into a piece of steel with a 1" rougher.

Matt