[billsnogo]

I am just now getting the spindle turning on a bridgeport MDI retrofit. I am using a Hitachi wj200 vfd, single phase to three phase. The Bridgeport has the 2hp 2j head/motor, and according to the plate on it is 6.6 amps, 60 hz, 1700rpm (means four pole, correct?). From what I can find on the internet, if I run 120hz, it should spin the MOTOR at 1700rpm (full rpm of motor), but when I run 55hz, I get just under 4200rpm at the spindle(max rpm of the variable speed head). So, why can I spin the spindle to the rated max at such a low hz? Am I doing something wrong?

thanks in advance
bill (confused yet again)

[mactec54]

I am just now getting the spindle turning on a bridgeport MDI retrofit. I am using a Hitachi wj200 vfd, single phase to three phase. The Bridgeport has the 2hp 2j head/motor, and according to the plate on it is 6.6 amps, 60 hz, 1700rpm (means four pole, correct?). From what I can find on the internet, if I run 120hz, it should spin the MOTOR at 1700rpm (full rpm of motor), but when I run 55hz, I get just under 4200rpm at the spindle(max rpm of the variable speed head). So, why can I spin the spindle to the rated max at such a low hz? Am I doing something wrong?

thanks in advance
bill (confused yet again)

With using the Bridgeport variable speed, you should not go over 4,600 or close to this number

Your motor @ 60 Hz is going to run at 1700 rpm or close to it

If you set your VFD to 120 Hz your motor RPM will increase to 2,400 RPM, if you have all your Parameters set correct in the VFD, then if the motor did run at this 2,400, it would be to fast for your variable speed head to run at

Just as well the motor did not run up to the correct speed,you would get @ 120 Hz 5,900 RPM, this would not be a good idea for your variable speed to run at this speed, you may end up with a lot of spare parts flying around in the top of the head

Set your VFD to a Max of 70 Hz if you are running the variable speed drive

If you want to run faster than what your variable speed head can run, then you have to get rid of it, to do this with reliability, a lot of modifying of the head & spindle is needed

[billsnogo]

Nope, 4000rpm is fine for now. I don't even like the idea of spinning it at 4000rpm without an enclosure. Just not sure if I had wiring something backwards.

thanks!