[PhoenixMetal]

I recently purchased a Bridgeport mill with a 1J (step pulley) head and need to replace the motor because it was a Canadian machine and their motor configuration is not compatible with ours in the US.

I don't forsee any difficulty with getting a replacement motor (I have 3 phase power) however, I'm pretty sure I need to replace the pulleys as the canadian motor was running at 3475 rpm - wheras the US motors that I have seen run at 1750 or so RPM.

Does anybody know of replacement step pulley kits that are properly sized for the bridgeport?

Thanks in advance.

[79TigerPilot]

If the existing motor is a 3 phase motor why don't you just install a VFD that would most likely cover any motor differences between Canada and the US.

Craig

[PhoenixMetal]

I don't know if that would work - its not just a voltage difference between here and canada (240/480V vs 525V) - the motors are wired in a different configuration.

[seniormachinist]

If you're referring to the difference between 3 Phase delta and 3 phase Y, they are compatable.

SM

[Wade]

I know on big 3 phase motors, you never run the VFD much above 62hz, or the life of the motor will suffer. I doubt you want to run a 1750RPM motor at 120 hz. Even a small 2HP. It might not be too expensive, to just use a transformer to step the voltage up or down, depending on what you need. You can easily step 480V 3 phase up to 525V 3 phase. A 1HP motor is only pulling a couple amps.

[PhoenixMetal]

I ended up getting a used replacement motor (normal 220/440V). I haven't hooked it up yet so I have yet to see it work or if I have any pulley-related speed issues, but I will be needing to use the machine fairly soon. I will post my results once its up and running.