[UKRobotics]

When people refer to a "spindle" does that mean just the bearing and shaft assembly i.e the business end or does it mean the motor as well ?

I need to replace the spindle motor on my bridgeport interact because it is rated at 400vdc and I dont have the ability to provide such a supply. The motor is connected to the front of the mill via a large belt.

The question is, will any 5hp 3phase 240v S1 rated motor do the job as a suitable replacement or will I have to buy a motor that has been specially designed for driving a spindle in the same way you get motors that have been specially designed to be used as servos ?

[Al_The_Man]

Get a three phase motor and VFD, if you dont have a low gear, you may run in to a problem with very low speed unless you get a higher quality flux-vector VFD or one with encoder speed control.
Also a cooling fan would need to be fitted for low speed operation.
The belt drive should also preferabally be timing belt.
If you buy a new motor, get a vector drive rated one.
Al.