Synchronous conversion of a 5 hp 3 phase 220/440 1.25sf 4 pole motor.
Rotor diameter is 120mm, lamination stack is 5.25 inches deep/long. (works out to a nominal 4.75" stator internal diameter, with a .35mm air gap, or .013 inches
"back iron" behind the coils is only 15mm thick, thickness of the stator core is 35mm, so the slots are 20mm deep.
I have no intention of destroying the rotor, so my tentative plan is to make a new one.
Given the 15mm thick back iron, the rotor will require twice that for the salient pole core.
Conveniently this is the same as the 30 and close enough to the 28mm wide core of larger than average microwave oven transformers. Presuming I can take the E cores, and cut a dovetail in the center leg of the "E", press the core onto a shaft, then cut the E core down and end up with a "T" shaped core with a 60mm radius cut into the top of the core, then i should be able to get a rather legit core for very little effort. (on the other hand i threw out 30 pounds of microwave oven tx cores a month or three ago, so i don't have enough on hand to do this tomorrow.. so.. Alternatively I could attempt to make a stator from solid steel.. but i'm not sure i will have the measurement capabilities to extract the rotor core losses from such a system.)
the motor is pressed into an extruded aluminium case, so i expect the saturation losses to be a bit of a sharper brick wall than i have noticed before..