"Very interesting. I wonder how easy it is to practically disassemble

large motors. I'd like to buy a smallish 3 phase motor one day for
next to nothing and take it apart to show my son how it works."


It is very easy to disassemble most motors. From my experience, (usually)
the end bells are an easy press fit onto the case at both ends. The end
bells are held in place with through bolts. Remove the bolts, usu. 4, and
mark the orientation of both end bells to the case. Start to break the end
bells' fit into the case by tapping with a narrow screw driver or knife
edge. Gently pry around the periphery until the bells seperate from the
case. After the end bells are clear of the case the rotor can be pulled out
from either end.

Most motors are easy to disassemble, but you'll find a few which are
horrible! Look for a motor which has end bells which are larger than the
stator, or at least end bells which have protrusions you can tap or
lever against. If the end bells are tight you can try heating the stator
gently with a heat gun, but this might damage the paintwork. If the
bearing seems to be tight in the end bell, you can warm the hub of the
end bell.

Most modern TEFC motors are straightforward to disassemble. You should
be able to disassemble and reassemble a motor without doing any damage,
so afterwards you can sell it on eBay or use it. On the other hand there
isn't a great deal to see inside a three phase motor.

A cool demonstration is to apply power to the stator without the rotor
present and put a coke can inside. Make an axle and handle for the coke
can so that it can't escape! You'll probably need to reduce the voltage
applied to the stator, partly to make it safer and partly to avoid
overheating the motor.

Chris