I think that a more effective way to remove the shaft would be making a saw
cut into the rotor toward and inline with the shaft centerline.
I haven't tried this, but I wouldn't think that it would be necessary to
make more than one cut to release the contact pressure between the rotor and
shaft.

Silicon steel used for motor and tranformer laminations, that I'm familiar
with has been very soft steel, and not at all diffiult to cut.
The difference of an induction motor rotor is that there are the steel
laminations surrounded by a cast aluminum alloy (which is what makes up the
windings, or current paths, similar to a copper wound armature).
I believe the aluminum alloy would prohibit the use of an abrasive disk to
cut thru the rotor material.

I don't think that trying to drive a shaft out with a hammer will produce
much effect on the position of the rotor.

Polished sleeve bearings are very practical for numerous applications
(provided that they are lubricated properly). There might be an very
noticeable opening in the sleeve, referred to sometimes as the window, and
many motor housings will have an arrow or other indication of where the
window is located so the installer can apply the side load to a location
where the window is opposite the load side. The oil wick material might
contact the shaft thru the window for continuous lubrication.

On some older domestic USA motors, the manufacturer may have used cast end
end bells for the motor end plates that are very similar for both sleeve and
ball bearing models.
For the ball bearing models, they eliminate the extra material used for the
sleeve model, and machine a counterbore/pocket for the ball bearing
assembly.
This means that if a HSM discovers a good motor with worn sleeve bearings,
he can sometimes machine away the sleeve support webs in the end bell
castings to install ball bearings.
I've done this just to see if it could be done, and the results were as good
as if the motor originally had ball bearings.

This modification wasn't difficult to perform on a 9" lathe with 4-jaw
chuck, and the the cost of the bearings was only a few dollars.

--
WB
..........
metalworking projects
www.kwagmire.com/metal_proj.html


"Michael Koblic" wrote in message
...
In an effort to educate myself and hopefully gain a 3/4" shaft in the
process I attacked an electric motor I bought for $1 in a garage sale. It
has seen better days. I suspect it powered some sort of woodworking
machine as the whole thing was coated liberally with sawdust inside and
out. The insulation was rotten and falling off the wires. I should mention
that physically it was a big beast but only 1/2hp (the label was barely
readable).

I managed to get the front off. I expected ball bearings supporting the
shaft but there were sleeve bearings at both ends - the front one quite
chewed up which surprised me as the shaft seemed to turn freely. The
oiling port was plugged with sawdust.

I got the fan off and tried to get the rotor off but could not even shift
it. I should say I have never attempted anything similar and use of
Workmate and sledge hammer is probably not the recommended method. I
managed to mushroom the end of the shaft nicely but the rotor would not
shift.

The rotor sits on the central part of the shaft which is 1.25" as opposed
to the ends which are 0.75". There appears to be a small key in a slot but
trying to punch it out did not meet with success either.

Questions:

1) Are sleeve bearings usual in electric motors or is this some old, cheap
model?
2) Are shafts in such motor usually machined in one piece or is a 3/4"
shaft rammed into a mandrel to hold the rotor? In spite copious cleaning I
cannot tell for sure.
3) I am puzzled at the inability to shift the rotor. If the sledge hammer
did not do the job is a gear puller (or some other gizmo) likely to
succeed (as well as protect the shaft, of course)?
4) Am I missing some method by which the rotor is held onto the shaft
rendering the sledge hammer ineffective?

Books and Google have been no help. Neither was liberal application of
Liquid Wrench.

Thanks,

--
Michael Koblic,
Campbell River, BC