better sync motor mods?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <FutureT-at-aol-dot-com>

Hello coilers,

I inspected an old small commercial GE salient pole sync motor 
and noticed that the cuts in the armature are not flats, but "V" cuts.
These V cuts are narrow and deep.  The top of the V is just half
as wide as the uncut armature portion.  I don't know if more modern
salient pole commercial motors are made this way.

Maybe the flats that we amateurs grind onto the armatures
are not the optimal shape for best torque, and cool running?
Maybe we have to make the flats rather wide in order to make
them deep enough?  If we used a V cut instead, we could make
them deep without making them so wide.  This may improve the
torque and let the motor run cooler.

Certainly it is much harder to produce a V cut than a flat, so most
coilers will probably want to continue using the flats which work
fine anyway.  But it would be interesting to try the V cut idea, 
which could easily be accomplished with a milling machine.
(It could be done with a hand file, but would be tricky.)  Perhaps
someone with a milling machine or access to one will try this
V cut idea.  For a true test, two identical motors would need to
be modified, one with the V cut, one with the flat.  To picture 
better how the V cuts look....the view from the end of the armature
looks much like a four leaf clover (maybe we'll be lucky too!). 

A possible problem with the V cut method is that it will probably
cut though some of the imbedded current bars.  Since these
bars are usually set at an angle, we may lose torque over a wider
portion than we hoped to.  Maybe the GE motor has the current
bars set perpendicular rather than angled to prevent this problem
(details, details).

Anyway, the V cut idea is something to ponder.  If the current
bar issue is a problem, then maybe a concave dish-shaped cut would
be better.  It produces a deeper cut for a narrower width than a
flat cut.

Mod'ing for max torque,
John Freau