Re: better sync motor mods?

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

Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-uswest-dot-net>" <f-hammer-at-post5.tele.dk>

John, all

Very interesting observation, I have often been dreaming that it _might_
be better in some way, to make a narrow and deep slot along the rotor,
rather than the usual flat.  The reason that I have not tried it yet is
the one you mention: the risk of completely disrupting the current bars
in the rotor.

John, could you take a picture of that motor rotor, it would be
interesting to see the proportions of the whole thing.


Cheers, Finn Hammer

Tesla list wrote:
> 
> 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