Re: making a motor synch?

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>

In a message dated 6/2/03 6:08:40 PM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:


>David,
>
>Understood, no centrifugal switch.  You probably made the flats
>wide enough, so the motor is probably just too weak as is.  You
>can try using a larger run cap.  Perhaps a 12uF or so.  These caps
>can be found in old air conditioners and other junked products.
>
>However, since the motor can't lock even with the spinning electrodes
>removed, this to me is a bad sign.  My guess is that it will never
>lock with the electrodes in place.  I've noticed that the grinder
>motors seem to be over-rated, for example a 1/3 HP may be only
>1/6 HP, so I agree with that.  I do know that a normal 1750 rpm
>1/4 HP or 1/3 HP induction motor with a centrifugal switch and
>start winding but no cap, can spin such a rotor with no problem.
>At 3600 rpm, a little more power is needed because of more air
>resistance, but still a typical 1/3 HP motor should be OK if it's
>either cap start, or has a start winding with centrifugal switch.
>
>John


There does seem to be something funny with the specs of some of these 
motors.  I built a sync rotary gap using a 1/25 H.P. 1800 rpm sync motor 
that I bought from C & H sales.  The rotor is 6.5" in diameter, 1/2" thick 
phenolic.  There are eight electrodes one inch long made from 3/8" diameter 
copper.  The motor seems to have plenty of power and locks into sync at 72 
volts.  This motor was purchased as a sync (hystersis) motor and not 
modified by me.  You can see it at my web site:
http://members.aol-dot-com/esondrmn/index.html

Ed Sonderman