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Re: calculating bps for sync rsg..Thanks!

My comments at the bottom...

----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Saturday, March 04, 2000 2:58 PM
Subject: Re: calculating bps for sync rsg..Thanks!


> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
> At 09:16 AM 03/04/2000 -0500, you wrote:
> >In a message dated 00-03-04 08:15:34 EST, you write:
> >
> ><< Original Poster: "Jon Lagler" <rockcrawl-at-netzero-dot-net>
> >
> >> Thanks everyone for the responses! I am using a standard ac motor which
I
> >> have modified by cutting/grinding two flats on the armature. I guess
this
> >> brings the RPM up to 1800, and so I have 120 breaks per second.
> >
> >> Thanks,
> >> Jon >>
> >
> >Jon, the 1800 rpm motor should have 4 flats, and a 3600 rpm motor
> >should have 2 flats.  Did you check to make sure the motor is really
> >locked up?  I suppose it might be able to lock with just 2 flats, but
> >it probably doen'st lock as easily or strongly.  I don't know, I've never
> >done it that way and put 2 flats on a 1800 rpm motor.
> >
> >Cheers,
> >John Freau
> >
>
> Hi John,
>
> There is really no reason why this would not work.  Since 1/4 HP motors
> seem to have far more torque than is needed, the reduction in "locking"
> torque" due to using only two flats is probably not a big deal.  Since
> rotaries present constant torque, a small offset caused by lower driving
> torque would not be great.  The advantage would be the motor would draw
> less current and run cooler and the machining would be cut in half.  Of
> course, if it didn't work, one could always go back and cut the other two
> flats.
>
> Something to try on my next rotary....
>
> Apparently, this has been done before but I have heard little about how
> well it worked.
>
> Cheers,
>
> Terry
>
John,Terry, and all who are interested,
 I can assure you that my 1750 rpm motor is running synchronously (at 1800
rpm) with only two flats on the armature, and it has no trouble keeping in
sync. This may be due to the fact that the 1/2 hp motor has much more power
than needed, as Terry stated. This is the first rotary I have made, and I
made it with only two flats because I didn't know any better. Before the
modification, the coil would run in long surges, the sparks would
grow-shrink-grow-shrink....kinda neat actually. After grinding the flats (I
actually cut them with a reciprocating saw and cleaned them up with a
grinder), and proper phasing of the rotor, the coil runs at full power all
the time.

Thanks again,
 Jon Lagler
 New coiler in PA, USA

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