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Re: Grinding sync motors with an angle grinder :-))

Terry, all... pardon for a moment...

    WOOHOOO!!!! *dancing around the room*  yea, yea, I gonna grind
my own motor!

Okay, now that I got it outta my system :)  I've already tried the
angle-grinder method once and destroyed a perfectly good
motor...sooooo, I'll give it another try, following Terry's
instructions.  Mostly because I have no access to a machine shop
  But where 20 minutes of machine work will prevail, so will 3
hours of jig-setup and 1 botched attempt.


-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Friday, May 19, 2000 9:56 PM
Subject: Grinding sync motors with an angle grinder :-))


>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>Hi All,
>
> I cut the flats on both my sync rotary gap motors with and angle
grinder.
>A moment of silence will now be observed for all the "real"
machinists out
>there to scream in agony :-))
>
>. . . . . . . .
>
>Ok, the motors work just fine...  I pasted together a couple of
off list
>posts on my "technique" for everyone's information...
>
>The real plans are at:
>
>http://users.better-dot-org/tfritz/syncmot.zip
>
>
>Cheers,
>
> Terry
>
>-------------------------------------------------
>
>I just cut the flats on mine (rotor) about an hour ago...
>
>Mark the areas on the rotor you want to cut (or save) very clearly
with a
>black marker or something.
>
>Then cover the shafts and all the parts of the rotor (except the
areas you
>want to cut) with plastic tape (shipping tape) to protect them
from the
>metal dust.
>
>Clamp the thing in a vice so it is solid.
>
>Go rent, borrow, steal, or buy an angle grinder.  It has a heavy
duty
>flexible grinding wheel 90 degrees to the motor.  It is a hand
held metal
>cutter from heck.  See you Sears catalog for details.  Get a
couple of 60
>grit (or close) grinding disk for it too.  You can file the flats
by hand
>but it will take four years...  The grinder takes 1/2 hour if you
go slow.
>Motors are pretty basic iron things and you really can't screw up.
>
>Simply grind off the flats taking care to keep the grind flat
(hold it
>level) and stay within your cutting area.  Don't push hard and
just slide
>the cutter over the area in sort of a brushing motion.  It is
really easy
>and if you try to remove equal material, it will stay balanced and
all just
>fine.  When in doubt, cut less rather than more.  You can practice
on any
>chunk of metal.
>
>The rotor will get hot so you may have to let it cool down between
cuts.
>
>Simply remove the tape, clean it up, and your done.
>
>I had to add a shim to my motor because the shaft could move back
and forth
>more than I liked.  Mine used a 5/8 inner diameter fiber washer I
found at
>the hardware store.  It was only about 1/32 thick but it removed
all the
>play from my motor's shaft perfectly.  I just powered my motor up
and it
>runs perfectly and is in sync.  The current draw is 4.7 amps and
the motor
>is rated for 5 amps so It runs fine.
>
>1800 RPM motors really don't turn fast enough to have to worry too
much
>about balance as long as your careful.  3600 RPM motors are much
more finicky.
>
>My rotor is 3.2226 inches across.  I am cutting flats 0.850 wide.
My 1/4
>HP A.O. Smith motor has 36 metal chunks in the outer motor part
(not the
>rotor).  I am measuring from center-of-flat to center-of flat on
four of
>them.  There are three notches with the skinny wires in between
notches
>with the heavy wire.  The metal chunk with a heavy winding on one
side and
>a skinny one on the other is were you measure from.  I guess these
are the
>"half dead" poles. ;-))
>
>Cheers,
>
> Terry
>
>
>