[Prev][Next][Index][Thread]

Grinding sync motors with an angle grinder :-))

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