Re: Sync Motor Wanted

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Ed,

At 07:54 AM 4/16/2004, you wrote:
>Tesla list wrote:
> >
> > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
> >
> > Hi,
> >
> > So folks offer MMCs and toroids...  But no "motor grinders" out there!??  I
> > know just the motor itself is like $100 new, but some people just don't
> > have the shop skills or tools...  It is a fairly trivial thing to people
> > that know what they are doing to grind, adjust, and test 1/4HP nice sync
> > motors "for sale".  Those of us that have many, will never sell "ours" ;-))
>
>Terry,
>
>Yeah, it's trivial, but time consuming. I have the necessary equipment
>to do the job, but how many would be willing to pay the $50.00 per hour
>shop charge on top of the $100.00 motor cost you state to have the work
>done?

That is the problem...  A lot of folks take the rotor to their local 
shops.  Not sure how economical it would be to make say ten in a row where 
setup and the logistics are already done.


>And grinding is NOT the way to do it. Especially if you're talking about
>hand grinding. A vertical mill is easier and will remove material more
>quickly.

I think of it as an art form :o)))  It is easier if one does not have a 
powerful vertical mill ;-))   The laminated steel is tough to mill right 
the first time by an amateur (guess how I know this ;-)).


> > Bill Wysock offers the entire sync gap, but his rock solid pro machine
> > prices are a little high for little guys.  For just the motor, you go out
> > and buy or find the usual 1/4 HP motor, grind the flats with a grinder,
> > shim the shaft if needed, be sure it is not terribly out of balance, and
> > maybe test it with a strobe as if anything could go wrong ;-)).
>
>Shim the shaft?

Most used motors, and some new ones, tend to have a lot of axial shaft 
play.  That makes it hard to get electrodes to fly close to each other 
without crashing, especially at startup and spin down.  So I shim that end 
play out.  Of course, one has to do it right so it will not bind when the 
motor heats up and all.  With shimming, one can use an old salvage motor 
too which vastly reduces the cost.

However, bring an old greasy motor the the machine shop for conversion is 
not reasonable.


>I've been selling complete asynchronous rotaries and separate rotors for
>many years now and the reaction from hobbyists on a budget when they ask
>for a price on a 7" rotary can be very interesting. Usually there is a
>longer than normal silence. I charge $650 for a complete 7" asynchronous
>rotary and that doesn't even reflect the true hours of machine and
>assembly time involved.

Cool!!  Do you sell converted motors alone?


> > After I finish my present giant project, grinding iron sounds relaxing
> > ;-))  But not for a few weeks yet...
> >
>
>Too bad motor armature laminations aren't iron, because that would make
>the job easier. They are silicon steel and are much harder on tooling
>than iron. :^)

Yep!!!  ;-))  They can also snag up and the laminations.  Chip can tell you 
about that :o))  Probably a cobalt cutter job.

>
> > Ok, I guess I am just a little surprised this cool part of Tesla coiling is
> > not a "buy off Ebay" (or anywhere else) part!!!
>
>I guess I'm not, because there's more involved than meets the eye and a
>very limited market.

I wonder how much people would be willing to pay for just the 
motor??  Perhaps the price would simply be too high and those that are 
willing to pay really would want to whole gap anyway...

Cheers,

         Terry


>Ed Wingate RATCB