Re: Sync Motor Wanted

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

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

Hi Ed,

At 01:04 PM 4/16/2004, you wrote:
>Tesla list wrote:
> >
> > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
> >
> > Hi Ed,
><snip>
> > 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.
>
>Just trying to explain what you want and why, to a local shop, can be an
>exercise in frustration! Synchronous rotary spark gap is NOT a common
>term and can garner some strange looks and comments.

Indeed!  Rather than making nice drawings with all the stuff they really 
need to do a job right, it might be faster and easier just to hand file the 
rotor ;-))  I know a machine shop owner who is cool about weird projects, 
but most normal shops would require a lot of explanation.



>OK, you do the art form and I'll opt for ripping off as much metal at a
>time as possible. If the chips aren't landing six feet away, the machine
>isn't working. :^)

The web server computer sits two feet away from my little milling machine 
;-))  So I have to watch metal chips pretty carefully (of course, if (when) 
it crashes, I blame it on MicroSoft in any case ;-))  If I had a big mill, 
I would use it :o))

>
> > >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.
>
>That's why I've always used and recommended ball bearing motors. No end
>play to contend with.

Most cheap 1/4 HP motors are going to be sleeve shaft.  No problem at all 
to shim them a little.


> >
> > Cool!!  Do you sell converted motors alone?
>
>Hold on. I sell ASYNCHRONOUS rotaries.... and "separate rotors" in the
>above paragraph means balanced rotary gap rotors complete with tungsten,
>not motor rotors.

Ok.  Since you have pig powered systems, ASYNC is fine.  Those of us trying 
to drag every bit of power out of a NST love SYNC since we can play the LTR 
game.  IMHO, rotary sync gap LTR is the best out there for NSTs.

> >
> > Yep!!!  ;-))  They can also snag up and the laminations.  Chip can tell you
> > about that :o))  Probably a cobalt cutter job.
>
>Judging from past posts and the above, you seem to have a thing for
>cobalt. Cobalt alloy tooling is only marginally better than high speed
>and not really worth the cost.

Try cutting 6-4 titanium with tool steel :o))  I just get the hardest bits 
I can since that will do everything no matter what.  In my case, they last 
forever since I will never use them hard enough to dull the cobalt.  Of 
course, machine shops have to worry with the economics, but not a concern 
here.  But nowadays, most of my titanium (and phenolic) cutting is done by 
the waterjet shop...

>I never used cobalt in the Rapid
>Prototyping Center where I worked at The Big Yellow Box, it was either
>high speed or carbide. On the subject of machining, here's one for you
>to ponder. :^) Carbide cutters are the only kind to use on 99.9% of
>plastics.

Plastics (like high-grade UMHW) need super aggressive super razer sharp 
cutters.  I do use two flute tool steel for that.  Maybe I need to look 
into carbide instead since the steel does dull.  I tend to break carbide 
(maybe I should not use them in the hand drill so much :o)))  Cobalt is 
very strong but you have to jump into the fox hole if they do shatter!!  I 
always get Ti-N coating too which is worth the cost.  Shopping for the 
mills is easy too, I just look for the most expensive ones ;-))  But in my 
case, the cutters are the cheapest part of the whole milling thing.  My 
brand new Starrett 12 inch calliper just set me back $250!!  Hey, gota have 
it :o))

Cheers,

         Terry



> >
> > 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...
>
>That's a very good question. TBD.
>
>Ed Wingate RATCB
>
>P.S. In another post about my palm sized coil the transformer voltage
>was left out, it's 20 ma/ 2 KV.