Re: Sync Motor Wanted

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

Original poster: "Arpit Thomas" <arpit-at-inzo-dot-org> 

How preceise do you need to be in  grinding the flats? I couldn't really 
find much info on the web about this. I tried grindding flats in a 
microwave oven fan shaded pole motor but the rotor wouldnt even fit back in 
after I finished *sigh*

*********** REPLY SEPARATOR  ***********

On 17/04/2004 at 9:03 AM Tesla list wrote:

 >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.