Re: Sync Motor Wanted

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

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

Hi,

Golly!  My 4" Makita angle grinder can do them a bit more "artistically" in 
like 30 minutes!!  The grinder has zero problems with the laminations but 
the aluminum in the casting can clog the grinder a little.  However, I bet 
with practice we all get a lot faster ;-))  The only thing that slows me 
down is the rotor gets hot so I let it cool off.

Thanks for sharing your experience.  Indeed, it appears that true machined 
motors might be too pricey ;-(    However, for what a machine shop would 
charge, you can get a big Harbor Freight* vice and a nice Mikitia 
grinder...  Making sync motor is not rocket science:

http://hot-streamer-dot-com/TeslaCoils/Misc/syncmot.zip

http://hot-streamer-dot-com/TeslaCoils/Misc/sync_motor.txt

BTW - Little milling machines cost just as much as big ones in the long run 
=:O  I wish I had more room...  But I can pick up the little one and stick 
it the trunk of my car ;-))

*Sorry to all the machinists for mentioning that place ;-))  I doubt I'll 
be bumping into Ed Wingate there :o))  Just think of it as a machinist's 
amusement park :-))))  And yes....  Their cheap twist drills really will 
"un twist" :o))  I did get a dial caliper from there the other day.  You 
may be confused!  Terry springs $250 for a Starrett caliper on Monday and 
$19 for a Harbor Freight caliper on Tuesday??  The Harbor Freight on is for 
(quite literally) underwater use ;-)))  They all have their nich...

Cheers,

         Terry

At 12:09 PM 4/17/2004, you wrote:
>Hello All,
>
>I had good luck cutting a rotor manual on a Bridgeport with a 2 flute Ti-N 
>high speed 3/4" cutter. Considering the 2 hours machine time (was being 
>cautious I suppose on the expensive motor) I'm not sure someone could sell 
>these at a low cost and avoid a loss.
>If anyone goes the milling route, I recommend climb milling to avoid 
>ripping out the laminations.  :-)
>
>I don't think steppers will have what it takes to run a good RSG, they 
>just have too many high-speed slip problems...
>
>Best of luck,
>Gregory
>
>
>>Original poster: Jim Lux <jimlux-at-earthlink-dot-net>
>>At
>>>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.
>>>
>>>>  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. :^)
>>>
>>>>  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.
>>>
>>>Ed Wingate RATCB
>>
>>If one wanted to sell 1/10-1/4 HP sync motors, they'd probably be better 
>>off finding a good off-shore (china, india) source and reselling than 
>>going to the trouble of buying induction motors and machining them. The 
>>machining to make a sync motor is the route you take when you get the 
>>motor almost free and you have lots of (low-paid) time, which is not the 
>>way to run a business.
>>
>>The other approach would be to find a source for big stepper motors and 
>>build an appropriate controller.  You probably don't want a Slo-Syn type, 
>>because there's too many poles, although, if you're driving it with a 
>>feedback controller, it might be ok.
>>
>>For that matter, some sort of DC servo loop might not be a bad way to 
>>go.  It's not like you're concerned about power efficiency, so the 
>>controller could be as simple as a straight Class A thing based on a 
>>2N3055 running a 24VDC motor.  Drive it with a simple PLL and an optical 
>>or magnetic pickup to sync to the power line.
>>
>>I would think that you could do it for around $20-30 in parts (excluding 
>>the motor, but including the PC board), which is certainly in a 
>>reasonable range (considering what folks are paying to  build SSTCs, for 
>>instance).
>>
>>In fact, given that the load is fairly constant, one might be able to use 
>>a 3450 RPM AC motor with a phase control type speed controller to run it 
>>at 1800 RPM. Or, a series wound universal motor (as in vacuum cleaners, 
>>angle grinders, and the like) could be controlled the same way.
>
>
>--
>"Without ZIM, I am lost."
>GeekID#-1229
>http://thegeekgroup-dot-org