Re: Sync Motor Wanted

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

Original poster: G <bog-at-cinci.rr-dot-com> 

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.


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