sci.physics.electromag

"Robert Miller" wrote in message
news:8a56$4738f55e$6211824d$28589@ALLTEL.NET...
>
> "Benj" wrote in message
> news:1194888701.936803.58940@19g2000hsx.googlegroups.com...
>>
>> Robert Miller wrote:
>>> What is the inherent disadvantage if any to a stepper style motor scaled
>>> up
>>> to
>>> the 1/4 hp to 1/2 hp range. Using 16 to 24 NdFeB Disc, 1 in. x 1/4 in.
>>> 12,700
>>> Gauss or larger magnets with and 64 to 96 coils. Is the weight
>>> prohibitive?
>>> or
>>> some factor I haven't considered?
>>
>> I'm not sure why you are so stuck on stepper-type motors. Generally
>> speaking they don't come in high power ratings and tend to have lots
>> of disadvantages. The main advantage (you can digitally position them
>> without sensors) means little in your application as far as I can
>> tell. Even in large robots the typical thing is to use standard high
>> power DC or other motor and use position sensors to give positional
>> feedback for positioning them.
>>
>
> My reasoning is that I am more familiar with stepper motor design, I don't
> need more than 500 rpm, but I do need 1/4 to 1/2 hp. This would be a
> simple matter with a stepper type design, but I'm not ruling out other
> designs.
> Since I will build the motor myself I was think of keeping it simple
> provided
> there was not a much better alternative.
>
>
> Thanks again!

It's true I'm not concerned about the position of the motor except as a
function for timing and speed of the motor. I'll use a simple controler
for speed. My obvious downside is I intend to have 16 poles and that
means a great deal of wire for the 4 coils per magnet. In my working
model. I should get plenty of torque with 1 Amp per pole. My primary
disadvantage is that my battery life will be short. Little more than 2
hours.
I have taken that into account so battery life is not my primary concern.

Thanks again!

Robert
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