[Stoves] Calculating the RPM

[David G. LeVine]

On 02/12/2013 01:30 PM, Frank Shields wrote:
>
> Building equipment for determining the hardness of pellets and biochar 
> I need something to turn a 9 kg box at a speed of 60 RPM +/- 1.
>
> I have a 1/3^rd HP motor that is rated at 1725 RPM
>
> Fitted with a 2" pulley attached to the motor and going to an 8" 
> pulley gives me a shaft turning 431 RPM
>
> Then another 2" pulley going to an 8" pulley on another shaft gives me 
> 108 RPM
>
> I plan to adjust the 108 down to 60 using a voltage regulator.
>
> Is this a good plan?
>
> And is there another factor I need to include for the weight of the 
> box I am turning?
>

This is a BAD plan.

Your motor is probably speed controlled by line frequency, not voltage.  
Cutting the voltage may or may not help, in fact, it can fry the motor 
if the centrifugal switch does not kick out.

Get a 3 phase motor and a VFD and it will work well., but figure 
$100-$200 MINIMUM for the VFD.  The 3 phase motor will be fairly cheap.

Dave  8{)
-- 


/"Among the many misdeeds of British rule in India, history will look 
upon the Act of depriving a whole nation of arms as the blackest."/

Mohandus Ghandi, An Autobiography, Page 446.
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