[Stoves] Question regarding motors

[Frank Shields]

Thanks all,

Lots of good info and likely saved a motor from what I was going to try!
Will see if I can find a set of belts pulleys and configure the right speeds I want. When the work comes pilling in I can then dish out the $$ and purchase the better stuff.

Frank

-----Original Message-----
From: stoves-bounces at lists.bioenergylists.org [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of joe breskin
Sent: Tuesday, May 29, 2012 1:03 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Question regarding motors

low friction loss infinitely variable speed is almost trivial to achieve using belt & pulley systems look at the drive on a powermatic drillpress

On Tue, May 29, 2012 at 12:00 PM, joe breskin <joe.breskin at gmail.com> wrote:
> On Tue, May 29, 2012 at 11:35 AM, Steve Taylor 
> <steve at thetaylorfamily.org.uk> wrote:
>>
>>
>> On 29 May 2012 20:27, Frank Shields <frank at compostlab.com> wrote:
>>>
>>> Stovers,
>>>
>>>
>>>
>>>
>>>
>>> I want to turn a frame holding solution of biochar along with 
>>> toxicants to determine up-take potential. Also to turn wood and 
>>> biochar  pellets to determine hardness. It needs to turn at 30 and 50 RPM.
>>>
>>> Can I use a ¼ HP motor with a Variac ? I have a motor ordered that 
>>> turns at 52 RPM (gearing included) and would like to fine turn it to 
>>> 50 rpm then, if it will not destroy the motor, adjust it down to 30 
>>> rpm with the same variac.
>>>
>>>
>>>
>>>
>> No, sorry, to assuming its an AC motor, you'll burn it out in short order.
>> AC motors tend to run at a multiple of mains frequency, or a shade 
>> off. When they are run under-voltage, then there isn't sufficient 
>> current to convert into torque, but enough current to convert into heat, and they'll burn up.
>>
>> For proper speed control, I recommend an AC inverter drive like this 
>> one from Ebay.
>> http://www.ebay.com/itm/Allen-Bradley-PowerFlex4-0-25HP-0-230VAC-Driv
>> e-22A-V1P5N104-/270941251762?pt=LH_DefaultDomain_0&hash=يتيمعف١خخبطضب
>> ء
>>
>> Steve
>>
>>
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>>
>
> my sense is that it will be cheaper and easier to 1. design around the 
> motor you've got 2. buy a gearmotor made to operate at the speed you 
> want, 3. add a secondary geartrain made with off-the-shelf part - 
> either gears, belts and pulleys, or chain and sprockets

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