[Stoves] Question regarding motors

[joe breskin]

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-Drive-22A-V1P5N104-/270941251762?pt=LH_DefaultDomain_0&hash=يتيمعف١خخبطضبء
>>
>> 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