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Posted by Pete C. on June 25, 2008, 6:39 pm
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I built a tumbler a while back that used a surplus Bodine gear motor
rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
build another one and I'm running into some confusion looking for
another surplus gear motor.
I'm finding gear motors with lower HP ratings but higher torque ratings
at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.
The connection between the gear motor and the final driven shafts is via
chain and I can readily adjust that drive ratio to get the final 50 RPM
shaft speed I need.
I'm a bit confused on whether the lower HP rating matters given the
torque ratings that are higher than I seemingly need based on the
original unit. Ignoring losses in the chain drive, that 1/12 HP motor
would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
HP one 131 LB-IN.
I must be missing something here...
Thanks,
Pete C.
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Posted by Ned Simmons on June 25, 2008, 7:21 pm
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wrote:
>
>I built a tumbler a while back that used a surplus Bodine gear motor
>rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
>build another one and I'm running into some confusion looking for
>another surplus gear motor.
>
>I'm finding gear motors with lower HP ratings but higher torque ratings
>at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
>RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.
>
>The connection between the gear motor and the final driven shafts is via
>chain and I can readily adjust that drive ratio to get the final 50 RPM
>shaft speed I need.
>
>I'm a bit confused on whether the lower HP rating matters given the
>torque ratings that are higher than I seemingly need based on the
>original unit. Ignoring losses in the chain drive, that 1/12 HP motor
>would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
>HP one 131 LB-IN.
>
>I must be missing something here...
Bodine often uses the same gearhead on a range of motor sizes, so
you'll find the torque on some of their geamotors is limited by the
input HP, and on others by the strength of the gears themselves. If
you're comparing worm gears to more efficient reducers, that would
also explain some of the discrepancy between input and output HP.
Ned Simmons
--
Ned Simmons
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Posted by Pete C. on June 25, 2008, 7:35 pm
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Ned Simmons wrote:
>
> wrote:
>
> >
> >I built a tumbler a while back that used a surplus Bodine gear motor
> >rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
> >build another one and I'm running into some confusion looking for
> >another surplus gear motor.
> >
> >I'm finding gear motors with lower HP ratings but higher torque ratings
> >at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
> >RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.
> >
> >The connection between the gear motor and the final driven shafts is via
> >chain and I can readily adjust that drive ratio to get the final 50 RPM
> >shaft speed I need.
> >
> >I'm a bit confused on whether the lower HP rating matters given the
> >torque ratings that are higher than I seemingly need based on the
> >original unit. Ignoring losses in the chain drive, that 1/12 HP motor
> >would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
> >HP one 131 LB-IN.
> >
> >I must be missing something here...
>
> Bodine often uses the same gearhead on a range of motor sizes, so
> you'll find the torque on some of their geamotors is limited by the
> input HP, and on others by the strength of the gears themselves. If
> you're comparing worm gears to more efficient reducers, that would
> also explain some of the discrepancy between input and output HP.
Possibly, I'm also thinking that the 11.0 LB-FT was really 110 LB-FT and
the "." was a well placed random ding. That would put the 1/6 HP 80 RPM
82 LB-IN motor at about the correct torque I'd think.
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Posted by RoyJ on June 25, 2008, 9:52 pm
Please log in for more thread options A quick calc shows 131 inch pounds for 80 rpm and 1/6th hp. With
allowances for gear and motor losses, 110 inch pound output would be
right on target.
Pete C. wrote:
> Ned Simmons wrote:
>> wrote:
>>
>>> I built a tumbler a while back that used a surplus Bodine gear motor
>>> rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
>>> build another one and I'm running into some confusion looking for
>>> another surplus gear motor.
>>>
>>> I'm finding gear motors with lower HP ratings but higher torque ratings
>>> at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
>>> RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.
>>>
>>> The connection between the gear motor and the final driven shafts is via
>>> chain and I can readily adjust that drive ratio to get the final 50 RPM
>>> shaft speed I need.
>>>
>>> I'm a bit confused on whether the lower HP rating matters given the
>>> torque ratings that are higher than I seemingly need based on the
>>> original unit. Ignoring losses in the chain drive, that 1/12 HP motor
>>> would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
>>> HP one 131 LB-IN.
>>>
>>> I must be missing something here...
>> Bodine often uses the same gearhead on a range of motor sizes, so
>> you'll find the torque on some of their geamotors is limited by the
>> input HP, and on others by the strength of the gears themselves. If
>> you're comparing worm gears to more efficient reducers, that would
>> also explain some of the discrepancy between input and output HP.
>
> Possibly, I'm also thinking that the 11.0 LB-FT was really 110 LB-FT and
> the "." was a well placed random ding. That would put the 1/6 HP 80 RPM
> 82 LB-IN motor at about the correct torque I'd think.
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Posted by Richard J Kinch on June 26, 2008, 1:49 am
Please log in for more thread options Pete C. writes:
> I built a tumbler a while back that used a surplus Bodine gear motor
> rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
> build another one and I'm running into some confusion looking for
> another surplus gear motor.
The Lloyd Sponenburgh ball mill design works great as a tumbler, and you
don't need a gear motor:
http://fogoforum.us/mill.php
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>I built a tumbler a while back that used a surplus Bodine gear motor
>rated 1/4 HP 96 RPM 11.0 LB-IN and it worked quite well. I now need to
>build another one and I'm running into some confusion looking for
>another surplus gear motor.
>
>I'm finding gear motors with lower HP ratings but higher torque ratings
>at similar RPM, such as 1/6 HP 80 RPM 82.0 LB-IN, or one that is higher
>RPM and higher torque, 1/12 HP 254 RPM 17.0 LB-IN.
>
>The connection between the gear motor and the final driven shafts is via
>chain and I can readily adjust that drive ratio to get the final 50 RPM
>shaft speed I need.
>
>I'm a bit confused on whether the lower HP rating matters given the
>torque ratings that are higher than I seemingly need based on the
>original unit. Ignoring losses in the chain drive, that 1/12 HP motor
>would seemingly give me 85 LB-IN at the shafts vs. 21 LB-IN, or the 1/6
>HP one 131 LB-IN.
>
>I must be missing something here...