Slowing Down a 1/2hp Electric Motor for Hogs for the Cause

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Discussion Overview

The discussion centers around the challenge of slowing down a 1/2hp electric motor, originally designed to operate at 1750rpm, to a much lower speed suitable for turning a pig on a spit for a charity event. Participants explore various methods for achieving this speed reduction, including mechanical solutions and alternative motor options.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using gears to slow down the motor, indicating that simply using a light dimmer would not be effective.
  • Another participant humorously proposes roasting the pig at the motor's full speed, highlighting the impracticality of this approach without a perfectly balanced pig.
  • A worm gear is recommended as a simple solution to achieve the necessary speed reduction, potentially reducing the speed by 100 to 200 times.
  • Concerns are raised about the power requirements of the motor, noting that typical light dimmers may not handle the full power needed for the application.
  • One participant mentions the potential high cost of a new worm gear setup and suggests looking for surplus gear motors or automotive scrap parts as alternatives.
  • Another participant proposes using an old washing machine motor and drum, followed by a belt drive, as a feasible electrical solution for the task.

Areas of Agreement / Disagreement

Participants generally agree that a mechanical solution, such as gearing, is necessary to slow down the motor effectively. However, there are differing opinions on the best approach, including the feasibility of using alternative motors or manual labor.

Contextual Notes

Participants express uncertainty regarding the costs and availability of specific components, as well as the practicality of various proposed solutions. There is also a lack of consensus on the most economical or effective method for achieving the desired motor speed.

Who May Find This Useful

This discussion may be useful for individuals interested in mechanical engineering, DIY projects involving motors, or those seeking creative solutions for similar practical challenges.

Subaruzi
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I am in business school and every year we do a charity event called hogs for the cause (http://www.hogsforthecause.org/ ). This year we are planning on putting a pig on a spit and have designed the cooking apparatus. I have combed craigslist and found an electric motor that should be able to power the spit to turn. The problem is the $22 motor is a 1/2hp with a steady 1750rpm rate. Is there a way that I can slow that down to 6-10rpm? I was planning on using some gears but could I just throw a light dimmer on the cord and slow it down like that?

Any non-complicated, not very technical solutions are appreciated. I have a couple of engineers in my program so they could help out if you need to go super tech on me. Thank you in advance.
 
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No, you need to gear it down or be ready for a really fast pig.
 
Roast the pig at 1750 rpm.
 
gnurf said:
Roast the pig at 1750 rpm.

Don't try this at home, unless you have a perfectly balanced cylindrical pig. Otherwise your roasting pig may suddenly become a flying pig.

IIRC you can get cylindrical pigs from the same place as spherical cows...

Seriously though, the simplest gearing solution would be a worm gear which could easily reduce the speed by 100 or 200 times.

Using a light dimmer won't work, because you will need the full power of the motor to rotate a real, not-perfectly-balanced pig. In any case, 1/2 hp is about 400 watts of electrical power (including a bit of safety margin), and most devices sold as "light dimmers" won't handle that much power.
 
Thank you for the quick (and humorous) replies.
You guys have a worm gear supplier you could recommend?
I think that is the option to go with.
 
A, new, half-horse worm gear setup might cost more than a big surplus gear motor. Peruse this site for some painful realities: http://sdp-si.com/ or try searching for "surplus gear motor"...

Maybe you can find some automotive scrap -- transmission, differential -- parts that could be cobbled together? Or, given your big gear-down, a fairly small motor and a few step pulleys might be more economical.

ps...Aleph: nice reference to spherical cows
 
For just one pig, I think it could be cheaper to find a school boy who would do the turning manually for some pocket money.
If you really want to do it electrically, I suggest an old washing machine motor and drum could provide an appropriate drive, followed by a further (reducing) belt drive to the spit.
 

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