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

[Subaruzi]

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.

 

[brewnog]

No, you need to gear it down or be ready for a really fast pig.

 

[gnurf]

Roast the pig at 1750 rpm.

 

[AlephZero]

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.

 

[Subaruzi]

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.

 

[schip666!]

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

 

[sophiecentaur]

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.