Slowing down my rotiserie for pig spit

[kwwood]

Hey guys long time lurker here but decided to start to build my own pig spit and have had ok results so far. (see pics)



My current problem is in gearing down my electric motor. Unfortunatly the only thing I could find motor wise was an old GE blower motor that is 1/4 hp and does 1750 rpm. I am obviously looking to slow that rpm down. I have the chains from an old garage door opener but I do not think there will be enough gearing to get it down to the speed I need. I bought some inline power adapter thing that is supose to slow it down off ebay but that did not work. Does anyone have any ideas to get me started ie about how many gears I would need and any ideas going forward?

Thanks in advance for any help

You can see images here
http://imageshack.us/g/26/imagejpeg2pz.jpg/

I couldnt get them to link in the post.

[GeekSmoke]

What rpm are you looking for? Also, what is the manufacturer and model number of the motor?

[kwwood]

What rpm are you looking for? Also, what is the manufacturer and model number of the motor?

I am not sure on the specific model although I can look it up when I get home.
Here are the specs

Brand New Old Stock - Quality General Electric motor. Thermally protected, continuous duty. Specs: 115VAC 60hz, 3.5 amp, 1/4 horsepower, 1625 RPM. Rotation: CW (facing shaft). Shaft: 1/2" diam w/ flat x 1&3/8 inches long with flat. Weight: approx 9lbs Dimensions: 5.5"W x 8" tall x 6" long (Not including shaft)


As far as rpm I am not 100% sure yet. I am thinking less than 10 (maybe around 5-7) this will be my first time actually doing one and not just watching/being a helping hand.
Thanks

[DATsBBQ]

The weber rotissiere spins at 2.8 RPM

[GeekSmoke]

For a final drive speed of 5 rpm, you will need a gear ratio of 325:1. This means, that for a motor gear with 10 teeth, the load gear will have 3250 teeth. This is not very practical without a more complicated drive system. Also, you cannot use a frequency drive to slow down this motor unless it is designed for that purpose. It's windings are not built for it.

I would find a slower AC motor, or use a DC stepper motor that can be controlled with a simple motor driver.

[Papa Tom]

You can get a worm drive gear reduction unit that is what my roty has. It has the gear reduction box then a V belt drive with some additional reduction.

[kwwood]

You can get a worm drive gear reduction unit that is what my roty has. It has the gear reduction box then a V belt drive with some additional reduction.

Any idea where I could grab one? These mechanical things kind of escape me.
I already sunk 50$ into the motor, so if yall could recomend somewhere to get a variable speed one or point me in the right direction I would appreciate that.

[Papa Tom]

Here is what I'm talking about.
http://www.grainger.com/Grainger/speed- ... s2Z1z12j49

Now don't get discouraged over the price there are less expensive ones out there and there is always a used market. Maybe somebody will pop in with a source.

[danger831]

tell us where you are located some one close may have one for you also tell us how big and how much weight you plan to spin and will it be balanced.Some times when you start gearing a motor you end up with a lot more toque than you need you could possibly get away with a smaller geared motor.

[GeekSmoke]

Here is what I'm talking about.
http://www.grainger.com/Grainger/speed- ... s2Z1z12j49" target="_blank" target="_blank

Now don't get discouraged over the price there are less expensive ones out there and there is always a used market. Maybe somebody will pop in with a source.

Even at 60:1 reduction, he would still be looking at 27 RPM. Of course, he could drive a another gear and chain off of that at about 6:1, but that is going to get expensive quick.

Here is a Frequency Drive for high voltage ac motors. They sell them for low voltage motors also. Your motor may last a while with something like this, but the squared off sine wave will eventually overheat your windings. I have no I idea how long that will take at low rpms.

http://cgi.ebay.com/1-2HP-460V-GE-3PHAS ... 53de2503a0" target="_blank

[kwwood]

I am in the clear lake area.

I am looking at max of a 60lb pig. maybe eventually more (my roaster is 6 feet long) but seeing as this is me and my buddies first time we dont want to go too crazy but eventually would like to do it more often for football games etc.

Geeksmoke,
Would that Frequency drive work with a motor like this?
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 500wt_1413

Sorry for my complete lack of knowledge in this drive train realm.

Thanks for all the suggestions and ideas.

[GeekSmoke]

I'm sure it would "work", but if the insulation isnt rated at about H(180F), you may burn it out, and have a bunch of parts you can't use. I would scrap that motor, and find a smaller one. Like the previous post says, since you will be gearing down, you can make do with a smaller motor. Especially since you are only trying to turn a 60 lbs load, and not lift it.

I will keep hunting for a good solution. If you can keep away from variable drives of any kind, you will be saving a bunch of money.

[DATsBBQ]

Pricey stuff.
http://www.nextag.com/Bison-AC-Parallel ... rices-html
http://www.amazon.com/P55L-Whole-Rotiss ... B0044VKKCE

Might want to explore a powered by "arm-strong" set up?

[GeekSmoke]

Might want to explore a powered by "arm-strong" set up?

Or a windmill

[danger831]

or

http://www.amazon.com/Bison-Parallel-Sh ... pd_cp_hi_1