Instructables

Does anyone know how to make a homemade mechanism for a rotisserie that would turn a 125 pound hog?

I am thinking of using modified jack stands on the ends to hold up the spit or pole the hog will be on. I need something simple but safe. Thanks

swpoole10 months ago
made one using a gear-motor salvaged from a copier, a gearbox from e-bay and a few miscellaneous parts from surpluscenter.com and onlinemetals.com Check it out at http://www.youtube.com/watch?v=zJ1f7TLEno4
swpoole10 months ago
I made one using a gear-motor salvaged from a copier, a gearbox from e-bay and a few miscellaneous parts from surpluscenter.com and onlinemetals.com Check it out at http://www.youtube.com/watch?v=zJ1f7TLEno4
dblahnik2 years ago
I just picked up an old tread mill that im going to strip thse motor and speed control out of for this purpose. Not sure yet how I'm going to put it all together but but these motors are variable speed and seem to have a high tork . should work good :)
tall1smokey (author)  dblahnik2 years ago
That's a good Idea. As you go along making this could you send us some pictures or your rotisserie as your making it. I am curious about the torque too. Like you said , they seem to have high torque. I figure it can move with me on it (which isn't that often) it should move a whole hog.
Thanks so much for that idea.
http://youtu.be/chG9Urc0NHU

Ok it took awhile but check out this youtube link this is what i cme up with
just did a test with it today , I think it will work just fine over my fire pit
If you do a youtube search on hog rottisaries there are some people that have mounted a bicycle frame on a tread mill then ran a chain off the rear wheel gear up to the rottisarie. What I may do is just take a bike wheel and put a hub on the motor and just run the hub against the tire to spin the Wheel . I did that on a can crusher I built you can check that out on youtube (Double Barrel Bicycle Can Crusher) . Or you could also take the Tire off the wheel and get a long thin wide belt (cant think of what they call them rite now). anyway The motor already has the pully for those belts on it and I think the belt would run inside the rim of the wheel just fine.Just have to find a long enough belt . any who I have until june to figure it out .
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tall1smokey (author)  dblahnik2 years ago
Try going to you tube and look up redneck pig roast at davids farm. I don't know if I can do this or not but try this http://www.youtube.com/watch?v=2hXbTNfKBC0

Shows his home made hog roasting set up..\

Hope it helps you.
Anyone give me some direction towards a clock spring or pendulum type motor mechanism?
I think the critical quantity here is torque. I have drawn a picture of how I imagine this hypothetical hog on a spit. Different parts of its mass torque the spit in different amounts in different places. If the hog were perfectly balanced, then all these torques would sum to zero, and you could turn the thing using just your pinky. Of course that's never going to happen. There will be some imbalance,and some net torque. As the picture shows you can imagine this torque imbalance as coming from just one out-of-place mass, some distance from the center of the rotation of the spit.

BTW, the actual number for this torque will probably never be greater than the weight of the hog times one half its width. e.g. 120 lb * 0.5 ft = 60 ft*lb That's sort of the worst case, the most unbalanced you could get with the hog still touching the spit.

So you need torque. How do you get torque? Answer: mechanical advantage, something "geared down". a lot. The goal is to trade speed for torque, and the actual speed at which the spit will rotate will be very slow, ~ 1 rpm.

My intuition says to go with bicycle gears and chain, and then drive that with an old power-car-window actuator.
roast-pig-physics.png
tall1smokey (author)  Jack A Lopez5 years ago
Thanks for getting back to me. Someone told me that a car wind-shield wiper motor would work. Your drawing is good. I am looking for a close-up or how to hook the chain or what ever to the gears hook that to the motor and the rod to the motor. I can weld and I do smoke meat. I just need some help. Thank you for your time and your right I have to make sure the hog is balanced. I don't even know what speed the darn thing should go. Jack A. Lopez your the bomb....thanks
As an alternative to automotive servos (car-window, windshield, etc) another,maybe better, idea for the driver would be an electric drill. In fact old electric drills might be more ubiquitous, might have more power. Plus if it is a variable speed drill you maybe have a way of controlling the speed. Occasionally can find old cordless drills at thrift stores, or in your own junk pile. They're probably there because the battery died, with a motor and gears that are still good.

I'm glad you know how to weld, as I was imagining this whole thing made out of steel.

Regarding the question of how fast it should go, recall that power is torque times angular speed. P = τ * ω Convert the English units to metric first. Convert ft*lb to N*m and convert RPM to rad/s
1* ft*lb = 0.3048 m * 4.4545 N = 1.358 N*m
1 rev/minute = 2*pi/60s = (pi/30) rad/s = 0.1047 rad/s
The product of N*m and rad/s is power in Watts.
For the hypothetical example of 60 ft*lb * 1 RPM get
60 * 1 * 1.358 * 0.1047 = 8.5 W
And I think ~10 W is a good ballpark estimate of how much power you can get from your drill motor. So I think my earlier guestimate of 1 RPM for the angular speed of the spit is still a good goal to work towards.

I imagine gearing down the output from the drill with bicycle gears, and I have drawn a crude picture of this. I drew two gear sets, but you might be able to get away with one... or three... dunno that's for you to figure out.

gears.png
Im looking at doing this setup but befor i start the only question would be, If i was running the drill for a long period does the drill get hot. (I know when i drill many holes in things the drill does have a tendancy of getting warm.) or since there is very little load going on to the drill heat is not a problem? How long do you forsee could you run the drill for...? Sorry to be a pain but any coments would be fanatstic.


Yeah.  The drill overheating might be a problem,  especially if it were running at full speed.  At less than full speed, I'd think the heating would be less of a problem.  You know, I have not actually built one of these.  I was just throwing ideas out there.
Built one using a 23:1 gearbox from a photocopier and an 14:1 gearboxdirect drive on to shaft, fixed overhaeting problem with cpu heatsinks cut to 10mm wide bands and tied on with wire. moter still getting warm but fins seam to disapate quite well. Hasnt died yet...lol.
Well, I'm impressed! Good work!
My advice is to use a motor from a motorized icecream maker. The motor in those is made for high torque and, when torqued down to the point they won't turn (like when icecream has gotten so cold and thick that it can't be stirred any longer), they won't burn out like most other motors.
This one should get best answer just based on the drawing of the pig alone!
Hitlist4 years ago
well in Cuba it is a simple as driving some logs in the ground an putting some bracing on the top so it doesn't tip.On two of the poles where the spit pole will go through they tie two loops of rope.One on each pole.They slide the spit through these.Works as good as bearings when you haven't got bearings.They shove the spit  through the pig starting at the (ahem) back and coming out through the mouth.They sew up the pig to save juices and some steam.Drive a spike through the snout to the pole one through the back and finally one near the base of tail.Put a cross handle at end about six feet away from fire and sit back sip a couple and rotate slowly for three hours .To test for doneness and only do this once cut one or two small holes and if there is no blood coming out he is done.Let the juices drip into a pan away from the fire and add fresh crushed garlic and lemon or lime juice and serve over meat.Drool...keep it simple and you will find out what works and brainstorm while licking your fingers.
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spylock4 years ago
Hang the hog buy the hind legs with heavy rope,build the fire to one side,or even two sides,spin the hog on the rope and as the rope untwist it will rotate the hog,it works alot better than it sounds,many a turkey and chicken have been roasted that way in front of a fireplace.
This is also how the roast lamb and goat in many countries and in many Greek and Turkish delis.
I made one, started with a stone fire pit and pipes cemented in opposite sides. key ingredient for you though is gear reduction. the gear reduction boxes from the bottom of a snow blower work great. you may need 2 to slow down whatever motor you use. couple the shafts together with 3 point couplings. (northern tool .com, hydraulics section )  good luck
Made one once in Colorado for doing whole cows. We used 2" iron pipe (not galvanized!), pipe flanges and rebar for the spit. Mounted to the smoker using pillow block bearings and turned it with a combination of gears from an automatic transmission flywheel, Honda motorcycle and chain using a gearmotor purchased from Grainger I think. Worked well up to 600 lbs. The whole mechanism was attached to a Jobox (gang box) tool box with tip out trays for charcoal/wood. The bottom was cut off so the entire thing could be placed over an actual fire pit. I don't think I have any pics but once the parts are gathered, it doesn't take much imagination to put it together. As far as I know my ex-brother in law still has it and uses it regularly each year after roundup.
Ole bally4 years ago
Here's the rub! A rotisserie  takes ever such a long time to cook anything!
I understand this doesn't answer your question directly, but thinking outside the box sometimes is a good thing!
We regularly do a couple of sheep in our 'Mandela Microwave'. Regardless of how many we put in (up to 3) they all cook in about 3 hours!
We have taken an old 'leakey' 2000 liter overhead fuel storage tank and cut it in half along it's 'length'. Then at one flat end we made a couple of hinges outta pieces of pipe so that it can be opened and shut. like a drum barbecue. A couple of bits of pipe welded in place serve as feet to stop it from rolling.
But in essence, we 'spatchcock' the sheep and tie it onto a flat frame and then just by turning it over like a piece of steak on a regular barbie, the meat cooks in quick time.
The fire is made outside of the unit and the hot coals fed into the bottom with a shovel as needed. The lid is kept closed whilst cooking and it forms a sort of oven effect which speeds things up!
Just a thought for you!

mandela microwave.jpgmandela microwave 2.jpg
We used an old H.D. ratchet wrench slipped over a nut welded on the spit bar.  Add a length of pipe to the wrench handle for leverage, and you can 'ratchet' the hog over easily and control the position easily.  We used this to turn half a beef on a large outsoor spit and it worked wonders.  You stand off to the side and only lift the bar a bit and then push down one handed to turn the food.
d2j54 years ago
you can make a spit with handels that two people would need to move
mman15065 years ago
first i thought of a chainsaw engine bu then you'd have a gas lavoured hog and fire next to gas no good
Dr.Bill5 years ago
I'm going to make one out of a Wheelchair motor. They are 24v. and have gearboxes on them and can be had for FREE. When a powerchair repair facility replaces one of these gearbox motors they replace both of them. I find nothing wrong with the motors and the gearboxes can be resealed and regreased. Arrrr! They be free and will work on 12v.
Zilduli5 years ago
It seems like everyone here has a pretty good idea of what you should do but not many hints as how to do it. My suggestion would be to locate your nearest bike shop and ask someone doing bike maintenance if they have an old cassette (gear cluster from the rear of a bike), chain-ring (gears from the front of a bike) and some bike chain that you can have. Explain your project and maybe even offer to give them some meat. Once you have your cassette simply take a grinder to the pins that hold everything together. Once they are cut off your cassette should pull apart into many single gears and spacer rings. Hopefully somewhere within your pile of gears there will be a suitable ratio. In terms of a motor, I think something from an old treadmill would be perfect.
landmanhall5 years ago
You could also balance the mechanism after its mounted by adding weight at the other end of the rod. Think crankshaft. Make an instructable too!!!!!
caitlinsdad5 years ago
http://blog.makezine.com/archive/2007/01/rotisserie_buil.html shows something made from a washing machine motor. Those are actually difficult to wire up because they are not standard two-wire plug and go kinds.

It seems you need a lot of power to turn the spit. You would have to gear it up or use a belt drive with pulleys. Hook it up to an exercise bike. Good luck.