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fmed
08-29-2005, 01:46 PM
Hi All...

First post here. I'm a total novice to fabrication, but I'd like to get my hands dirty on a pig roaster (not a southern style smoker, more or a Latin American/Filipino style Lechon roaster). It will probably use fabricated propane pipe burners.

My main design hurdle is the actual motorized mechanism for rotating the pig. I don't really want to buy an expensive gear-motor unit such as:
http://www.electricmotorwarehouse.com/rotisserie_motor.htm

I have a couple of surplus electric motors (1725 rpm. 3/4 hp, I believe). I plan to use an DIY electronic AC motor controller to get the speed down to about 10% (170 rpm)....that is still way too fast...it should be down to less than 10 rpm (the slower the better).. I'm thinking of then using (building?) a V-belt or chain reducer.

If anyone has any tips/plans/pictures of how they have devised such a thing, I would greatly appreciate it.

Thank you all!

fatfrank
08-29-2005, 02:20 PM
I have never built a rotisserie, but from what I hear the optimum RPM is about 1 RPM. Take photos of the build so we can check it out.

boilerman
08-29-2005, 03:21 PM
the ones i use are 110v ...it puts out 6 turns a minute at 110 inch pounds but i got it going to a larger sprocket on the spit and gear it down to 2 or 3 turns a minute...i can spin a 150 lbs pig no problem
you may also find this site interesting
http://www.3men.com/

fmed
08-29-2005, 03:50 PM
@fatfrank - Yes, my research also tells me that the ideal rotation speed is about 1 rpm....I have been racking my brains on how to do this without spending big money on a speed reducer gearbox or gear motor. I might have to resign myself to that fact. I found a place that sells a speed reducer gearbox for about $200 CAD (about $150 USD). I will post photos once I get started.

@boilerman - Does your motor have a gearbox built-in? Where did you get it? Do you have photos? Thanks for the 3men link.

Does anyone have any ideas on junkyard items that might work?

Thank you both for the replies.

boilerman
08-29-2005, 07:18 PM
yep gear box and motor are one ....i got it for 134usd few years back...look on grainger site for gear motors....if you look at the 3men site you will see the motor they use is the same as mine
http://www.3men.com/spitroasting.htm
all most at the bottom of page....my roaster looks nothing like that and i have mine geared down useing sprockets to give the motor more touque and slow it down more ...have to dig up some pics later tonight and post

moe1942
08-30-2005, 07:30 AM
Ice maker auger motors work great.

cutter
08-30-2005, 10:34 AM
Hi All...
I plan to use an DIY electronic AC motor controller to get the speed down to about 10% (170 rpm)....


I would like to hear more about this AC motor control.

stovepoker
08-30-2005, 11:30 AM
Be careful slowing down that 1725 rpm AC motor, fmed. There is a risk of overheating the windings and burning it out. You are better off with a gearmotor, they are easy to find. I run mine at a constant speed; I forget what that is but I'll check. Mine also has a heavy duty gearbox to handle the torque necessary for a 200+ pound load. I originally built mine for use with either gasoline or electricity since not all our cookouts were held in town.
If it ever stops raining I'll take some pics. I probably have an extra gearbox available if you can't find one down there.

stovepoker
08-30-2005, 11:32 AM
BTW, fmed, where ARE you located?

fmed
08-30-2005, 12:09 PM
@stovepoker: I'm in Vancouver BC. I am also concerned about the potential overheating problem. I have ordered the controller kit and I'll take a look at the circuit. If my guess is right, the circuit will pulse current through the motor for only a fraction of the cycle. I'm hoping that this might help to keep it cooler. I will also build a hand crank into the spit in case I fry the motor. :o

Thanks for the offer on the gearbox, please give me more details. I'm sure I can get the gearboxes locally, but they cost a mint. I've been looking around salvage yards - no luck (yet.)

@cutter: It is a kit made by Velleman and sold through Carl's Electronics:
http://www.electronickits.com/kit/complete/motor/vek2636.htm

Thank you all for the suggestions and caveats.

boilerman
08-30-2005, 12:19 PM
here is shot of my spit ....notice the sprocket on the endit is 3 times bigger than the one on the motor ... and the 2 plates behind it ....the plates are to keep the spit from traveling side to side and if you look close at the shot of the roaster in the back ground you can see the spit rests on a piece of pipe that is split ....i use fat from the pig and set in in on top of the spit in the pipe for lube

chumly2071
08-30-2005, 12:27 PM
another thing to consider is what type of ac motor you are dealing with. if it has a centrifugal switch to switch into and out of the start windings, simply slowing it down will cause all kinds of havoc... Most of the electronic speed controls I used to deal with (1 phase ac motors, anyway) were magic black box triac type controls that had to be used on a PSC (permanent split capacitor) type motor. gear motor or a sprocket reduction will be your best bet, I think.

cutter
08-30-2005, 12:30 PM
Okay fmed, thanks for the link.
I was curious to see if someone had come up with a controller for brushless AC motors. Nope. :)

Suggestion - and a request:
If you look at the upper right hand corner of this page, you will see that my location shows "Lubbock, Texas". We have found it to be a handy thing on this site for all members to post their locations in their profiles. (That way, Stovepoker would not have had to ask.) If you would please, look at the blue header bar with white letters, click "User CP" on the left hand side, click "edit profile", scroll down and fill in the "location" line, then scroll to the bottom & "save changes". We would appreciate it. City & province/state is sufficient. You will probably be surprised how often your whereabouts is relevant to the conversation.

And any of you other newbs that we haven't lassoed yet, please do the same. It is a custom we have tried to maintain here since the beginning because the nature of discussions here very often deal with where to get what or how to locate something nearby. Besides, we're just naturally nosey & like to know about you. :)

boilerman
08-30-2005, 12:31 PM
shot of it going in ...i looked for better shot of the motor but couldn't find one
it is the same motor as on the site 3men.....i just went with a chain drive and not direct...easier to slow down and speed up with just a change of sprockets ....the motor sits on a slide on side of roaster and can move up and down to engage the chain to drive the spit
the back of roaster has sliding door to regulate the air to the fire as needed ....and the fire stays in the back ...not under pig ....that way no grease fires...you can sit and relax with a beer or few while it cooks...if my friend come over with a digital camera and we get motovated i wil drag it out from behind building and shoot a few shots of everything...i build a twin to this roaster and the guy told me he did a 200lbs pig then stuffed it with chickens and the spit had no problem turning it for the 14 hours it took to cook

fmed
08-30-2005, 12:33 PM
@boilerman - Thanks for that pic. It's very helpful.

@chumly2071 - hmmmm....I nevered considered that centrifugal switch issue. I'll have to study up on motors. Unfortunately, the motors I have now are from parts unknown. Is there an easy way to tell if the motor is a PSC type? Neither of them have a capacitor now.

It certainly looks more and more like a gearbox is the safest route.

fmed
08-30-2005, 12:39 PM
Okay fmed, thanks for the link.
I was curious to see if someone had come up with a controller for brushless AC motors. Nope. :)

Suggestion - and a request:
If you look at the upper right hand corner of this page, you will see that my location shows "Lubbock, Texas". We have found it to be a handy thing on this site for all members to post their locations in their profiles. ...

Done! Sorry about that!

fatfrank
08-30-2005, 01:09 PM
Canada...................what are you thinking trying to build a BBQ in Canada. LOL

I guess you would need a pretty powerful motor to spin those moose on the spit. :D

cutter
08-30-2005, 01:14 PM
Fmed,

If your motor has carbon brushes, i. e., is a "universal" motor, then chances are that controller will run it. The better ones often have plastic or bakelite caps on one end 180 degrees apart that screw out to provide access to the brushes. On the other hand, the common fan-type motor that Chumly referred to is detectable when you turn it off; there will be an audible click when the centrifugal switch disengages. Or you can remove the bell cap from the end opposite the shaft & see the switch.

fmed
08-30-2005, 01:19 PM
LOL yes...we are certainly not known for our BBQ. Our loss though. Southern Style BBQ is getting to be more and more popular here...but it's nothing like what you guys can get at the roadside.

@cutter - Thanks for that tip. I will check when I get home today.

stovepoker
08-30-2005, 05:58 PM
Here's one that was built over 30 years ago. It is used year-'round, yep, even in January. This evolved from a wood-fired unit to an insulated staiinless steel lean, mean, ccokin' machine. Sorry it aint too pretty, and I hope none of the welds show in these pictures...

stovepoker
08-30-2005, 06:05 PM
Here's a shot of the gearbox. The input shaft is 5/8" dia and the output is 1" dia. It's an 1800 to one, so that means somewhere around 1 RPM with a 1725 RPM motor. The spit is direct coupled to the output shaft of the g'box, through a Lovejoy coupler and an industrial core chuck. Everything was made extra beefy to handle the weight of the critter being cooked. This arrangement could also be run with a small gasoline engine, for remote locations where electricity isn't available. Again, this gearbox can handle the torque of driving an out-of-balance load.

stovepoker
08-30-2005, 06:20 PM
Here's a shot of the spit. This also evolved over 30 years, from a straight bar to the 2-piece basket you see here. With typically one man running the show, it became a PITA to keep the food from slipping & turning on the shaft as cooking progressed. This arrangement holds the food firmly, and as the load shrinks with cooking, the springs take up the slack.
Also this split basket arrangement makes it possible to load the food without removing the spit. A decided advantage for one man handling a 200 pounder. The core chucks that support each end of this spit are positioned to release the shaft ends horizontally, so that the spit can be loaded and unloaded outside the cooker. A future improvement will add a folding stainless table directly in front of the spit, so the spit can be slid directly from the chucks forward onto the table. Thereby allowing the initial cuts to be taken at the cooker, and allowing any fat, drippings, etc, to fall into the cooker for transport offsite and future cleanup. Believe me, after a 36 hour stint cooking & serving a pig 100 miles from home, the last thing you want to do is clean up.
Usually I just want to close the cover and head home......

stovepoker
08-30-2005, 06:25 PM
Dang computers.....let's try this again....
BTW, there is an excellent way available to control the speed of an AC motor. It is called a VFD, or variable freq drive. In smaller horsepower ratings, they can be configured with single phase 240VAC input, and they will drive a 3 phase motor. These VFD's can be had for a couple hundred bucks, and we all know that small 3 phase motors are cheaper than poopcorn...

chumly2071
08-30-2005, 06:59 PM
cap start/cap run (two humps on the shell of the motor) are usually centrifugal switched motors. a PSC usually only has one.

Bolt
08-30-2005, 11:39 PM
It may be a bit bulky, but a pivot gearbox turns really slow, and is easily found (out here at least). With 2 sprockets, I'm sure you could get it to turn even slower, and get it down to the 1 RPM you talk about.

fmed
08-31-2005, 12:46 PM
@stovepoker: Wow! great pics....I have learned a lot by looking at them. Thanks for the tip on the VFD. I'll be Googling this today.


@bolt: "pivot gearbox" -- is this the common name? I tried to do a Google, but I couldn't find anything useful. Could it be called something else by industry?

Also I looked the link that WP88 provided earlier for a Surplus Center motor (http://www.surpluscenter.com/item.asp?UID=2005083008195598&item=5-1106&catname=electric). I noticed that it has a speed 'control winding' that takes 0-10 VAC. Does anyone here have any knowledge of how I can use this? Can I just use a regular step down power transformer (i.e., 115 VAC to 5 VAC) as a voltage source for the control winding? I did some Googling and now suspect that this could be a servo motor and may need a special driver/amplifier. Am I off base?

I know very little about electric motors (my other hobby is audio electronics, so I will eventually figure it out.)

Once again, I thank you all for bearing with me.

fmed
08-31-2005, 12:54 PM
cap start/cap run (two humps on the shell of the motor) are usually centrifugal switched motors. a PSC usually only has one.

Thanks chumly2071!

moe1942
08-31-2005, 12:58 PM
fmed, an ice maker auger motor is a very low speed, high torque motor. With additional gear reduction for speed control,it will turn anything you can get in your cooker. They are cheap and can be scrounged around here. All you need is an on/off switch. We use them here for our vertical coon *** pig roasters. They can turn a lot of pig without problem.

fmed
08-31-2005, 01:04 PM
fmed, an ice maker auger motor is a very low speed, high torque motor. With additional gear reduction for speed control,it will turn anything you can get in your cooker. They are cheap and can be scrounged around here. All you need is an on/off switch. We use them here for our vertical coon *** pig roasters. They can turn a lot of pig without problem.

Is this an icemaker from a regular household fridge? I'll do some phoning around today. Thanks for the tip!

moe1942
08-31-2005, 01:11 PM
Yes fmed. The motor/gear box that drives the crusher auger.

Incidetally we have modified the Lechon roaster here and it is called a coon *** microwave. We have the regular metal lined box but have the lid dished about four inches and heavily metal lined. We put the coals in the lid instead of inside. Talk about cooking some good pig ahhhyeee!!

The pig usually isn't turned in a Lechon or coon *** microwave so you must be thinking of modifying it also.

fmed
08-31-2005, 01:57 PM
Yes fmed. The motor/gear box that drives the crusher auger.

Incidetally we have modified the Lechon roaster here and it is called a coon *** microwave. We have the regular metal lined box but have the lid dished about four inches and heavily metal lined. We put the coals in the lid instead of inside. Talk about cooking some good pig ahhhyeee!!

The pig usually isn't turned in a Lechon or coon *** microwave so you must be thinking of modifying it also.

I found a source of these auger motors for $20CAD! Excellent....now we're cooking. Great tip!

Your design seems similar to the one used in the La Caja China (http://www.lacajachina.com/) "Cuban" style roaster. It's an interesting design. How do you baste? Does your lid slide away for access while cooking?

moe1942
08-31-2005, 02:08 PM
The lid lifts off. Takes two people for safety. Because the box is sealed and the coals are on the outside regular basting isn't required. The meat stays tender and juicy. The pig is rubbed and stuffed with all the usual stuff prior to going in the box.

Also the pig is on a rack so heat can circulate on all sides.

I think you will find the auger motor will work great.

fmed
08-31-2005, 02:14 PM
The lid lifts off. Takes two people for safety. Because the box is sealed and the coals are on the outside regular basting isn't required. The meat stays tender and juicy. The pig is rubbed and stuffed with all the usual stuff prior to going in the box.

Also the pig is on a rack so heat can circulate on all sides.

I think you will find the auger motor will work great.

With a sealed box, does the skin still crisp? (my mouth is watering as I type ;)

cutter
08-31-2005, 07:16 PM
I suppose it is a moot point by now, but I believe that Bolt was referring to the gearbox from a center pivot irrigation system. :D

moe1942
09-01-2005, 07:48 AM
fmed, the skin doesn't get cracklin crisp, but is moist and chewy. I like the skin too... :D

fmed
09-02-2005, 04:42 PM
Well I went over to the used appliance parts place that said they have icemaker auger motors....what they actually have seem to be actuators that push ice from the trays -- not motors. I drove around to other used parts places, but to no avail.

I'll keep looking.

fmed
10-24-2005, 11:07 PM
Thanks for all your help. Sorry it took so long to get back to you all. I ended up buying a Dayton gearmotor through a family friend who can get them at substantial discounts.

The roaster is a success. It can use both propane and charcoal. With propane the operation was nearly smokeless.

I met all my goals - the meat was and moist and tender. The mahogany skin was crackling crisp and devoid of blisters. It was all that I could have hoped. :D

Anyway, attached to this post are some early concept drawings and some photos.

Thanks again!

boilerman
10-25-2005, 12:35 AM
looks like you took some ideas from the 3 men site....looks to be one tasty hog there.....once you had pig done that way there is nothing equal to it...sex is close but you spill to much beer

LW Hiway
10-25-2005, 04:40 AM
Very nice looking pit. But how do you get the pig to sit still while you poke the rod......oh well never mind.....

Could you add a pic of the gear motor assy on the other end of the pit?

I've been waiting since early September for you to finish it and see what you decided on to use for the drive.

Job well done. "Bon apetitee' "

LW

moe1942
10-25-2005, 08:03 AM
fmed, you found out that parts people don't have to be smart. :D If you didn't live north of the border I could have sent you one. Glad it turned out OK .

Very nice job. Very professional as well. Did you do all the work or did you have help??

tonycamco
10-25-2005, 08:05 AM
what time is supper im starving

fmed
10-25-2005, 11:57 AM
Thanks for the kind remarks.

I had help from my uncle who is a pro fabricator. He did all the hard stuff and I did all the...."apprenticing". He works in a shop that has lots of gear - he bent the sheet metal there and drilled a few holes using their big drill. However, the most of the actual fabrication was done with hand tools. Nearly all the cutting was done with a Bosch angle grinder. My uncle is a genius with this thing.

I'll post the gearmotor assembly later tonight when I get home from work.

There were NO leftovers...it was a big hit with all my friends who are unfamiliar with this whole thing. :D

precisionworks
10-25-2005, 12:07 PM
Awesome job!

Now, if you have way too much left over, I'll be happy to give you my address so you can ship it here :D

fmed
10-25-2005, 08:43 PM
The motor is a 6 rpm unit from Dayton. It may be too fast for a pig rotisserie. I will probably make an intermittent timer to 'simulate' slower speeds. For the purposes of the trial run, I used a manual method...'on' for one second then 'off' for a bottle of beer :D

If I ever get around to building or buying that timer, I'll post details...don't wait around though..winter has set in Vancouver - I probably won't be roasting anything till late spring.

I have attached photos. You'll see that the motor is isolated using rubber washers. It also has a small hand-made (by my uncle) U-joint. The shaft is inserted into the stainless steel spit and locked by a nut.

Cheers!

boilerman
10-25-2005, 09:09 PM
that is the same motor i use on mine that i built 6 or 7 years ago...i slowed mine down by going to chain drive and reduceing the speed with sprocket... the motor is mounted on a slide plate and the spit rides above it ...slip chain on slide motor down to tighten and turn on

bgott
10-25-2005, 10:47 PM
Cutter, you can buy an AC motor controller from Harbor Freight on sale right now for $12 and change. I bought one the other day. They call it a "router speed control". Item #43060.