2005-04-15

HOWTO Build Your Own Bicycle Rotisserie: Part I

A couple of years ago one of my good friends married a very nice young lady at a lovely ceremony in his back yard. Dan is Jewish and wanted to have a kosher wedding feast, which meant, among other things, that food had to be prepared at the house (well, strictly speaking, any kosher kitchen, but those aren't very common outside the Jewish community). I'll let Dan explain:
When Dan's parents first moved to Fargo, ND, they celebrated their new home by roasting a whole sheep--a gift from the NDSU agriculture department--behind the house.  Dan loves the pictures of this event, and is only sorry that he was too young to appreciate it.  To compensate, he'll be re-enacting the affair, roasting a whole kosher lamb (actually, six forequarters of lamb).
Anyway, we needed some way of actually roasting said lamb parts. I should say Dan needed some way of roasting said lamb parts, but he's quite good at getting other people to do work for him. Real management material, that Dan… So in any case I was charged with the responsibility to devise a device to roast eight 20-pound forequarters of lamb on the wedding day. No pressure… Now the first thing any sensible engineer would think is "outsource." Not as in rent-a-coder outsourcing, but as in "buy something off-the-shelf that will work." But it turns out the only thing really commercially available is a pig roaster, which just doesn't quite cut the mustard in the kosher department. It also carried something like a $150 per day rental fee. So the next thing any sensible engineer would think of is "improvise." Any improvisation, however, would have to have a relatively low likelihood of resulting in catastrophic collapse, since we're talking about the main dish here. I don't remember the exact thought process, but somehow I hit upon using a couple of old bicycle frames to do the heavy lifting, as it were, in building the rotisserie. It turns out to be a relatively ideal solution in case you need to crank out a sturdy rotisserie in your spare time given a month or so to prepare. The advantages of this approach are manifold, but primarily they are:
  • The bottom bracket is designed for a heavy-duty offset load
  • You get built-in gearing (or as my friend Craig would say, "it come widdit"). If you run a belt around the rim of the rear wheel, you get an even greater gear-down.
  • The seat posts allow for height adjustment
  • Useless old bicycles are available nearly free of charge
What you'll end up with is both bicycles upside-down, resting on the fork and the seatpost (with a little "foot" attached). The spit will run from one bicycle's bottom bracket to the other's, and one of the bikes will have a belt driving it's wheel (sans tire), which will in turn drive the spit using the bike's chain. So here's what you need:
  1. Two bicycles of roughly the same (preferably small) size, and permission from the owner to render them useless (as bicycles anyway). I used a couple of Murray kids' mountain bike frames
  2. A spit -- one-inch-diameter (preferably stainless) steel is ideal, with a wall thickness around 1 - 1.5 millimeters
  3. A few scraps of steel, such as tubing, I-beams, or angle iron
  4. A hacksaw or reciprocating saw with a metal-cutting blade
  5. A welder and associated paraphernalia
  6. A drill with a 1/4-inch bit
  7. A pair of 1 1/2-inch 1/4-20 bolts with nuts and washers
  8. Fire!! Fire!! heheheh
Now that I've teased you with the ingredients, I'm going to end Part I. In Part II I'll talk about how to put the thing together, and in Part III discuss the actual logistics of cooking with it.

1 Comments:

At 12:09 PM, Blogger Silvester said...

This is AWESOME! do you have any pictures you can email me, I would like to reproduce this for my neighborhood block party. also if you have a part III that would be much appreciated. You can email me at bernhardt00@gmail.com. thanks!

 

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