The Camping Rotisserie Project - Part 1
Jun. 2nd, 2012 10:48 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
hrjThis is going to be rather image-intensive, so it's behind a cut. Herewith is my stream-of-consciousness progress in devising a turning spit for my medieval camping fire-box.
So, two years ago at West/An Tir War, I bought a fire-box for doing open-fire cooking at events:
And it works very nicely for the purpose. But I'd always envisioned a set-up that would enable me to spit-roast meat, too, so I started thinking about possibilities and gathering together hardware to see what I could do about it. There were two aspects to the project: the apparatus for holding the spit, and some sort of mechanism for turning it.
The spits themselves were the easiest part of the task. I'd noticed in previous years at the Oakland Museum White Elephant Sale that in the kitchen appliances section they generally had a box of assorted rotisserie parts. In fact, I was able to pick up assorted spits and meat-spikes (or whatever they're called) for a song to experiment with.
The legs of the fire-box are 7/8" square tube stock, set in a 1" housing and fastened with an eye-bolt about 4" down from the top. This means that I could raise an extension for holding the spit(s) by inserting pieces of 3/4" square stock inside. They're a little bit loose. I could make them more secure by drilling a hole in one side aligned with the eye-bolt hole in the leg, so they're all held in place together. But then I'd have to disassemble the legs to remove the spit apparatus, and it might be nice to be more flexible. Right now I the spit-verticals are 3' long (the purchased length). That's way taller than I need them to be for spit placement, but since I'm not sure yet what I'm going to do for a turning apparatus, I'm going to leave the height at the moment in case it's useful. It's a relevant fact that the uprights aren't square with respect to each other, but we'll come back to that.
So how how does the spit interact with the uprights? Here's the longest of the spits I have to work with. It's just a little longer than the distance between two of the uprights.
And here's the shortest of the spits I'm playing around with: definitely shorter than the distance between the uprights. (The other two are a matched pair and fall in between those two lengths.)
One of my original ideas was that I'd simply run a long-shafted eye-bolt through the upright, with an eye large enough that the spit could turn in it even though it was at an angle, as you see here:
However this was awkward at best, would only work at all for the longest spit, and didn't take advantage of the fact that the spits all had a grooved "collar" at the head end to make turning easier. (At that end at least -- the configuration of the point ends differed and provide a different problem.) So then I started thinking: if I start with the assumption that the ends of the spit go perpendicularly through an eye-bolt, what sort of apparatus would I need to hold the bolt in the correct position and orientation? Holding the bolts where they needed to end up ...
... it became clear that what I really wanted was a couple of angle-brackets. This also solves the problem of the uprights not being square with respect to each other, because the eye-bolts will now hang downwards and can rotate into any angle they need to be.
Here's the long spit set up with the eye-bolts hanging from two angle-brackets. I currently have them just clamped on to the uprights. My first thought was that I'd drill holes in the uprights at various heights (to have options) and bolt the angle-brackets to them. Then I worried that I wanted to make the heights more finely adjustable since it makes a big difference for turnability if the spit is perfectly level, so maybe I'd need to use the clamps (at least on one side) to get that fine-tuning. But then I realized that the solution was in the eye-bolts themselves. You get the fine adjustment of the height simply by adjusting the nut. So I'll probably be drilling a series of holes spaced 1" or 1.5" apart.
Here's the same arrangement with the shortest spit, showing that it works for the whole range.
And from the side, showing placement with regard to the profile of the fire-box. All in all, it takes up a fair amount of the usable space once you visualize a piece of meat on it, plus maybe a dripping pan underneath. But then, you need the clearance for the whole piece of meat on the outer side, too. At any rate, the cooking logistics will simply be something I'll discover in use.
It is possible to move the spit a little closer to the edge if the angle-bracket is only bolted on at the top (which was my plan anyway) and then you stick a block of some sort (it only needs to be any sort of thing stuck through the lower hole on the angle-bracket) that holds it slightly to one side of the upright. I should have thought to take a close-up, but here's the difference in the profile. The spit is nearly directly in line with the uprights now.
Tomorrow I'll drill all the various holes and paint the upright with stove-blacking. (Keeps it from rusting.)
So at this point I have the design functional for holding a spit. The largest of the spits has a "collar" that won't fit through the eye-bolt so for that one I use an open hook-bolt instead, but in all cases, the rotation-collar also serves to keep the spit from "walking" out of its seating in the eye-bolts. The "point" ends would rotate better if I had some sort of round bushing I could set them into that would fit into the eye-bolt. (Ideally, I'd have some sort of bearing with an interior hole that would fit all the various shapes and sizes of spit-points. I'll keep my eyes peeled for something of the sort with a 1/4" bolt end. But in the meantime I'll just put up with a bit more resistance.)
The next big problem is how to turn the thing. I had a lot of fun today brainstorming with salespersons at various stores. A lot of times when you try to explain an SCA-related craft project to a salesperson you get blank incomprehension. But somehow the keywords "barbecue", "grill", "rotisserie", and "camping with no electricity" served to stimulate the imagination appropriately. The guy at Fry's in the mechanical toys and robotic servos aisle had a few suggestions, but finally agreed with me that the hobby kit stuff there simply wouldn't have enough power. He suggested I take a look at the mechanisms used in kid's electric "sit-in" toy cars. It might be useful for inspiration but I'm not sure I want to buy an entire toy car just to pull out and mod the drive motor. The woman at Home Depot (who I pitched the idea to with no particular expectation of success) suggested I look into cordless power tools (the 18V category). There would be some issues to overcome. On the plus side, the point of the spit would fit nicely into the chuck of a wrench/driver type tool and the tools are designed to be able to deliver high torque at low speed. On the minus side ... well, let's start with the visual of an obviously modern power tool right there in the middle of my cooking set-up. Also, the simplest place to locate the driver would put it rather close to the heat and I don't think that would be good for the tool. And perhaps most importantly, these are tools designed to operate on a "dead-man-switch" basis, i.e., to operate when you're pressing the switch, not on a continuous unmonitored basis. On a similar line, the drive speed is generally set by finger pressure. I don't know if it's even possible to set them up to run steadily at very low rpm all by themselves. So even if the power tool option is worth exploring, I think it needs modifications to move the tool away from the heat and maybe add in a drive train that steps down the rpm a bit.
Quite frankly, I'd love to be able to set up a clockwork mechanism rather than using battery power. One of the reasons for leaving the uprights a bit longer is to allow for the possibility of some sort of weight-driven turning mechanism. Even something that would run for 10-15 minutes between re-winding would work fairly well, given that the cook needs to be tending things consistently anyway. The big problem is that unless you get the spit-load precisely balanced, you need a drive mechanism that can overcome the imbalance. Of course, there's alway the option of setting a small child to turning the spit, but good help is just so hard to find these days!
So, two years ago at West/An Tir War, I bought a fire-box for doing open-fire cooking at events:
And it works very nicely for the purpose. But I'd always envisioned a set-up that would enable me to spit-roast meat, too, so I started thinking about possibilities and gathering together hardware to see what I could do about it. There were two aspects to the project: the apparatus for holding the spit, and some sort of mechanism for turning it.
The spits themselves were the easiest part of the task. I'd noticed in previous years at the Oakland Museum White Elephant Sale that in the kitchen appliances section they generally had a box of assorted rotisserie parts. In fact, I was able to pick up assorted spits and meat-spikes (or whatever they're called) for a song to experiment with.
The legs of the fire-box are 7/8" square tube stock, set in a 1" housing and fastened with an eye-bolt about 4" down from the top. This means that I could raise an extension for holding the spit(s) by inserting pieces of 3/4" square stock inside. They're a little bit loose. I could make them more secure by drilling a hole in one side aligned with the eye-bolt hole in the leg, so they're all held in place together. But then I'd have to disassemble the legs to remove the spit apparatus, and it might be nice to be more flexible. Right now I the spit-verticals are 3' long (the purchased length). That's way taller than I need them to be for spit placement, but since I'm not sure yet what I'm going to do for a turning apparatus, I'm going to leave the height at the moment in case it's useful. It's a relevant fact that the uprights aren't square with respect to each other, but we'll come back to that.
So how how does the spit interact with the uprights? Here's the longest of the spits I have to work with. It's just a little longer than the distance between two of the uprights.
And here's the shortest of the spits I'm playing around with: definitely shorter than the distance between the uprights. (The other two are a matched pair and fall in between those two lengths.)
One of my original ideas was that I'd simply run a long-shafted eye-bolt through the upright, with an eye large enough that the spit could turn in it even though it was at an angle, as you see here:
However this was awkward at best, would only work at all for the longest spit, and didn't take advantage of the fact that the spits all had a grooved "collar" at the head end to make turning easier. (At that end at least -- the configuration of the point ends differed and provide a different problem.) So then I started thinking: if I start with the assumption that the ends of the spit go perpendicularly through an eye-bolt, what sort of apparatus would I need to hold the bolt in the correct position and orientation? Holding the bolts where they needed to end up ...
... it became clear that what I really wanted was a couple of angle-brackets. This also solves the problem of the uprights not being square with respect to each other, because the eye-bolts will now hang downwards and can rotate into any angle they need to be.
Here's the long spit set up with the eye-bolts hanging from two angle-brackets. I currently have them just clamped on to the uprights. My first thought was that I'd drill holes in the uprights at various heights (to have options) and bolt the angle-brackets to them. Then I worried that I wanted to make the heights more finely adjustable since it makes a big difference for turnability if the spit is perfectly level, so maybe I'd need to use the clamps (at least on one side) to get that fine-tuning. But then I realized that the solution was in the eye-bolts themselves. You get the fine adjustment of the height simply by adjusting the nut. So I'll probably be drilling a series of holes spaced 1" or 1.5" apart.
Here's the same arrangement with the shortest spit, showing that it works for the whole range.
And from the side, showing placement with regard to the profile of the fire-box. All in all, it takes up a fair amount of the usable space once you visualize a piece of meat on it, plus maybe a dripping pan underneath. But then, you need the clearance for the whole piece of meat on the outer side, too. At any rate, the cooking logistics will simply be something I'll discover in use.
It is possible to move the spit a little closer to the edge if the angle-bracket is only bolted on at the top (which was my plan anyway) and then you stick a block of some sort (it only needs to be any sort of thing stuck through the lower hole on the angle-bracket) that holds it slightly to one side of the upright. I should have thought to take a close-up, but here's the difference in the profile. The spit is nearly directly in line with the uprights now.
Tomorrow I'll drill all the various holes and paint the upright with stove-blacking. (Keeps it from rusting.)
So at this point I have the design functional for holding a spit. The largest of the spits has a "collar" that won't fit through the eye-bolt so for that one I use an open hook-bolt instead, but in all cases, the rotation-collar also serves to keep the spit from "walking" out of its seating in the eye-bolts. The "point" ends would rotate better if I had some sort of round bushing I could set them into that would fit into the eye-bolt. (Ideally, I'd have some sort of bearing with an interior hole that would fit all the various shapes and sizes of spit-points. I'll keep my eyes peeled for something of the sort with a 1/4" bolt end. But in the meantime I'll just put up with a bit more resistance.)
The next big problem is how to turn the thing. I had a lot of fun today brainstorming with salespersons at various stores. A lot of times when you try to explain an SCA-related craft project to a salesperson you get blank incomprehension. But somehow the keywords "barbecue", "grill", "rotisserie", and "camping with no electricity" served to stimulate the imagination appropriately. The guy at Fry's in the mechanical toys and robotic servos aisle had a few suggestions, but finally agreed with me that the hobby kit stuff there simply wouldn't have enough power. He suggested I take a look at the mechanisms used in kid's electric "sit-in" toy cars. It might be useful for inspiration but I'm not sure I want to buy an entire toy car just to pull out and mod the drive motor. The woman at Home Depot (who I pitched the idea to with no particular expectation of success) suggested I look into cordless power tools (the 18V category). There would be some issues to overcome. On the plus side, the point of the spit would fit nicely into the chuck of a wrench/driver type tool and the tools are designed to be able to deliver high torque at low speed. On the minus side ... well, let's start with the visual of an obviously modern power tool right there in the middle of my cooking set-up. Also, the simplest place to locate the driver would put it rather close to the heat and I don't think that would be good for the tool. And perhaps most importantly, these are tools designed to operate on a "dead-man-switch" basis, i.e., to operate when you're pressing the switch, not on a continuous unmonitored basis. On a similar line, the drive speed is generally set by finger pressure. I don't know if it's even possible to set them up to run steadily at very low rpm all by themselves. So even if the power tool option is worth exploring, I think it needs modifications to move the tool away from the heat and maybe add in a drive train that steps down the rpm a bit.
Quite frankly, I'd love to be able to set up a clockwork mechanism rather than using battery power. One of the reasons for leaving the uprights a bit longer is to allow for the possibility of some sort of weight-driven turning mechanism. Even something that would run for 10-15 minutes between re-winding would work fairly well, given that the cook needs to be tending things consistently anyway. The big problem is that unless you get the spit-load precisely balanced, you need a drive mechanism that can overcome the imbalance. Of course, there's alway the option of setting a small child to turning the spit, but good help is just so hard to find these days!
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no subject
Date: 2012-06-03 06:44 am (UTC)no subject
Date: 2012-06-03 08:30 am (UTC)We turn our spit by hand and as we cook for 12 or so folks we never seem to have a problem finding people to turn it. Some times oddly even people who we are not feeding although that is only on cold days. As you shouldn't really leave a fire on its own anyway turning the spit never really bothers me.
Here is what we did http://jpgsawyer.livejournal.com/219128.html#cutid1
I found a local metal worker (mostly he fixes farmers tractors and weld beams for peoples roofs) and convinced him to make the raked uprights, staples and a spit. The uprights allow us to move the meat up or down to get the temperature correct depending on the meat and or the weather. In windy weather you will want something to shelter the fire or else all the heat is carried away by the wind and the meat doesn't cook. I have a simple folding screen for that.
Where possible you will want to have the meat not roasting over the fire but in front of it. This way you can catch the meat juices for later use and they don't just drop in the fire and burn. I find this and other combustion products cause a nasty taste on the meat.
Okay that was probably more than you wanted to know but this is my topic. :)
no subject
Date: 2012-06-03 03:18 pm (UTC)Two of the main reasons I'd like some sort of mechanical turning system are multi-tasking and space/crowding issues. When I'm cooking, I generally have 2-4 things going on simultaneously. So something where I could periodically wind up a drop-weight or give a flywheel a spin would put it into the rotation of tasks, whereas constantly turning it myself means I can't do anything else. The workspace around the firebox is also a little cramped. The limits on size have to do with what I'm wiling and able to tote in the car and lift for packing. I think my current set-up runs around 25kg, depending on how many of the accessories are stuck inside when I'm lifting it. So no more than 2 people working around it at a time is optimal (although it occurs to me that as long as the spit-turner is positioned "behind" the side that the spit is near, they wouldn't get in other people's way). I couldn't manage a suckling pig in the space -- probably not much more than a goose at the largest.
The external supports for the spit are an idea to consider, but I'd worry they'd get in the way when moving around the workspace. (See comments about multi-tasking.) When visualizing what I'm aiming for, it may help to keep in mind that the main type of event I use this for are what we call "cooks' play-dates" where a communal cooking process ("cooking as performance art" if you will) comes first and food production is (a very close) second. So I'm very often letting other people share the fire or even conducting mini-classes in the workspace. The equipment needs would be a little different if my main activity were doing production cooking for a large dinner and I was only responsible for one or two specific dishes.
no subject
Date: 2012-06-03 09:24 pm (UTC)no subject
Date: 2012-06-03 03:51 pm (UTC)