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I Forge Iron

Need clock work type mechanism


Steve Sells

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I have decided to build a medieval rotisserie. rather than hire spit boys, I will be using clock work type gears and weighted pendulum to turn the spit.

Anyone have plans? experience with any Clock work mechanism, I have ideas, but would like some opinion from others before I attempt to reinvent the wheel.

Thanks

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well they used that type of mechanisim at colonial williamsburg but i dont know where you can get drawings for it ... looked like the gears were brass cast... good luck !


Yes, Peter Ross and his smiths built that one - there was an article on it in an old Anvil's Ring.
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There is plans and instructions for one in Joseph Moxon's "Mechanicks Exercises" published 1703 but mostly dating earlier. Note be sure you get the one containing blacksmithing as there has been a lot of excerpts re-printed that only deal with printing or sun dial making.
Astraegal Press did a complete reprint that I found a copy of in a used book store in Van Buren AR.

One of the neatest ones I have seen was in Muiderslot castle in the Netherlands. It was weight driven with the "spool" being wooden as I recall and had a series of springy wires mounted on it that were held down when the cord was wound up but when it was almost unwound they would spring out and start ringing a little bell telling you it was time to wind it back up. A simple extra that could be engineered in most designs I have seen!

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Steve, When I was 18 years old I made such a device. Got me a starter ring gear from a flywheel and welded spokes to a hub. Then I brought it to a machine shop and had the hub drilled and tapped. I threaded in a half inch shaft. Made an upright out of 3/8 x 1 1/2 flat bar with a sleeve bearing for the shaft. Turned a wooden hub to wind on a cord for the weight. Then I filed the gear teeth to a bevel to work with an escapement that engaged with the modified teeth and was mounted on the flat bar above the gear. Then i made a pendulum with an attaching link to the escapement. My escapement was of the rocker type, but if I were to do it again I would use another style of escapement. I have books showing different escapements. You may also have books showing these but if you will PM me I may be able to scan those that I have and send them to you.
Warren
I have post the two pages from this book showing clock works.

Edited by Warren Nakkela
Posted Illustrations
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12843.attach

12845.attach
Here are some clock mechanisms that may be of some help. I like the three toothed escapement for this purpose. This type will likely require a gear or other type reduction to the spit as it will turn one revolution with three swings of the pendulum.
Warren Edited by steve sells
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Steve,
It would look great if you could make the gears and escapement wheel out of wood. On the reduction pinion you could make a lantern wheel to engage with the wooden teeth on the gear. These could be as simple as hardwood dowels inserted in the gear wheel. Indexing the teeth around the gear will take some planning. What are you cooking on your spit? Mine was made for chickens and critters that size. I have made a spit for roasting pigs, but was power driven. (another story) If the spit is to be weight driven and regulated through an escapement the spit will have to be balanced. Movable counterweights will likely be needed . Expect to rewind the drive weights often. Light running bearings will be important.
Lubrication? You could use the drippings to grease the cog wheels and escapement. How much meat will be on the spit? This will determine the design.
Sounds like fun. Don't be pressured by any DEADlines.:o
Warren

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Steve
Just curious if you were just looking for a new project, or for a less labor intensive-no turnspit- for rotisserie/roasting. Participating in a living history group portraying the approx 1840 period, I have been cooking chicken, turkey, and ham on a string in front of the hearth fire. You only have to turn the cooking item whenever it stops turning. Depending on the length and size of the string, you may only have to turn the item every 5 minutes or so.

Jerry

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this project is for when I demo at ren-faires, I can have a chicken, or even a stuffed animal, on the spit turning to attract attention, and get conversation started and keep the marks, errr Clients around :D. Cant make the sale and get their money if they are walking away.

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I don't really know what the attraction is, but when I cook on the string for our annual historical fair, school field trips or at other times, it seems that some people become entranced when looking at the item cooking. Sometimes for 5 or more minutes. While I normally do this on the hearth, I have also used a tripod, the taller the better for less frequent attention to turning.

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