Re: Heortling Mills

From: rmv1_at_...
Date: Tue, 20 Mar 2001 16:43:20 -0000


[Andrew Barton and Bryan Thexton continue the excellent thread on Sartarite windmills.]

Andrew Barton wrote:
> It's a fallacy that you need to know a good numerical value for pi
> to make things.

Absolutely true! If you get a chance to read the History of Pi by Peter Beckman or the more accessible Joy of Pi by David Blatner (can't recommend this one highly enough; easily readable by mathphobics) you can find all kinsd of examples of people building complex structures without the value of Pi. Some ancient societies used a more accurate approximation than our 22/7...

Bryan Thexton wrote:
> One more thought about gears....you are putting a lot of force on
> them if you are driving a large grindstone. How well will bronze
> hold up to this (as opposed to iron)? I suppose if you make the
> teeth broad enough, and use very thick cogs, you could probably get
> the mechanical strength you need, but that makes them even harder
> to manufacture, and probably much noiser (the larger teeth will
> tend to hit harder than will small teeth).
You don't make the gears out of metal. The gears in the old postmills  were made of wood. Instead of having a metal disk with cutouts along the edge, picture a wooden disk with little wooden pegs driven into the edge. The nice thing about a wooden gear wheel is that it is more modular than metal. You need to replace the gear that sits on the windshaft? No problem, you can take another gear that is the same size, pound the pegs into the top of the disk instead of the side, and voila! You'd be surprised at the stength of wood. It is more than up to the task, especially if it is allowed to weather and the proper hardening treatments are used.

Roland

"Modern Engineering is learning to use the same size hammer to pound progressively bigger nails."

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