Saturday 8 August 2009

A simple mechanism? I don't think so.

I have been working on my attempted reconstruction of Bessler's wheel for several weeks, on and off, and I'm finding that the mechanism is more complex than Karls' comment about the wheel being so simple a carpenter's boy could make one, might seem to imply. I think seeing a mechanism operating as a finished item is understandable and you can copy it easily enough so you could say it was simple - but making it up as you go along with only the barest outline of how it works, coupled with an understanding of the basic principe is much harder.

Firstly I found that making and fitting the mechanisms was not too difficult. Secondly, during this process I checked and rechecked their range of movement to make sure they operated as I intended - and they did. But (you knew there was going to be a 'but'!) once you raise the wheel to the vertical position in which it will run and allow the mechanisms to take up their natural position under the influence of gravity, it's then you discover you haven't got it quite right!

The mechanism has to do a certain thing at a certain time and getting that right is the hard part - I understand why Bessler complained about his own difficulty in setting the mechanisms correctly in his two-directional wheel but that was more complex than the single-direction ones. It tells me that he was a much more highly skilled engineer than I am.

Part of the problem lies in the way the various parts of the mechanism interact with each other. In my case I have a two foot diameter backplate on which to attach the mechanisms, but they take up approximately two inches of depth - I mean that they stand out from the backplate about two inches. I have redesigned them or rather rearranged them so that one lever is now operating under another one instead of over it and this has meant that I have had to increase the height (depth) above the backplate of the weight. This does seem to have improved the action of the mechanism so I continue.

I know this is difficult to comprehend without a drawing but I think you get the picture - it's proving difficult but not impossible to complete this project and definitely taking longer than I thought it would.

One point occurred to me; Karl's reference to a carpenter's boy suggests that the mechanism was made entirely of wood other than the weights? So the levers etc would be wooden rods I presume. I always imagined that it would have steel or rather iron levers.
PS Sorry, I forgot to say why it was giving me problems. In the first place the weights were taking longer to react to their changed position than I had anticipated so they did not create the reaction soon enough. That is not hard to fix, but the other problem was that the weights were catching one of the levers as I crossed its path and that required a change of the arrangement of the mechanism as I described above. This is not a situation where the design does not work because it is wrong but because the design does not allow clean uninterrupted range of movement .

JC

3 comments:

  1. Hi John

    Glad to read that you are still trying to finish the build.

    If the mechanisms were made from wood (perhaps now aluminium as substitute?) that too would probably alter the "free hanging" position of the weight, when the wheel is raised to its working position.

    I've found that the mass of the levers in a design mech that I have tried, often negates the effect that I was hoping for.

    I believe Bessler's use of ropes and pulleys is of importance here, in redirecting where a force can act within a wheel, without the mass overhead of the lever spoiling the design.

    Regards

    Mick (Mickegg)

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  2. So, you never said exactly why it doesn't work.
    Try leaving one lever 4 inches (for example) long, and another one 4 x 1.618.

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  3. I am using a division of 8 for the current wheel. I have finally been able to find long threaded tubing which will allow me to position the mechanism either close to the wheel or set off from the wheel by 4.5 inches. The length of the threaded tubing is 9 inches. and is supported on both ends. The tubing is used in the fabrication of lamps. I have spent a great deal of time trying to find a solution to the spacing problem as well........here it is

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