Clock weight design

Sun, 26 Jun 2011

Escapements are constructed from a collection of interconnected parts. Today, the weight.

My first draft didn't run very well. It stuck periodically as the weight moved down and the belt tended to drift to one side of the weight assembly. Today's draft, I narrowed the belt to 10mm from 20mm to reduce the friction. To keep the weight centred I added tabs on both side of the weight top.

As the weight drops down the belt slides under the curved surface at the top of the weight assembly. It still ran a little stiff so I thought I'd try adding a roller for the belt to roll over. It worked better even though the roller didn't actually turn. Weird. I suspect that the reduced diameter of the curve is reducing the friction on the belt making it run better. There are a couple of things I can try now. I'm pretty sure that the axle doesn't rotate because it is the proverbial square peg in a round hole. To make it work better I could use a cocktail stick as the axle however as I'm idealogically opposed to cocktail stick parts in paper models my alternative is to try reducing the diameter of the slip curve even further, making the weight assembly with no moving parts.

In other news. I've added a pendulum to the top of the box and added one of the two palette arms just so that I can begin to see how the geometry works. Looks like I can move the wheel up 20-30mm on the box.

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Comments (2)

  • najmanjay June 27, 2011 at 3:09 am

    hi rob,
    i was thinking about

    hi rob,

    i was thinking about your square peg, round hole problem. It reminds a bit of your excellent crank handle. I'm wondering whether you could modify your axle so that the part that is in contact with the square belt would have a round band around it. Conceiveably, the belt would move more smoothly with the round axle band than with just the square axle. You could also experiment w/the band and axle, to find out whether, if glued to the axle,  the easier movement of the band might cause the axle to rotate a bit. Let me know if you have already considered this option.

    can't wait to see the next installment of hickory dickory dock…:)



    • robives June 27, 2011 at 6:09 pm

      Hi Jay – interesting idea,

      Hi Jay – interesting idea, I'll give it a try. It is always worth knowing what ideas work for future reference!

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