Double crank with ninety degree lag

Sun, 19 Dec 2010

I've been working on an experimental mechanism that I hope to use in a few different possible models. The mechanism is based on a crank. In this crank there are two parts. Effectively there are two cranks one following ninety degrees behind the other.

This is the first draft box. There are two push-rods to which the character can attach. One push-rod is threaded inside the other. In the picture above, the right hand part of the crank (pink) is connected to the inner push-rod while the left hand drive (blue) is connected to the outer push-rod.

As the crank is turned, one push-rod moves up and down and the second follows slightly later, sometimes going the same direction, sometimes the opposite direction. The resulting movement is interesting and has a fluid feel to it.

Having worked out a first draft of the box I can see a few improvements that can be made. I'll implement them before I make the mechanism available as a download.  Meanwhile I'm working on a flash animation to show how this mechanism will work.

I haven't forgotten about the random motion Santa model. I've been experimenting but it still needs some work so I reckon it'll be after Christmas before its done. I'll probably use the mechanism for another model then produce a Santa version next year. Sorry folks. I'm sure it'll be worth the wait though 🙂

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Comments (1)

  • Nobledesign December 20, 2010 at 3:22 am

    Rob, this mechanism is

    Rob, this mechanism is especially interesting to me. It helps so much when you explain what the action is. It gets my mind working, thinking about what sort of paper figure actions I could apply it to.


    Keep these coming, please!!

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