Grasshopper Escapement – first steps

Sat, 25 Jun 2011

After all my experiments with ratchets and toothed wheels it is time to turn my attention to the escapement. The heart of many mechanical clocks, the escapement is the part that controls the time keeping. It has the dual function of driving the pendulum and dividing up time. There are a whole variety of different escapement mechanism from simple to complex. A quick search of youtube reveals many of them in action. After a bit of research I settled on the grasshopper escapement as an interesting mechanism that I thought I could recreate in paper.  

First, the escapement wheel. I settled on a purely arbitary thirty teeth as a compromise between the teeth being close together and the wheel not  taking ages to cut out. The wheel here is 120mm in diameter and made from doubled over card. To keep it flat I have added corrugations front and back at ninety degrees to each other. 

I've mounted the wheel and axle on a tall box. On the top I've added a hinge to attach the pendulum and the rest of the mechanism. The pendulum will hang round the back of the box. The rest of the escapement mechansim will attack to the front side of the pendulum hinge – more of that later. 

I had originally planned to wrap a paper strap round the axle and attach weights to the end of it. With the length of box I had chosen the wheel would turn just over two turns while the weight fell to the bottom of the box. Thirty tooth wheel, two and a bit turns, that would be around seventy ticks from one winding. By changing the weight so that it acted as a pulley I made it so that I got almost five full turns of the wheel from one winding. Almost 150 ticks!

This layout seem to work well though it will need to guides to keep the paper roll centred. 

Looking good so far. Next step, the actual escapement.

Comments (3)

  • umehta June 26, 2011 at 11:32 am

    Rob,
    Do you recommend a

    Rob,

    Do you recommend a digital cutter such as

    * Cricut
    * BlackCat Cougar/Lynx
    * Craftwell eCraft
    * BossKut Gazelle
    * Pazzles Inspiration
    * USCutter
    * Silhouette SD

    for cutting your amazing models? I just learnt about it from internet but have no experience using it and am wondering if it really works…I have a feeling that the investment could be worth to get a precision for the high end projects like your new Grasshopper Escapement…and yes, I would like to see this new mechanism fit and works with some real paper Grasshopper action! 

    Thank you,

    Urmish

    • Smelter June 26, 2011 at 6:06 pm

      I belive that Rob has (or use

      I belive that Rob has (or use to have) a CraftRobo.

      http://www.graphteccorp.com/craftrobo/

      I happen to have one but it does take some time program it from a PDF  file to get the cutting lines.

      Now if Rob was to publish a CraftRobo file for each of his creations I would rapidly run out of space to put all his models!

      • robives June 27, 2011 at 7:47 am

        I have indeed owned a

        I have indeed owned a craftrobo but sold it in the end. I used it occasionally but in the end the time needed to convert files and the fact that score lines were made by making a perforated cut line meant that I returned, in the end, to my scissors and knife. Video of the craftrobo in action.

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