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Further experiments on the theme of pendulums. I really wanted to create a pendulum powered model that bobs up and down when it is moved. Obviously, the first person that sprang to my mind when thinking about this possible mechanism was Ada Lovelace, mathematician and steam-punk computer programmer. And so we have, forthcoming project of a pendulum powered Ada Lovelace who bobs up and down whenever she is moved. Perfect.

Okay, mechanism time.

If I could use springs a vertical moving pendulum would be trivial but with card it is less straight forward. I need to convert the back and forth movement of a pendulum into up and down movement, and all within the space of Ada's conical section skirts.

My first draft is shown below with a bit of explanation as to why it was unsuitable. And so onto mk2. The go-to mechanism to change direction of movement by 90 degrees is the bell crank. The problem (there is always a problem, that is where the fun comes in :-)) being that the bell crank necessitates extra width in the model, making it hard to fit everything under the skirts. Above right and centre are my proposed solutions. Firstly, a pendulum with a cut out in the centre. Secondly, a bell crank that doubles back through the hole in the pendulum wrapping the mechanism neatly in on itself.

Notice also that I'm linking to the end of the main pendulum so getting the maximum amount of movement from any swinging going on.

I have bits cut out and ready to go – I'll be reporting back in the tomorrow.

Here's one that didn't work.

Well, it did work but it is far too bulky.

In this mechanism, the pendulum and the bell crank are a single piece. To get a reasonable amount of vertical movement the side arm needed to be long making the project over wide. To minimise the width I moved the pendulum right over to the side which also meant that the whole thing was unstable. Pah.