Further experiments on the Bird Box project. This time, a crank with a big throw (70mm between the extremes) driving a higher volume bellows. You can click on the picture to see a quick Instagram video clip with sound of the first draft.
I had fun folding up the bellows. Starting with a modified version of the bellows from the squeeze box project I’ve made an Instagram video of me folding up the bellows at super speed.
Everything fits together quite nicely, the box will need to be slightly wider and deeper as the top plate of the bellows catches on the inner walls but apart from that, it is looking good.
My next plan was to try changing the pitch as the bellows move. Fitting a plunger into the tube of the pipe should let me change the pitch of the pipe in the same way that a Swanee whistle works. A loose fitting plunger seems to work well and over comes the problems I had had before of tight tolerances. My initial plan had been to use the main crank to move the plunger in and out via a bell crank. After a bit of thought though, I think a cam might be a better idea.
If I can add enough weight to the plunger so that it drops under gravity into the pipe tube I should be able to make it move up and down with a cam. As the plunger moves the pitch of the note changes. Hopefully I will be able to simulate some birdsong.