Spezialentwurf für Kurbelantrieb

[Piet Paardekam]

Building my new 20 key portable organ I had to solve a design problem first. I wanted to carry the case in front of me and to turn the crank on the right side of the organ. So any way I had to place the crankshaft 90 degrees turned in relation to the bellows. Also I had to place the command mechanism (Steuerungskasten) 90 degrees, but this is already done in the Beijertje and can be done by making this box as short as possible. The difference with the Beijertje was that my bellows have double blades, as the Höffle has it. In fact a "Höffle" with a turned crank.

So how to turn the crankshaft 90 degrees?

I could have chosen for the use of two 90-degree plastic or even metal gears in the crankshaft. But it is a quite complex thing to realise in a solid way as the gears have to stand the force of the turning wheel. Also the use of gears will take some extra energy.
It ended in a simple solution as you can see on the pictures below.
Some explanation:
- ball bearings on the crankshaft are not necessary, but it runs very smoothly and is easy to make
- the bearings on the cranktaps are made of synthetic material that is used to make kitchen table tops ( Anrichtetisch). Two halves (split using a jigsaw), kept together with two M5 bolts and with cutted thread for the two M6 pumping rods
- the handles on the two bellows are placed close to each other so the distance between the rods matches the distance of the two tap bearings on the crankshaft
- the parts are kept together in a temporary case during the building process. When everything is ready I will make the final case so it fits exactly in the smallest (and lightest) possible case.