[Robotgroup] Bead Chain Sprockets

[vkonradi]

Once upon a time, neeting a much-larger-than-stock bicycle front sprocket (for a much-faster-than-normal bicycle, naturally), I made a quite acceptable chainwheel from flat aluminum sheet stock.  Basically just plotted a circle of points at radius N*pitch/2*Pi, where N is number of teeth, then carefully center punched and drilled them.

The one hole most important to place extremely accurately is actually the center hole, to avoid radial runout.  Best way to do this is to drill this hole first, then use it as the center as you plot out the circle.

After drilling, band saw a line through the center of the holes, leaving semicircle arcs.  That's all, you have a nice bicycle chainwheel.

I was accomodating a chain, which of course centers itself on the sprocket.  For a bead chain sprocket, add two plates on the sides to capture the chain and prevent it from sliding off the sides.

-Vadim