Having completed a crank & cam mechanism for the upcoming Dodo model I'm now turning my attention to cam-only version In this mechanism I'll have two cams. One to move the body up and down, the other to controls the wings.
For the body I'm thinking that I'll use a circular cam with the centre offset to one side. (The thick black line on the picture) The heavy red line shows the design for the wings cam. The thin red spokes are evenly spaced approx 35 degrees apart. This will ensure that the as the cam turns the wing beats evenly. The interesting thing, though, is that as the cam shaft os offset to one side the cam teeth on the left are much bigger than those on the right.
I'd have completed this stage but I've spent much of the morning restoring my computer after a hard disk failure. Luckily everything was backed up. Thank Jobs for Time Machine!