Sometimes, when creating a new paper animation, I start with the character and fit the mech to it. With this diver model, I’m working on the mechanism first.


In the model, there will be a body swooping back and forth and two legs which will be moving up and down at a faster rate. I’m starting with the leg mechanism. These two tubes will be joined together to make the vertical shaft onto which the diver is attached. The yellow sliders will be used to drive the legs.


I’m concerned that the two sliders might catch against each other jamming up the mechanism. They only need to move up and down by about 10mm so I changed the design so that the yellow slider tubes are longer than half the length of the blue tube. No chance of catching now!

I fitted the parts together and added an axle tube at the bottom end…

I then added a two-lobed cam with 10mm lift to each side of the axle. The orange cam follower then touches the cam lifting the yellow tube on each side. The coin at the top of the yellow slider helps push the slider back down.

Next step: There a few changes I’ll probably make to this design, for example, I’ll make the yellow sliders even longer and probably change the way the cams are attached. I’m also going to change the cam profile so that it lifts slowly and drops quickly. I might also try a three lobed cam for a faster kicking action. After that, I’ll add the crank and the box. Looking promising!