The bird anatomy pictures were really helpful in creating the new version. I created a box in Fusion360 and added the picture as a decal.
I then used that to trace out the two parts of the leg. Previously I’d modeled all the pins and holes but a bit of experimentation showed that I could have a simpler version and it would still move, so I did that for this version.
The rotating joints were added and the sliding joint was added. A rough foot was sketched and fixed to the lower leg using a rigid constraint. My problem came when I tested things out. I rotated the driving wheel and the backboard just span around. I found the solution via this Pluralsight video on Joints and As-Built Joints. You need to mark the base as “Ground” which pins it in place. The other interesting thing I learnt this week was the Motion Links this joins up items such as gears or screw threads. So the motion of one item drives another directly without needing to model the linking.
For the sliding joint to provide the desired motion requires some end stops to limit the motion. I’ll be using a brass pipe and brass rod for the legs and this joint. I can limit one end of the movement simply by blocking the end of the pipe, the other end I’ll need to create something like a piston where the inner portion is larger than the outer.
The foot will be made using some Sugru, I experimented with the “Create Form” option in Fusion 360 to create something bird-like. I’ll likely make the toes a bit longer so perhaps a wire former to give them support. Looking at reference material the Dodo has big black claws on the end of the toes and back of the foot. I’ll likely print these or possibly hand carve them.
For the glowing lava of the volcano, I’m planning to use a small DC motor running as a generator to flash some LEDs. I hope to have these flicker or pulsate rather than be rhythmical. The most promising circuit option I’ve seen so far uses a candle flickering LED to drive a transistor to control the main LEDs.
To drive the generator I’m thinking that the input hand crank will need to be geared up so that the generator spins at a higher speed.
I used my new found knowledge of making gears and motion links to animate that in Fusion 360.