Rowboat Toy
A mechanical rowboat toy that moves using a Scott Russell linkage
In my CAD course, my team and I made a rowboat toy mechanism using a Scott Russell linkage. First, we designed a 2D version that'd be laser cut, then we modified it into a 3D version that was 3D printed.
After some rough sketches and some confusing tolerancing, we had our 2D model designed and ready to cut. The boat would be split into three pieces (a solid back, a hollow middle shell, and a front with a cutout).
The linkage would operate through a post and the oar, with the head of the oar following the cutout. Moving the oar would also bend the arms, completing the rowing motion. The individual pieces were fastened together using dowels and wood glue.
We ran into trouble adapting the boat to 3D, but we found a way forwards by shifting the pivot point from the boat's side to the internal post. It also helped moving the post to the front and making it stationary.
(we lost the plot on the Scott Russell linkage a bit, but that's ok).
As for some fun design errors/challenges:
On the 2D design, the person was supposed to sit on top of the boat, but the small surface area didn't give the glue enough space to hold it, so we just ended up gluing it to the back.
On the 3D design, the internal post was initially too tall to rotate the arms and oar. We tried sanding and cutting down the post, but it started taking so long that we just ended up reprinting everything (besides the oars for some reason).