This is a just a fun little desk toy representation of the curve on which a square can roll smoothly, inspired by Vsauce's explanation of it in his video on brachistochrones (https://www.youtube.com/watch?v=skvnj67YGmw) and Devin Montes from Make Anything's use of 3D printing to represent the tautochrone (https://www.youtube.com/watch?v=dIip9yXK8-M) (both of which are really awesome and you should check them out!). Traditionally, you don't think of square wheels as being capable of turning smoothly and traveling only in a horizontal line. Similarly, we don't think of a non-flat road as being able to be driven across smoothly and traveling only in a horizontal line. The very specific geometries utilized in this toy, however, make both things possible. This toy also allows you to actually see and feel the squares turning, making it far more fascinating and a more visually interesting demonstration of the principle than just looking at an animation. A fun and easy print, this desk toy will certainly make people stop and look twice!
While this is definitely able and ready to be printed right now (and I encourage you to do so), it is still a work in progress and you can expect files to change somewhat in the near future. I have not actually got around to printing this on my own printer just yet, so there may be some small tolerance adjustments that need to be made that I won't know about until I print it. If you do print it, please share and please send me feedback so I can make the changes you think are needed! I have also attached the multi-body Solidworks part file that I designed everything in (as well as a STEP file for anyone without Solidworks), so please feel free to make changes and share your improvements on my design. Just let me know if you have any questions or problems.
Just print the specified amount of each of the pieces!
Base - x1
Connector - x2
Crank - x1
End Gear - x2
Handle - x1 (technically optional, although I highly recommend you print it because it allows you to turn the shaft without having to turn your grip)
Middle Gear -x1
Pin - x2
Square - x2
Wall - x2
Once you've printed all the parts out you should be ready to assembly them (although you may have to do some sanding first if your tolerances are too tight). Assembly is fairly straightforward and you should be able to figure out what goes where based on the pictures, but just in case it isn't, here's a quick guide to make your life easier!
- Put the two Pin pieces and the Shaft through the holes of one of the Connectors.
- Slide one Square piece onto each of the Pins until it is flat against the Connector (you may want to use some glue to secure the Squares onto the Pins if your tolerances are too loose).
- Slide the second Connector onto the two Pins until it is against the Squares.
- Slide the two Walls onto the Pins and Shaft on either end until they are flat against the Connectors on opposite sides.
- Insert the pegs on the Walls into the holes in the Base piece.
- Slide the Middle Gear onto the straight end of the Shaft on the outside of the Wall.
- Slide an End Gear onto the long ends of each of the Pins on the outside of the Wall (again, you may want to use some glue here if these are loose), ensuring that the teeth line up with the Middle Gear and that the Squares sit properly.
- Slide the Handle onto the opposite end of the Shaft.
- Start turning and enjoy the satisfaction.