Snap Linkage Bars

I have always liked linkage structures, simple to construct but fascinating to play with in math or mechanics. All children should have some experience with some linkages before entering the world of abstract geometry, I think. They provide numerous opportunities for children to wonder about the mathematics of geometry and movements. With 3D design, it is getting easier and more flexible. I have designed these pieces with K-12 teachers and students in mind. They are fairly easy to assemble or disassemble for open-ended explorations.

The center-to-center distance is 40mm. There are two types of links or bars and four types of pins, allowing for a variety of construction. Whenever you need to fix a point (e.g., with a nail of diameter about 3.5mm), you should use a hollow pin. If you need to connect three bars (layers), you need use a three-layer pin. Sometimes you may need a spacer to align the bars in space, too. There are numerous possibilities. Please print a bunch and give them to your kids. Yes, you could insert a regular pencil in the handle ring or a ballpoint pen (diameter < 3.5 mm) in a hollow pin and play with drawing!

Warning: As always, please take some time to educate young children not to put small parts in their mouth. Have fun making connections.

References:

1. https://en.wikipedia.org/wiki/Linkage_(mechanical
2. Cundy, H. M., & Rollett, A. P. (1961). Mathematical models (2nd ed.). London, UK: Oxford University Press.