This pendulum arm was made for my AP Physics C class in order to experiment with the effects of mass and pendulum length on the chaotic behavior of a double pendulum system.

Assembly:

1. Print two copies of top and bottom pendulum halves, at least four snap pins (printing extras are recommended as they are fragile), a pendulum connector, and three inner bearing pieces (printing extras is recommended). 50% to 100% infill recommend, 15% infill normally leads to cracks in the bearing holes.

2. Take the top and bottom halves of the pendulum arm and line up the holes for the desired length. Put pins into holes that you think will make the pendulum the sturdiest. Repeat for second pendulum.

3. Place 608zz bearings (22mm outer radius, 8mm bore, 7mm height) into both holes of the bottom pendulum arm. Place one bearing into the top of the top pendulum arm and a pendulum connector piece into the bottom hole.

4. Press inner bearing pieces into bearings. To connect the pendulums take a m4 rod and screw it through the pendulum connector and a inner bearing piece of the bottom pendulum. Use additional spacers if pendulum collides with itself

5. To add weights screw a m4 rod through the bottom bearing on the bottom pendulum. This allows weights to be added to the top pendulum (the rod to connect the pendulums doubles as a weight holder) and the bottom pendulum. Wing nuts seem to be the best to secure weights like washers.