Adjustable Pendulum Arm

thingiverse

This double pendulum system was designed for my AP Physics C class to explore the effects of mass and pendulum length on chaotic behavior. Assembly: 1) Print two copies of top and bottom pendulum halves, at least four snap pins (printing extras is recommended as they are fragile), a pendulum connector, and three inner bearing pieces (printing extras is recommended). A 50% to 100% infill recommendation is made, while 15% infill normally leads to cracks in the bearing holes. 2) Align the top and bottom halves of the pendulum arm by lining up the holes for the desired length. Insert pins into holes that will make the pendulum the sturdiest. Repeat this process for the second pendulum. 3) Place 608zz bearings (22mm outer radius, 8mm bore, 7mm height) into both holes of the bottom pendulum arm. Insert 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, screw an m4 rod through the pendulum connector and an inner bearing piece of the bottom pendulum. Additional spacers may be needed if the pendulum collides with itself. 5) To add weights, screw an m4 rod through the bottom bearing on the bottom pendulum. This allows weights to be added to both the top and bottom pendulums. Wing nuts are the best option for securing weights like washers.