Carefully swing the pendulum. The pendulum should move smoothly, not make noises, and not come apart or loosen at the joints. Look for any unstable joint or connection and any erratic movements during the swings. Check the c-clamps holding the top axle to ensure they stay tight. When you are satisfied that the movement of the double pendulum is smooth and that the apparatus is safe, loosen each hex nut and place one drop of the thread locker on the threaded rod where the hex nut will be located.
Hand tighten the hex nut to where it was located before adding the thread locker.
The thread locker will keep the hex nut from loosening on the threaded rod. As an alternative to using thread locker, you can use teflon pipe thread tape. Optimizing the design There are several ways to optimize the oscillation of your double pendulum. The double pendulum shown in our picture has sections cut from the lower wheels in order to reduce the mass at the lower axis of rotation. Use a hacksaw blade to trim pieces of the wheel.