This project is a candleholder with three gears and parallel action arms which move the candles up and down at different rates.It is made from aluminum plate and uses tea lights or small floating candles. The design and the variable gearing make it a playful device.
Step 1: Marking and cutting the Gears
I make gears basically by drilling holes in a circle, and then cutting away excess material so that the holes become the "valleys" between teeth. The diameter of the circle that passes through the center of each tooth (the Pitch Circle), is calculated by the formula shown below.
Also note the additional holes marked "#25". These are mounting holes for the connecting rods that join to the parallel arms. They need to be drilled with a #25 drill bit, and then tapped with a 10-24 tap to accept the shoulder bolts that act as pivots for the connecting arms.
Step 2: Cutting the Chassis Plates
The front and back plates of the chassis are cut from 1/4" aluminum plate. Use the chart below to mark out the back plate, then use the back plate to mark up the front plate (remember the front plate does not have holes for the gears, so it can be much smaller and simpler.
Step 3: The feet and knob
The feet are cut from 7/8" diameter aluminum rod. I cut slots in the rods to fit the front and back plates of the chassis into. During final assembly, you will epoxy the feet in place.
The knob can be any shape, but I made it in a similar shape as the gears. It needs a center hole, 1/4" dia., and a 1/4" shaft collar joined to the knob with a tension pin (see photos).