Cycloid Banjo Peg
Well, here's my latest folly - a replica of the classic 1920s Grover 4:1 geared banjo peg.
Mine, on the left, has a 17:1 gear ratio:
My version of an exploded drawing:
The heart of the thing is its cycloid reduction mechanism. It has the equivalent of a ring gear, made with 18 equally spaced steel pins. Running in the center is an eccentric driving cam:
In the next photos, I hope you can see that the cam pushes the driving plate around, rolling its 17 notches along the pins, causing the plate to rotate exactly one notch for each revolution of the cam:
If you'd like to see a really cool flash animation of the cycloid principle,
This peg runs very smoothly and needs virtually no "drag" on the button to hold position well.
In fact, I think it would be the ideal tuner except for one thing - IT RUNS BACKWARDS!
Arrgh.......................