It’s best to think of this post like an apologetic hint to a certain friend that may or may not be expecting a certain “project” to be done in 14 days time…that I may or may not be able to realistically finish. But, say I was still pushing to complete said “project”, I thought I’d share some of my ambiguous progress.

The Geneva Stop

I decided pretty early that my “project” would involve some sort of mechanical movement…a decision that perhaps doomed it’s feasibility right from day one.

I had 3 front-runner ideas for my “project”, but in the end, I finally settled on the one that would require what is commonly called a Geneva Stop. Invented in Geneva (of all places!), this ingenious mechanism allows the drive wheel to continuously rotate, while the driven wheel rotates intermittently, making it ideal for things like mechanical watches and old-school movie projectors.

For example, in its most common 4-slot-1-pin form, the driven wheel rotates 90 degrees for every full rotation of the drive wheel. Similarly, for X slots (still with a single drive pin), the driven wheel rotates (360/X) degrees for every full rotation of the drive wheel.

What could I be using this for? What could I be using this for, indeed…

How Many Geneva Stops Does it Take…

My initial test was just to see how well the intermittent pin-drive worked. It had a single pin, but without any backspin blocking. It worked.

The second iteration was intended to test the rotation locking disc, which is the raised disc in the center with half-moon cutouts. The idea is that, when the intermittent wheel is being driven by the pin, the spokes can freely move through the concave portion. But when the intermittent wheel is not being driven, the convex portion holds the wheel in place, preventing backspinning. It “worked”…but due to some miscalculations, not well.

This iteration was also intended to test a dual-pin drive such that the intermittent wheel will rotate twice for every full rotation of the drive wheel. In the third iteration, this second drive pin would allow for two intermittent wheels to be simultaneously driven. It also “worked”…certainly better than iteration #2, but with more moving parts, the system was that much more finicky.

Or rather…Geneva Stopped

While one of the many reasons to go with the geneva stop was because I don’t have the patience or the skill to make actual wooden gears, it has become quickly apparent that I also do not have the patience or the skill to make geneva stops.

So unfortunately, this project has been delayed largely due to the fact that I can’t get a smooth running mechanism.

But I’m still fascinated…and not giving up.

Demonstration of “working” experiments: