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Comment by hammock | Hacker News Reader

Would be cool to build one of these in real life! Doesn't seem that hard to build, perhaps hard to calibrate though.

I don't see how a real life one could be made to look exactly the same (but I could be missing something).

The seems to have something that stops the end of it moving on until enough tension has built up to side underneath it. That much is fair enough. But then that same thing stopping the end would also prevent the same satisfying wiggle when it gets to the next position because it overshoots immediately.

The only thing I can think of is that the restraining pins move in and out is the clock have at just the right time but that would be quite a fiddly implementation and probably affect the visuals

You could get close by having the restraining pins hold the tip at 5N + 1 seconds instead of at 5N seconds

You’d need a mechanism at each 5 minute mark that grabbed the hand and released it at the appropriate time, then you could make the hands a s Wobbly as you want

A physical implementation could use magnets to hold to the specific spots. Once enough torque is built on trying to move the hand, it would snap out of place and would then find the next magnet and 'hold' onto that spot.

As an aside, I'm not sure that doing this for the hour hand is a "good" idea. The difference between 10:00 am and 11:00 am is significant and needing to check how much the bend is doesn't "feel" right.

(late edit thought) If we're getting to the "this is controlled by some other system that doesn't need to be purely mechanical", having an electromagnet on at the right spot that then toggles off at one 5m increment and on at the next so that there's only one magnet active at a time could reduce possible issues of having the wiggle/snap attach to the wrong magnet.

Using magnets would definitely make for a cooler look, but this effect can be done using nails of varying heights.

The thing that I wonder about (with nails) would be "what would happen if the the flexihand was able to wiggle past the peg when it moved from one peg to the next?" In that case, I believe, it would just be a regular clock style hand.

It's possible that I've got the wrong mental model for how that would work.

I think you'd put the nails at N+1 position, not N. (e.g. for the minute mark, you't put the nail at 6, 11, 16, etc. not 5, 10, 15). Then, the hand would press against the nail and progressively bend until it slipped past the nail entirely and jumped to the next 5 spot (and not yet be touching the next nail).

In exploring an idea on this a bit more... I found https://ferrolic.com which... is interesting. https://www.youtube.com/watch?v=5PFgVtzsXHM is another video on the idea.

See also: It Shall All Be Mine, Gregory Bae, 2016. "Atomic clocks that are magnetized to tick in place." https://www.gregorybae.com/It-Shall-All-Be-Mine

Currently on exhibit at Chicago MCA - https://visit.mcachicago.org/exhibitions/gregory-bae/

You can use a rubber second hand and put a nail at the 5 seconds, same effect.

That would probably prevent the wobble if the nails are not automatically retracted.

Without over complicating it, I wonder if you had a flexible second hand like a spring, that's just a bit too long, with pins on the 5 second hand, dots on the rest and decent motor to drive the shaft. As the shaft turns the spring builds up tension and eventually bends enough to jump past the pin.

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