Last modified: 2025-01-18 22:24:19
< 2025-01-16 2025-01-19 >This page was on HN today: https://genuineideas.com/ArticlesIndex/phase.html
Lots of discussion of historical methods of moon phase display. They mainly take beef with the fact that the "circle occluded by circle" method always has a crescent across the moon at half-moon, when in reality it should show a straight line, and then they present various methods of fixing it. They come up with a version based on sliding segments that could maybe work in a wristwatch. For my clock I think a rotating sphere would be fine, black on one side and white on the other. That's if I decided to add a moon phase display, of course.
More important to get it running for a year at all first.
My new 3mm micro bearings have arrived, I'll try them out. First impression is they look much higher quality. Also a lot less play in them, tighter fit on the shaft, no wobble in the races, good.
Doesn't spin super freely, I need to soak them in IPA to thin the oil I think.
After only a few minutes' soaking, I gave it another go. Much better already. I span the escape wheel in the old bearings and it span for 55 seconds before stopping, in the new ones 52 seconds.
I tried again and got 43 seconds in the new bearings and 35 seconds on the old ones. I think I'd need a more repeatable way of starting it at a constant speed to decide which is better. But I think the new bearings aren't obviously better or worse than the old ones, maybe a bit more soaking in the alcohol will do it. (But then maybe a bit more soaking in alcohol would have fixed up the old ones as well?).
I could really do with some sort of pivot friction testing rig.
After letting them soak for a few more hours, I'm getting ~50 seconds with the old, 5mm, bearings, and ~30 seconds with the new 3mm ones.
I think give up on the bearings for now.
I've bent up a new balance spring that is much longer, it now ticks with about a 5.8 second period, with only 2 M12 bolts for balance weights (was previously 5.25 seconds with 4 bolts). So now I guess reassemble everything else and see how it works?
So far it's not working. Seems like the remontoire has gained a lot of friction or something, it can't put enough energy into the balance to even keep the clock running. And that's with the same remontoire weight as before. So not energy saving whatsoever.
OK, update: I adjusted the balance pivots a bit, now it is running, I've slid the remontoire weight inwards and it is still working, stable at about 170 deg. amplitude, which is maybe lower than I'd like. The balance spring is rubbing so fixing that would help. Period is about 5.75 seconds.
The remontoire is winding very strongly, I can probably reduce the drive weight. It's working with only 10x M20 nuts (down from 12).
So overall there is a power consumption reduction of about 25%! When you factor in the reduced drive weight and the increased period.
I've stopped mucking about with it now, kicked it off at 22:23, hopefully tomorrow I can have a look at the "historical data".
< 2025-01-16 2025-01-19 >