Last modified: 2023-12-10 13:33:39
< 2023-12-08 2023-12-10 >I'm trying to free up the balance wheel on the plastic 1x escapement. It's not clear whether the problem is with the pivots or with the hairspring rubbing on itself.
Well the hairspring is very obviously problematic. I will try to change to holding it in the housing with a pin instead of a screw, because tightening the screw twists the spring.
Gould writes in "The Marine Chronometer: Its History and Development" about Nuremberg Eggs, which are an early type of spring-driven watch with verge escapement. Maybe I should forget the captive lever escapement model for now until I can reproduce a Nuremberg Egg-level movement.
But first I will try to get this plastic model to tick more convincingly.
With the balance spring removed, it spins nice and freely in each pivot individually. I can't check both at the same time without removing the impulse pin.
I've put a new hairspring on, because the old one was too crooked:
Obviously the pin is longer than it needs to be, but this looks a lot more convincing, and it looks like it swings back and forth for longer before it stops.
With the pallet fork installed it is obvious that the slot is too short. The impulse pin hits the bottom of the slot before it passes the centre position. So of course it will never tick. Remedy: try to make the slot longer with a knife, failing that print another one.
Also it rubs on the top of the slot at a point where the receiving pallet pin is already banked on the escape wheel, which will also prevent it from ticking. Remedy: maybe try to bend the pallet fork? At least review the range of motion in reality compared to CAD.
Also the escape wheel is nearly completely separated from its pinion. Remedy: drip a bit of superglue on it?
The impulse pin looks to be rubbing against the slot on both the upper and lower side, which suggests the lever isn't moving through a large enough angle (the pins hit the escape wheel too early) or the slot is too narrow.
This pic shows the limit of the lever motion on the upper side:
Observe that the impulse pin is touching the slot, and the receiving pallet pin is touching the escape wheel. Now let's compare to CAD...
Well I compared to CAD and the comparison wasn't sufficiently high-resolution to notice the difference.
20.32: the beech clock is making an awful racket. Maybe the 12v transformer does more harm than good, tempting to go back to 6.3v. I turned it off and on again and it is quiet again, not sure what is up there. If it happens again I will try to rectify it.
20.36: It happened again! But I noticed the lights dimmed momentarily at the same time as it started humming. Which was caused by which?
I've added some documentation in stepper-motor-clock.md.
Plan to look more at the 3d-printed 1x escapement. Probably print a new pallet fork with more clearance on the slot. And then maybe think about making a verge watch.
< 2023-12-08 2023-12-10 >