Benrus sky chief 72c

[dennis]

18 minutes ago, FLwatchguy73 said:

unless the hairspring stud is on an adjustable arm, you'll have to move the hairspring collet to tighten up that beat error. That will likely also improve your amplitude. Excellent progress!

Thanks. Talking through and getting great advice goes a long way.

Will adjust the hs tomorrow. thanks again!

 

[Marc]

That's a big improvement. Like @FLwatchguy73 says, if you can reduce the beat error a bit you'll have cracked it. 

[FLwatchguy73]

Just to clarify for the folks who may not know about amplitude, i.e., do I have enough, too much, etc,  I'm posting a link to an article about balance amplitude. It's pretty informative, here is the key quote from that article in regards to our discussion here:

"An amplitude that’s too low causes problems with timekeeping. Every time the watch changes position (especially a vertical position because of the higher friction of the balance staff), the amplitude drops. If it’s already low, to begin with, the amplitude will drop so low that it’ll affect the rate of the watch.

An amplitude that’s too high can cause knocking or banking. That means that the impulse pin comes around entirely and hits the back of the pallet fork.The amplitude of a modern watch should be between 275 and 315 degrees. In a vintage watch, an amplitude between 250 and 300 degrees is fine."

Very useful information.

Original article....

https://wahawatches.com/watch-talk-whats-the-amplitude-of-a-watch/

 

[FLwatchguy73]

Just out of curiosity, I recorded one of my pocket watches in SLO mo just to see if I could estimate its amplitude. Looks like it's running about 270 degrees. Not too shabby for a 107 year old watch!