Just finished the COA on a commissioned buy for a client. The watch was gummed up and would not even try to run when it came in. After the COA it runs with a beat error of 3ms in all positions and runs at 17976 to 17978 in all positions... does not deviate more than plus or minus 1 beat.
I've heard tell that these watches predate the requirement to be marked for position adjustments, but the numbers tell me this is a 5 position watch if not 6 positions.
Now, I have no idea how to speed it up with no mean time screws... The hair spring is conveniently pinned to the stud... should I slip the hair spring a couple millimeters? Or is there another method short of shaving the balance weights I have not learned yet.
The regulator was biased toward fast when it came in... I can get it to 17999 if I run the regulator all the way to fast, but would rather make the permanent adjustment... just want to make sure I'm not missing something before I go unpinning the hairspring and putting myself in harms way.
Posts: 2032 | Location: San Diego, California in the USA | Registered: August 30, 2012
Thanks Buster... it looked a bit like the JBoss football... but I somehow knew it was neither Keystone nor Crescent Watch Case Co.
Chris, Thank you for bringing me back to the basics. I'll demag it and break out my 20X to look for balance weights when I get back to my bench tonight.
As for the amplitude, this thing has wonderful free balance assembly checks in all positions and when assembled, runs with a full amplitude of 270 in all positions. There is no visual or audible change in her cadence or amplitude as I roll her through the positions.
Posts: 2032 | Location: San Diego, California in the USA | Registered: August 30, 2012
Also check to see that the regulator pins are not spread too far apart. If the gap is even only slightly too wide you can have a substantial slowing of the timing.
Posts: 1078 | Location: Ticonderoga, New York USA | Registered: March 01, 2008
I'm fascinated that de-maging the watch gained me 2 beats per hour. The balance weights were unfettered, no washers, no undercuts.
Dave called to recommend undercutting the balance weights, but I really wanted to avoid this if I could.
As it turned out, unpinning the hair spring and slipping it a four millimeters over shot my mark from being 20 beats slow to 30 beats fast... it took me another three attempts to find the exact position to pin the hair spring to hit my mark at 18000.
The trick was to take a new full length spring pin from my meager stock... chuck the smallest one I had up in the lathe... Then I used Mommas nail file board with the finest grit she has... and turned the pin down small enough for the hairspring stud hole.
Working with a full length un-cut pin was much easier than feeding the original cut pin in and out as I narrowed down the mark for the final position.
As expected, moving the hairspring did affect beat error moving it from 3ms to about 9ms... but I was able to correct this by rotating the hairspring collet in the opposite direction from the hairspring stud adjustment...
I should be done with the case and crystal work tomorrow.. pictures to follow.
Posts: 2032 | Location: San Diego, California in the USA | Registered: August 30, 2012