Chuck, My dad has one of the original tuning fork Accutron. I know he stopped wearing it a while back, but I am not sure why. I will ask him if he still has it and if it works and in case he does, I would like to go back to you for more information in order to make it work again, if that's OK.
Thanks in advance, Didier > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris > Sent: Monday, December 03, 2007 6:51 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Watches > > Hi Tom, > > Yep, there was a weak point there, but not for the reasons > you might imagine. The big 300 tooth wheel was a ratchet > wheel that was driven by a pair of sapphire pawls that were > attached the tuning fork by a thin springy wire. The 300 > tooth wheel directly drove the second hand of the watch. > That is why the watch had that velvet smooth second hand. If > the watchmaker forced the second hand to rotate, it would > bend the springy pieces of wire (not wire actually), and that > was that. > > It was difficult adjusting the phase of the two ratchet pawls > relative to the teeth on the wheel. One pawl had to be half > way between a root and a crest when the motive pawl ligned up > with a crest. A 20-30x microscope was necessary.... that and > a very steady hand. > > Electrically the biggest failure item was the tuning fork > coils themselves. The coils were wound with wire that was > around #48 AWG. It would break, or corrode at the solder > joint, and the watch would stop. Rewinding the coils is a > doable task if you can get the wire, and you know how to deal with it. > > Now days, the 1.35V mercury cells that the Accutron used are > no longer available, and the 1.5V silver oxide cells > overdrive the tuning fork, causing lots of noise, and motion > problems. Changing a resistor, and adjusting the phase of > the pawls will usually allow the use of politically correct cells. > > -Chuck Harris > > Thomas A. Frank wrote: > >> Real tuning form Accutrons are collectibles now, and it is not > >> unheard of for an unscrupulous watchmaker to steal the > movement out > >> of one, and replace it with a cheap quartz movement, all > in the name > >> of doing the watch's owner a favor. > > > > Not just unscrupulous watchmakers, that's what happens if you send > > your watch back to Bulova for repair! > > > > If you know enough to include a note saying do not replace, they > > return it untouched, as they no longer service the tuning fork > > movements (I imagine they would put in a battery and new > o-rings for > > the case, but anyone can do that, so why risk a possible error?). > > > > There are now folks who specialize in repairing these nifty > pieces of > > technological ephemera. > > > > I understand the weak point in the design is the 300 tooth escape > > wheel which rides the tuning fork. Fragile teeth. > > > > Tom Frank > > > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, > go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.