In sticking with the theme of repairing old chronographs, I picked up another Pierce Navigator a few months back from eBay in non-working order. This chronograph is a little bit different from the others that I have repaired in that it’s a single button chronograph. A single button chronograph is a closer relative to the stop watch since only one button is utilized for the start, stop, and resetting action.
The watch arrived exactly as described on eBay, which is to say it was lacking a crown and the chronograph pusher, but since I had a few other Pierces lying around I was able to source a replacement crown and stem in order to give it a wind. The watch started ticking but was unable to keep time. Regardless, I placed it on the timegrapher to get an idea how bad the damage was.
Removing the caseback revealed a highly tarnished and dirty movement, but one what had no obvious broken or missing parts.
I removed the movement from the case and placed it in a movement holder for service. Here I noticed a finger print on the chronograph engaging spring. Finger prints on the movement are usually an ominous sign.
I’m pretty quick when it comes to breaking down Pierce chronographs and this one was no exception. The chronograph movement came away quickly.
The chronograph staff should have a rubber clutch at its base but since these watches are over sixty years old most have had the clutches disintegrate over the years. This watch clearly suffered that fate as well; the rubber clutch plate has been replaced at some point with a brass sleeve that may have worked just as well.
With the chronograph works broken down I moved onto the wheel train which was dirty but otherwise in good repair.
A close inspection of the disassembled movement revealed more repair work. Apparently there was an issue with the balance or hairspring as this hairspring has been re-studded and the watchmaker didn’t cut down the stud pin. A short hairspring would cause the watch to run fast which this watch seems to be doing.
After sending the parts off to the cleaning machine I turned my attention to the watch case and noted an issue where the chronograph pusher should go. The pusher had broken off in the case.
Using a small metric drill bit and a pin vice, I drilled out the pusher hole. This is probably the only time I’ve been thankful that the Pierce chronograph pushers are made of brass and not steel.
Next I set my attention to fabricating a new clutch for the chronograph staff. Using a narrow rod of nylon, I turned a new clutch plate that is 2.05mm in diameter and 0.45mm thick. The center was drilled out using one of the metric drill bits.
Assembly of the watch began with a new-old stock mainspring I purchased from eBay and proceeded quickly.
Unfortunately the watch was still running quite quickly so before I installed the chronograph works I gave the watch a full wind and let it run overnight to distribute the oil. This would give me a proper idea of how far off the norm the timekeeping ability was.
The next day I discovered that the mainspring had failed. Let this be a lesson to all to avoid new-old stock mainsprings whenever possible.
A proper replacement mainspring was ordered from Cousins and the movement disassembled. When the new spring arrived I reassembled the watch movement and replaced the balance and hairspring which resolved the issue of it running fast.
I then rebuilt the chronograph works and awaited the return of the case from RePlateIt.
RePlateIt had done a fantastic job replating the yellow gold watch case. They also plated a new chronograph pusher which I then installed in the case with a small application of Molykote grease. I used Molykote on the chronograph pusher and also the adjusting screws of the chronograph connecting lever as it’s extremely slippery stuff and works well in places where there is a a lot of friction and pressure.
Once back in the case it was time to reinstall the dial. The dial has held up really well on this watch but I did notice under the microscope that at some point the crystal must have been installed with glue. A bit of pegwood removed the glue residue which was found all the way around the dial edge.
A new crystal and new set of hands completed the repair.
This is by far the best looking Pierce I’ve worked on. I originally intended to resell this one but gosh, it’s hard to part with such a gorgeous watch!