As anyone who has invested a little time perusing this blog will know, I have a hard time passing up an affordable chronograph that is in need of some TLC and so it is that I found myself with another Pierce Navigator in less than pristine condition.
This Navigator is another large dial chronograph by Pierce SA from the late 1940’s or early 1950’s. I found it on eBay and offered the owner a reasonable sum with the intention of using the watch for parts but instead went straight for a full restoration.
The watch was purchased in non-working order as usual but upon removing the caseback I discovered the reason for the watch’s failure was simply a loose case screw in the works.
I removed the movement from the case and placed it in a movement holder for inspection. With the dial removed I could see that the movement was relatively clean with little rust damage.
The front side of the movement was a little worse for wear. The chronograph staff, pinion, and intermediate wheels were all missing and would need replacement. I also noted that the actuating push piece spring (which resets the chronograph pusher) was broken.
I rummaged up a replacement stem in order to wind the mainspring and placed the movement on the timegrapher. The reading was terrible.
The amplitude was acceptable considering the watch needed a cleaning and lubrication but the beat error would need to be corrected and the fact that the watch was gaining four minutes a day could be a real problem.
I broke the movement down quickly and separated the parts for cleaning.
Following a solvent bath and two rinses the parts were dried with a heat gun and laid out upon the workbench for inspection.
The base movement assembly is pretty straightforward as usual. The keyless works (winding mechanism) has the most bits and can take a while. The gear train is pretty simple.
A replacement chronograph staff, pinion, and intermediate wheel were taken from my stock of parts in order to rebuild the chronograph works. The staff needed a new clutch which I fabricated on the lathe from a rod of nylon.
I reduced the width of the rod to 2.1mm then severed the end with a graver; this would serve as the replacement clutch plate. Since the plate needs to be almost perfectly flat, I secured the severed bit to a brass plate with warm shellack then flattened the disk with a small file.
When the desired thickness was achieved, the plate was removed and a hole drilled for the chronograph staff.
With the clutch plate complete I was ready to rebuild the chronograph works.
With the movement ticking away and the chronograph more or less set, I moved on to the aesthetics of the piece.
Since the hands were greatly oxidized, I polished them up with the Dremel tool. Next I mixed up some luminous compound to fill the hands. The dial is quite aged so a bit of pigment was added to the luminous compound to create a faux patina that is a little less jarring than bright white.
During the service I discovered that the movement ran fast and the timekeeping ability varied greatly based on the position tested (dial up, dial down, crown up, etc.). The culprit turned out to be an unbalanced balance wheel.
I confirmed this using a poising tool. The tool is set dead level and the balance wheel placed on the jeweled jaws. A puff of air from a bellows will set the wheel spinning. If it stops in the same place every time then you know the wheel is unbalanced.
I marked the side of the balance that was light and replaced the nearest screw with a heavier one from a scrapped balance wheel. The wheel was then retested on the poising tool before I reinstalled it in the movement. The result was much improved.
I must say I am quite pleased with the end result of this restoration project. This watch surely has a lot of history behind it and now probably has a bit more in front as well.