Showing posts with label marathon. Show all posts
Showing posts with label marathon. Show all posts

Thursday, November 18, 2010

Fixed my Military Navigator Watch

Made by the Swiss Gallet Watch Co for Marathon, the 6 prototypes were called "Desert Storm" on the dials. I wonder why? This one is a 1990, steel-bodied, signed "Marathon".

Have a look:

1990 Marathon Navigator

The Harley-Ronda 373 movement was ticking - but only moving the seconds hand back and forth, even with a fresh battery. A spare movement from my parts bin fixed that problem. The bi-directional bezel was sloppy and not clicking as it should. The internal spring was distorted and had a segment missing. It measured as 0.015" thick so I stole a guitar string from my studio and made a 0.016" replacement which was a little harder to refit the bezel but, once on, a much nicer fit and feel.

Eagle-eyed folks will notice the considerable bending up of the hands near the posts. I could have swapped the taller posts over from the dead movement but anyone who has attempted this on a Harley-Ronda 373 will understand exactly why I didn't. This watch was already built from a pile of parts and it's my current beater, not for sale, so it's really no sin to do things like that.


Best regards, xpatUSA

Friday, August 14, 2009

Removing/Replacing a Gallet snap-back

These military backs are really hard to remove. If you do manage to struggle one off, putting it back on ain't that easy, either. I'm sure that there are proper tools out there that will do the job perfectly but, if you're brave, here's how I do it.

lube
First, using a small screwdriver or a plastic cocktail stick, put a few drops of your favorite penetrating oil around the join and leave it for a few hours.

chisel
This is the business end of my Dad's old mortising chisel. The blade section is about 7/16" square and the tool is about 18" long. The end will need a quite shallow bevel, less than that of a properly sharpened chisel.

mounted in vise
Place the watch in a vise, which must have soft alloy protectors on the jaws or, better yet, medium hard plastic ones. Tighten the vise just enough to prevent the lugs opposite the chisel from riding up the jaw under pressure.

mounted in vise
In this view you can see that the back does have a slight chamfer that the chisel blade can contact. Sometimes, the gasket is not fully compressed and there's a small gap to allow the blade to insert itself further.

chisel in operating position
Ignore the photo above, I don't push on the lug any more. Instead, I rest the chisel on the vice jaw, making quite sure that it is not going to bear on the strap bar. Push the chisel firmly forward into the chamfer on the underside of the snap-back and lever the chisel handle downward. The back can fly off with a loud ping, so arrange that it can not land good side down (like toast) on your hard uneven concrete floor.

crown stem detent
If you need to remove the movement, push the little button while pulling on the crown

clamp
A woodworker's clamp can be used to refit the back to the watch.

press setup
Put a very thin coating of grease around the spigot on the body where the back fits. The PVC pipe connector fits over the bezel but does not press on the crystal. The scrap plastic plug presses on the inner part of the back - the theory being that the back might flex enough to open out it's edges a little.

press setup detail
Tighten the clamp slowly, all the while making sure that parts stay as parallel as possible. I find that pressure builds up and up - and then the back just slips on. Make sure it is even all the way around. Move the plug over and re-clamp if one side of the back is not all the way on.

Y'all be careful now and don't force anything!

Best regards,
xpatUSA