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Discussion Starter #1
I just got a beautiful sushi roll 6119-7163 from 1970 to restore for a customer. STUNNING blue dial, by the way. The watch is seemingly all original save for the stem.

The indicator would not turn around the dial despite the wheel (gear) and spring being in place and correct in size. After a bit of frustration, I double-checked the stem part number, pulled one out of my inventory and discovered the very slight difference. Evidently, someone, at some point, replaced the stem, crown, wheel(gear) and spring but used the wrong stem.

Rather than try to show this in photos and in need of some practice on my CAD program, I made this drawing to show my customer how much 0.30mm really is...



The incorrect stem's center section being 0.30mm too long does not allow the wheel to contact the gear track of the indicator.

The gear on the stem is held by the spring so it contacts the indicator track when the stem is in it's "0" position. When the stem is pulled out to its "1" position for setting the hands, the gear is pulled away from the indicator track so it will not change its position while the time is being set.

The reason for this somewhat elaborate detail is to prevent the gear from damaging the plastic track of the indicator when the stem is inserted to the movement. The spring allows the gear to slide away from the track during insertion, then snap into its correct position as the stem hits home.
 

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It is all in the details when working on watches, a difference of 0.3 mm is very hard to see and find out.
You seem to have very good eyes.
 

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Thats awesome. any idea what the stem used was from?
 

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This post clearly illustrates that watches are perfect examples of high end manufacturing and precision engineering, and why so many large watch making companies have expanded into so many other precision manufacturing businesses (especially electronics related ones).
 

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Discussion Starter #7
Technoman said:
Thats awesome. any idea what the stem used was from?
I haven't had time to track down the correct watch for the incorrect stem but I am pretty sure it is one that has a slightly larger diameter dial and indicator ring.
 

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Craftsman
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Size is relevant, 0.3 mm is 300 microns, at work we regularly work to 5 microns. I made some case springs for Bellmatics, and had to increase the circumference by 30 microns (0.03 mm) to get e perfect fit.
Size is everthing when you are an instrument maker by trade
 

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Discussion Starter #10
daveeb said:
Size is relevant, 0.3 mm is 300 microns, at work we regularly work to 5 microns. I made some case springs for Bellmatics, and had to increase the circumference by 30 microns (0.03 mm) to get e perfect fit.
Size is everthing when you are an instrument maker by trade
My point exactly. The 0.03mm to most is insignificant but it is the difference between the gear hitting home or floating in space.
 
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