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Can someone help me with this Seiko


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This has been an ongoing project where I've gradually been collecting the parts to build a Seiko 6139 chronograph.

I wish I'd just bought a complete one now but that's another story.

So it was all going well right up to fitting the chronograph subdial hand.

Its in but very loose and just moves around. 

It is counting, but when resetting the chronograph it jumps out of position 

I need to stress the hands and dial are aftermarket parts 

I did notice that there is almost no pretusion of the chronograph hand stem out of the back of the dial 

It's pretty much flush so I'm wondering if something is missing from the movement that the hand pushes into 

Your thoughts gratefully received 

 

PXL_20241011_132311619.jpg

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9 minutes ago, AndyGSi said:

I could be that you've got the wrong sized tube on the hand or it could be that it's not setup correctly.

What size hand have you got and what tube length is on it?

 

To be honest I don't know but I'll have a look 

 

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There are different pivot lengths dependent on if it is a 6139A (part number 888 610) or a 6139B (part number 888 612). The centre chrono wheel for the A is a little bit shorter, so you may have put an A wheel in a B movement?

Edited by Pip
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10 minutes ago, Pip said:

There are different pivot lengths dependent on if it is a 6139A (part number 888 610) or a 6139B (part number 888 612). The centre chrono wheel for the A is a little bit shorter, so you may have put an A wheel in a B movement?

That wouldn't cause the hand to slip when resetting though would it.

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2 hours ago, AndyGSi said:

I expect from your description that it's more than likely a setup problem.

What manual have you used to build the movement?

I haven't built the movement.

 

30 minutes ago, AndyGSi said:

@nevenbekriev I've been working on the principal that it's the minute register.

The minute register is working fine. 

1 hour ago, nevenbekriev said:

OP, which hand are You talking about? The small minute register or central chrono hand?

As I said, the chronograph subdial hand 

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According to my own understanding of the matter, this watch has only one subdial and it is of the minute register. And, it has central chrono hand, which is not on subdial.

So, You problem is the chrono hand... The most probable reason is that the hand is not firmly seated on the shaft. This is a regular problem of such hands as the shock when resetting is huge  so the friction between the shaft and the hand's bush sometimes gives and the hand's position on the shaft changes. The hand must be pressed really tight. If the hole of the bush is enlarged, it is possible to shrink it. The best way to do it is in a lathe's collet. In the service centers they often don't reuse the hands, but rather replace them in order to avoid such problem. Another reason may be the bush is loose in the hand. And, of course, the movement may be out of order.

 

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16 minutes ago, nevenbekriev said:

You problem is the chrono hand... The most probable reason is that the hand is not firmly seated on the shaf

for this particular Seiko movements there is a special movement holder specifically for the sweep chronograph hand. It allows you to push the button in for returning to zero and hold it in place. While pushing the second hand on it the proper location. It also provides support underneath C don't knock the jewel allowed because it requires a lot of force to put the chronograph hand on.

For instance this is why a lot of Swiss chronograph watches when you go to remove the hands they will disintegrate because they been put on with so much force that they basically are considered non-removable and in the service centers they would get an entire replacement hand kit which we do not get

so chronograph hands need to go on typically very very tight as others have mentioned there's a lot of force on them when the returning to zero.

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47 minutes ago, JohnR725 said:

For instance this is why a lot of Swiss chronograph watches when you go to remove the hands they will disintegrate because they been put on with so much force that they basically are considered non-removable and in the service centers they would get an entire replacement hand kit which we do not get

I have read that Breitling chrono hands disintegrate on removal but didn't know it's a common problem. 

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11 minutes ago, RichardHarris123 said:

Breitling chrono hands disintegrate on removal but didn't know it's a common problem

yes Breitling is the company was thinking of. Don't know how common it is but if you want your chronograph hands to stay in place typically a lot of force is required.

 

 

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The 6139 service guide says to use a new chrono sweep second at service... but yeah, that's not really possible anymore. I have a few NOS hands but they are being saved for something special whenever that comes along. 

The Seiko sweep chrono fits on a bit differently. The pivot is not round but is shaped like a D at the end. The idea is the hand is forced over the D and takes on the shape preventing slippage. It is possible to reshape them to round and then re-seat them but it's not without effort and it's not without risk. If your hand is slipping I would suggest checking it. A common problem is that the hand comes loose from the pipe. I've had many like this. Another problem is that the pipe has micro splits where it has been taken off and put back on, meaning it does not grip as tightly as it should. I'd check those things first if it were me.

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