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Loose Center Wheel Pinion in M 102 Movement


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Hello everyone!

 This is my first time posting here, so please bear with me if I’m not used to the structure or layout of how to properly use the forum. 

So, I have an issue with this movement which is labeled M 102, and had a curious arrow-triangle engraving on the barrel bridge. I bought this watch for cheap, and even once I screwed a new crown onto the stem (old crown was broken and lost before I got it), it wouldn’t take a wind. I opened it up, and observed the ratchet wheel spinning with no resistance when winding. So my first though of course was a broken mainspring. But in fact, the mainspring, mainspring hook, and the hook on the barrel arbor were all in superb condition (albeit dirty covered in old grease). 
 

So my next thought was to see what was happening more closely when winding. And it turns out, when winding, the entire barrel spins with the ratchet wheel! Okay, so broken escapement? But no, the train of wheels didn’t move at all while the arbor spun.

FINALLY I looked at the next step in the train of wheels, the center wheel. With just the barrel and the center wheel fitted, the center wheel is turned properly. But with ANY resistance (such as the third wheel being put in), the center wheel itself stops, and the center wheel pinion spins freely, loose in the wheel.  With the wheel removed, at one point I put it in a pin vise (with BARELY any pressure applied) to showcase just how loose the wheel actually is, and it is very barely on there, able to spin and wobble freely  

Attached are pictures of the center wheel removed from the movement.  Also attached is a picture of the engraving on the barrel bridge to help ID the caliber if I haven’t already. 

So, my question is, does anyone have any reference material, or perhaps know which stake/method I should use to stake this pinion back tight into it’s wheel?

 

Thank you so much!

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Edited by Isochrono95
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When they are this loose it's not certain you can re-rivet it, but it's always worth a try. You want a hole in your staking tool's die that allows the pinion to sit squarely on the leaves, passing the pivot and shoulder through the hole. The stake should be round faced, with a hole that passes the shoulder and securely sits on the leaves that form the rivet. You'll want to be firm with your hammer strikes, and after 6 or so check to see if anything is happening. If it's not, you might need a bigger hammer, seriously. I have 3 main hammers at the bench, one is about 20 grams (really light), the one I use most for staking staffs and such is about 45 grams, and another that's 60 something grams. I would go for my 60 gram for this job.

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7 hours ago, nickelsilver said:

When they are this loose it's not certain you can re-rivet it, but it's always worth a try. You want a hole in your staking tool's die that allows the pinion to sit squarely on the leaves, passing the pivot and shoulder through the hole. The stake should be round faced, with a hole that passes the shoulder and securely sits on the leaves that form the rivet. You'll want to be firm with your hammer strikes, and after 6 or so check to see if anything is happening. If it's not, you might need a bigger hammer, seriously. I have 3 main hammers at the bench, one is about 20 grams (really light), the one I use most for staking staffs and such is about 45 grams, and another that's 60 something grams. I would go for my 60 gram for this job.

First of all, thank you very much for your advice, I’ll reread it many times to make sure I’m understanding correctly. Also, I was looking at my staking set last night and found a few round stakes with holes that met that description. My next issue is, the holes in those stakes are only about 2mm deep, or at least not deep enough to fully receive the center wheel arbor and give me enough reach to reach down to the wheel and rivet. I have a few stakes with larger diameter holes that are drilled deeper, but at that point I don’t think the stake would be hitting close enough to the arbor (or at all) to rivet it correctly. I wonder, do people often go about drilling the holes on stakes deeper as needed? Thinking that might be what I have to do here. 

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7 hours ago, nickelsilver said:

I have 3 main hammers at the bench, one is about 20 grams (really light), the one I use most for staking staffs and such is about 45 grams, and another that's 60 something grams. I would go for my 60 gram for this job.

A little off topic...but when you are riveting a staff, which of these do you use.  I am always SOOOO paranoid when I go whacking a stake with a hammer.  I have two hammers.  One is light and the other is rather heavy.

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8 minutes ago, LittleWatchShop said:

A little off topic...but when you are riveting a staff, which of these do you use.  I am always SOOOO paranoid when I go whacking a stake with a hammer.  I have two hammers.  One is light and the other is rather heavy.

The medium one, which I'd say is a "normal" watchmaking hammer.

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11 hours ago, nickelsilver said:

You'll want to be firm with your hammer strikes, and after 6 or so check to see if anything is happening. If it's not, you might need a bigger hammer, seriously.

That's what I've always said; "Never use force, get a bigger hammer!" 😉

Well, reading your post, I realised I don't own a decent hammer for riveting balance staffs. I've whacked the stakes with what I could get hold of (too embarrassed to mention any examples). So what exactly should I try to get hold of?

image.png.2b0206ed9428e8143c1e928fee6b10ab.png
Riveting hammer

image.png.d0ca47d976a2b9ec621129d11e4a1dd1.png
Watchmakers hammer

I searched Cousins and found what they call a "Riveting hammer" and a "Watchmakers hammer". They have a riveting hammer that weighs 45 grams, a watchmakers hammer that weighs 40 grams (Bergeon), and a watchmakers hammer that weighs 50 grams (CousinsUK). What would be a good pick for riveting a wristwatch movement balance staff?

 

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