I'm an idiot! Repairing a "false" cannon pinion for Universal Geneve cal 66 / 1-66 / 2-66

[Knebo]

Hey everyone..

I felt like posting this in the "safe zone" for beginners... a true greenhorn f***-up!! I'm very upset with myself.

Yesterday, I wanted to start the service of my new Universal Geneve White Shadow with calibre 2-66. I thought it was a simple cannon pinion problem because the watch was working, but hands stopped moving sometimes. And yes, the cannon pinion felt completely free.

I was in a bit of a rush -- red flag No1. Then I noticed that the cannon pinion didn't have a dent in the middle -- red flag No2. I proceeded anyway with my staking set...

 

 

 

When trying to re-install the tightened pinion, the centre wheel shaft sank down. Oh dear! But wait! Look at the train side! There's no centre wheel!!!! I'm such an idiot for not thinking about the movement design!!

 

Ok, now let me explain. The cannon pinion is supposed to be completely free! It's like a "false" cannon pinion. No friction intended. Time setting is done through a decentralised centre-wheel with a friction pinion on it (i.e. like an off-centre cannon pinion onto which the hands are not installed). The green arrow points at the friction pinion that is directly installed onto the off-centre centre wheel.

 

 

 

OK.... now I have done a big mistake.

1. I tightened a cannon pinion that should be loose (and perfectly round inside)

2. I pushed out the centre pin on which the "fake" cannon pinion was resting.

 

I think I can easily push back the centre pin. 

 

However, what do you suggest to repair the cannon pinion? Any chance?

I was thinking of two options:

A. (somehow) punching in a smoothing broach of the right diameter to open up the hole again. Then using a smoothing broach to, well, smoothen it out.

B. use a cutting broach to get back to the right diameter. Then a smoothing broach for smoothing.

Since it's a closed cannon pinion, in both cases, I'd have to cut the broaches where they have the right diameter..

 

Any (other) suggestions?

[nickelsilver]

I would run a drill in it (if you don't have a lathe then fine by hand, holding drill in a pinvice) to open it back up. It won't necessarily be a perfect hole, but there is no force here, it will work fine.  Measure the post and I'll see if I have something the right size and stick it in the Post.

 

Edit- just remembered I have a 2-66 here that's been disassembled for years. Post measures 0.35, hole gauges at 0.36.

Edited January 8 by nickelsilver

[Neverenoughwatches]

I dont see a way to push the indents back out so it looks like they will need to be removed. Cutting broaches are normally used to cut brass, may not be too effective on a cannon pinion. Would want to test an old cannon pinion's hardness on a cheap file. Other than that a hss drill bit or a small round cutting burr might take out the indent then finish off with a  smoothing broach. Will a 1mm pin polisher fit inside to smooth out ? You could reduce one in diameter to fit. 

[nevenbekriev]

OK, not big problem happened. There is simple way of 'un-tightening' cannon pinions and it can be used here easily. You need to source hard pin (HSS drill bit tail or something of the sort) that enters in the hole almost tight. I mean the original state of the hole, now the pin will enter to the point where the indent is. You will press the cannon to go to the end with some force then. Next is to use dull nail clipper and squeeze the thin part of the cannon from several different angles around the indent, this will form the tube round and calm inside again.

[Knebo]

Thanks everyone!! I'll try! 

Big shout out to @nickelsilver for just being the best guy ever. 

[Knebo]

I was able to manually drill out the hole with a 0.36mm drill bit (thanks @nickelsilver). It fits again! 

 

I also had a go at tightening the REAL cannon pinion on the decentralised centre wheel. See description in an earlier post. 

I might have over-done it a bit, but not sure if it necessarily requires correcting/re-loosening. When setting the time counter-clockwise the balance will almost stop. There's certainly more resistance in the crown than on my other watches, but it doesn't feel excessive or like breaking teeth. I'm trying to describe the resistance. On a scale from 1 (completely loose) to 10 (breaking teeth) an 4 to 6 being the ideal/normal range, I'd say it at 7 or 7.5. What do you think? 

[Klassiker]

It sounds perfect to me.