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How to loosen cannon pinion?


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My 11DP beginner saga continues.  I've managed to press too hard on the cannon pinion while putting it on the center wheel.  I think the bottom jewel moved as end shake is high and amplitude dropped.  I have a donor main plate that I can rebuild. How does a beginner loosen the cannon pinion just enough to prevent moving the jewel again??

Helpless in Maryland

Charlie

 

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Loosen or tighten? For press fitting it back in just use gentle pressure with tweezers until it clicks in. To remove the cannon pinion safely you should use a cannon pinion removal tool but there are other alternatives.

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If overtightened to the point it can't be preesed back on the arbour, you should broach it back to size. 

In case you can press it back in place without damaging anything, but it just feels too tight, try adding a bit of oil, keep turning it as you would when setting time, this somewhat loosens it, remove, clean, grease and reinstal.

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Hi Charlie,

In the old German and Swiss repair literature you find that it is good practice to support the bridge holding the centre wheel before you press on the cannon pinion. Ideally this is done with a staking tool. You select an anvil to rest the bridge and the jewel. Then you press in the cannon pinion with a hollow flat punch. I have never laid hands on a bulova 11dp but if the highest point of the balance side of the movement is the rachet wheel you will still have air between centre wheel jewel and bench. If you place it in a movement holder you have a lot of air between jewel and the bench. That's lethal and as you experienced can push out the jewel in a worst-case-scenario

IMG_20201002_142742.thumb.jpg.25cae7015a087fa259679da9209604e8.jpg

I don't have a better picture on my mobile and you can't see the anvil under the plate. The cannon pinion of this pocket watch also looks a little different but you can see the basic layout. If you don't have a staking tool you can always rest the movement on a piece of steel.

Best wishes from Hamburg, Germany

Alex

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On 11/22/2020 at 7:01 AM, Lc130 said:

 I've managed to press too hard on the cannon pinion while putting it on the center wheel.  I think the bottom jewel moved as end shake is high and amplitude dropped.  I have a donor main plate that I can rebuild. How does a beginner loosen the cannon pinion just enough to prevent moving the jewel again??

 

If this was an original cannon pinion, then it should not require any excessive force while replacing it. Good cleaning inside, a little bit of oil on the centre wheel pivot, and a gentle push with tweezers straight down. Only once i had similar experience on a very-very old / crappy movement. What i did, i installed the cannon pinion BEFORE installing the bridge with bottom jewel. Yes, it was a bit tricky, and i did it under microscope while keeping the plate in vertical position, but it took just a few seconds using two punches from my trusted K&D staking tool. Everything was done by hands without using brutal force.

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On 11/24/2020 at 9:24 AM, Poljot said:

What i did, i installed the cannon pinion BEFORE installing the bridge with bottom jewel.

Under the microscope I was able to see that the bridge jewel got pushed in.  I compared it to a donor.  I swapped the donor bridge in and then did exactly as you did.  It worked.  Thank you for the tip.

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49 minutes ago, Lc130 said:

Under the microscope I was able to see that the bridge jewel got pushed in.  I compared it to a donor.  I swapped the donor bridge in and then did exactly as you did.  It worked.  Thank you for the tip.

I am glad to hear that my suggestion worked for you. I am about to replace a cannon pinion on Illinois pocket watch right now and will follow my own advice 🙂 as the lower jewel is secured by three tiny screws.  

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