My Grandfathers Watch

[LeCorbusier]

My centre wheel pivot?

[nickelsilver]

Yes, I think if you wipe off the oil you'll see that it doesn't have the same form as in my pic. From the surface finish visible it looks like there was an attempt to modify it with a rough stone or file, and the sloping area was lost in the process. Why it was done is a mystery; could be the center wheel was changed in the past with one that was almost correct, but didn't fit the cannon pinion, or perhaps the cannon pinion was changed, was too tight, thus the stoning in either case, or both.

[LeCorbusier]

I have cleaned off the oil ... sorry for not doing that earlier ... here is the cleaned version.

[nickelsilver]

Hmm, ok. It has the right shape, still looks like it's been "modified" in the past. If the old one was riding up that's a sign that the divot was put too high; it's not making good connection with the slope. If the new one is too tight to fit all the way it could be that the diameter of the center wheel shaft is too large near the actual pivot portion (which from the photo could be true). Or it could be the divot in the cannon pinion is simply too much. My gut feeling is the former. If I had it here I would carefully check the diameter of the shaft, at the shoulder and further up, to be sure it's cylindrical, then gage the hole in the cannon pinion with a plug gage, then do whatever modification necessary. Do you have a micrometer?

[LeCorbusier]

I'm kind of thinking my best option might be to order a new 7040 centre wheel? very much starting out here.

[nickelsilver]

13 minutes ago, LeCorbusier said:

I'm kind of thinking my best option might be to order a new 7040 centre wheel? very much starting out here.

Something looks fishy to me about the one you have, not up to the quality I would expect from Peseux. I wouldn't be surprised at all if it solved the issue.

[LeCorbusier]

Fishy it was indeed! The replacement centre wheel took the Canon Pinion nicely and all works well. Under the microscope it wasn't vastly different, just more crisp. Apologies that I forgot to take a picture.

 

[watchweasol]

Nice to get a result   well done.

[LeCorbusier]

My next problem is that the minute hand is very loose on the cannon pinion. So if it sits still it keeps time beautifully, but when wearing the hand slips round.

 

Is there a simple way to tighten/secure?

[watchweasol]

Hi they can be c;osed by nipping it up in a pin vise if the tube is long enough if not there are punches which are countersunk that to place over the hand from the back and tap down closing the small tube. there are also propriety btanded toold for the job.