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Posted

Hey guys. I am working on a Bulova movement from the late 40s. After oiling and cleaning and replacing with correct mainspring for the movement the watch knocks. The amplitude oscillates in a regular pattern by 10-20ish degrees but near the top will knock. I have not been able to find another mainspring that works (one that was weaker that I got was too weak and I only got 250 degrees out of it in horizontal)

So I have been trying the remedies one sees online: underoiling the train, underoiling the escapement, and even oiling the pallet fork pinions but it all still knocks. 

I decided to remove the oil from the balance cap jewels and it got the amplitude down to a healthy 290 degrees.

However is this an acceptable fix? Will the balance staff grind into the jewel without oil eventually? Or is it ok?

Besides 9010 and 9415 I have some old Mobius Clock Oil 3 which I assume is thicker than the 9010. I haven't tried it yet but I assume any oil on the balance will get it knocking again. 

Is it worth trying it with the #3 or is leaving the balance jewels dry acceptable?

Thanks

Posted

I don't think running the balance jewels without oil is not correct and will eventually cause issues.  Strange this because a few years ago I had the same issue with a Bulova and my remedy was to fit a weaker spring. A amplitude of 250 is fine, for some watches such as some vintage Seiko's thats all I have been able to achieve anyway  and they run great.

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Posted

All mechanical watch movements should have train and the balance oiled. Never oil the pallet pivots. Are you sure you haven’t over oiled. Make sure you are using the correct oil for the parts. Oil the pallet stone faces, if you have done that there is no need to oil the escape wheel teeth, one or the other you do not need to oil both. The balance will need different oil from the train. Have you measured the spring against the recommended one? If a spring is to powerful that can cause knocking.     

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Posted

What is the caliber number and which springs have you tried? Were they brand new or old stock?

You may find someone on here has a spring in between they could share, or maybe try looking for a NOS Bulova spring on eBay. 

Posted
4 hours ago, clockboy said:

I don't think running the balance jewels without oil is not correct and will eventually cause issues.  Strange this because a few years ago I had the same issue with a Bulova and my remedy was to fit a weaker spring. A amplitude of 250 is fine, for some watches such as some vintage Seiko's thats all I have been able to achieve anyway  and they run great.

I think you meant to say not oiling them is incorrect right? Or that is alright and wont cause issues? Lots of negatives in there! 

It is nice to hear that 250 amplitude horizontal is acceptable. Ive always seen the statement "you should get at least 270 horizontal and 235 vertical on a near full wind". What would you say is acceptable for a vertical amplitude if you get 250 horizontal?

I used the proper 10BM spring first (NOS) 4 x 11 x 11 1/2 (which is a 1.3 x 10) like this one and only got 250 out of it

Plymouth-Mainspring-for-Bulova-10AK-10BM-Alloy

I then upped it to the next strength, a 4 x 10 x 11.5 (1.3 x 11) of the same size, like this one 

s-l1600.jpg

And it knocked. I was not able to find a 1.30 x 10.5 in between the two

Posted

Generale Ressorts has a 1.30 x 0.105 x 280 ref. 3267 and a 1.30 x 0.105 x 300 ref. 3268. The latter is the correct length but you would be fine with the 280.

What did you try to increase your amplitude before increasing spring strength? That should be the last resort after all else has failed. I also agree that 250 for that watch is OK if it's timing well.

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Posted
5 minutes ago, nickelsilver said:

Generale Ressorts has a 1.30 x 0.105 x 280 ref. 3267 and a 1.30 x 0.105 x 300 ref. 3268. The latter is the correct length but you would be fine with the 280.

What did you try to increase your amplitude before increasing spring strength? That should be the last resort after all else has failed. I also agree that 250 for that watch is OK if it's timing well.

Just found the above springs as Nickelsilver says. According to the catalogues, the GR 3254 which is 1.3 x 0.1 x 300 is the correct spring fo this watch. You may find that the NOS one you bought has set and therefore a brand new one may be better.

Did you clean and re-oil the new spring or use as is? May be that the oil on it has degraded?

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Posted

Thanks guys, I have not used GR before. I see I have to request their catalog. While that happens what is your experience with their cost of mainspring and shipping to US?

 

Edit: I realized it is their mainsprings I have been buying from Cousins this whole time.

Posted

Looks like the GR 3267 is the right way to go Is anyone aware of a US based seller of GR mainsprings? Cousins UK is great but I prefer faster delivery times!

Posted
2 hours ago, patchwerk said:

Thanks guys, I have not used GR before. I see I have to request their catalog. While that happens what is your experience with their cost of mainspring and shipping to US?

 

Edit: I realized it is their mainsprings I have been buying from Cousins this whole time.

You can find the GR catalogue here https://www.cousinsuk.com/document/category/mainsprings-by-size-watch-pocket

or use Cousins search tools, or this list https://watchguy.co.uk/cgi-bin/mainsprings

Jules Borel stocks them in the US.

There used to be a material suppliers section on this site but it seems to have been removed :(

 

 

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