Lift Angle for old Bulova

[margolisd]

Hi folks. Long time no post. Having a baby means there is less time for watches

Does anyone know the lift angle for the Bulova 10A series of watches from the 1920s. I'm trying to get an accurate reading on a movement I'm repairing. In particular I have a 10AI. I couldn't find the lift angle anywhere so I tried to calculate it using this method. The result was 59 degrees. But that seems quite unusual...

 

[rogart63]

Should think you will be fine with using 52 degree . I have never seen a movement that has 59 degree lift angle . If you look at the other Bulovas they are around the same . 50 -53 . There would not be much different if you set it to 50 or 52 degree . 

[jdm]

Worth to note for the casual reader that since lift angle only affects amplitude calculation by a small amount, it is perfect possible to asses and regulate with a discording value.

[watchweasol]

Hi according to the lists Bulova 10 CK to 10CRAC are all at 50

[margolisd]

Thank, yes I spotted those on the lists. There seem to be a set of 10s that are very different. All from them 60s. Mine is from the 20s. It's similar to this:

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&2&2uswk&Bulova_10AE

Thanks for your advice. I think I'll just leave the machine on the default 52 and see how I go

 

[mbwatch]

Just to add a data point to an old post on weird Bulova lift angles:

I have a Bulova 10BC (late 1940's) which is running strongly with a new genuine Bulova mainspring. Weishi 1900 at lift angle 52° tells me it is reaching only 215° but visually it's obviously is much higher, making just short of 1.5 full turns of the balance. Winding it to 180° visually to set the lift angle accordingly puts it way up at LA 58°. But then still at full wind the TG only reads at 230° when it is clearly closer to 270° on slow-mo video. The trace is otherwise nice and clean, beat error at 0.1ms.

I'm going to try not to think about it anymore. Either this caliber has a wildly high lift angle or the Weishi machine just can't get a good read on it.

Edited March 9 by mbwatch

[JohnR725]

  On 3/9/2025 at 2:39 AM, mbwatch said:

wildly high lift angle

Expand  

I have a link below which list of lift angles.If you go through the list 52 appears to be the average but there are lower lift angles and higher lift angles. It's why the timing machine has a range of 30 to 70. So yes it is possible the watch has a higher lift angle.

https://watchguy.co.uk/cgi-bin/lift_angles

  On 3/9/2025 at 2:39 AM, mbwatch said:

the TG only reads at 230°

Expand  

Is this the TG software?

[mbwatch]

  On 3/9/2025 at 6:21 AM, JohnR725 said:

Is this the TG software?

Expand  

Sorry no, I was ambiguously abbreviating the Weishi 1900. I had been over a few lift angle lists including watchguy and found none specifically listing the Bulova 10BC, but its contemporary Bulovas were mostly 52 as is the AS1200 base caliber.

[JohnR725]

  On 3/9/2025 at 1:18 PM, mbwatch said:

Sorry no, I was ambiguously abbreviating the Weishi 1900. I had been over a few lift angle lists including watchguy and found none specifically listing the Bulova 10BC, but its contemporary Bulovas were mostly 52 as is the AS1200 base caliber.

Expand  

The reason I wanted it clarify is there is a software-based timing program labeled TG for which I'm not overly impressed with and occasionally people using on the discussion group. Which is why just wanted to make sure I was understanding.

Then other places to find lift angles but not entirely helpful are PDFs. So basically companies that produce timing machines early on that could measure amplitude would have a lift angle listing so people would know how to use their newfangled timing machines. One of the listings that are not sure where it actually even came from my butt on a spreadsheet that somebody made. Then there is the one that came from witschi with bonus where the sounds come from and our oscilloscope diagrams which unfortunately did not seem that entirely resemble the real world. I think they're more of an exaggeration of what things may or may not look like

then the oscilloscope brings up the problem of it would be really nice if all the timing machines could actually do a oscilloscope. Then not just the oscilloscope it be really nice if they did what Sort of what witschi does an added show what they're triggering off of. I use the wording is sort of in that I wish that they would shift the display a little bit so you can see the beginning were clearly. But they will usually show you what they're triggering off of for locking and this is where you typically will see variations of basically the timing machine is not triggering exactly where it's supposed to be.

This is where sometimes it's amusing to look at the witschi our oscilloscope at work and noticed that it gets confused a lot of times especially when I'm working on pocket watches and I don't really think they had pocket watches in mind when they made their timing machine.

Then I just now doing a search for lift angle in the computer I see another listing that I hadn't already attached. Amusingly I find another one in the computer not attaching it because it only has one Bulova watch how strange?

Then the amusing pocket watch listing?  Why is it amusing because  I've actually seen it quoted on the Internet wherever I last placed at somebody found it quoted it someplace else.. Then the other day at work they were apparently looking for lift angles for pocket watches and found the list and noticed it came from me my list.. But I find quite interesting that no one else is bothered to make a listing of their pocket watches..  So the early days where I worked my boss was much more obsessed with amplitude now I typically just don't worry about it if the numbers are the way to hire way too low I might just adjust the lift angles the numbers look more realistic but I don't worry about it typically unless they're extremely low then I may be more concerned than actually bothered to set the lift angle otherwise I typically just don't worry about it..

 

Lift Angle big list .pdfFetching info... Lift Angles Watch gamma lift angle.pdfFetching info... Lift Angles Watch Witschi Electronic AG.pdfFetching info... Lift-Angles Wostep.pdfFetching info...