Jump to content

First balance staff replacement!


Recommended Posts

Oh boy this was hard. 

So I had an A-17 Waltham 6/0 military watch with a busted staff.  The first one I ordered was incorrect.  The second one I ordered was correct.

I watched this WRT video about a dozen times: "Fitting a new balance staff to a vintage 1940s cyma www military watch"

I read the Bulova training manual (fitting a balance staff) that somebody posted the other day.

Once I was comfortable with the process, I dove in.

Imagine that, just like on the video, the roller came off in two pieces.

Removing and installing the staff went off pretty much like the video said.  I used a truing tool to make some slight tweaks until I figured any more fiddling would make it worse.  Then on to assembling the broken roller.

I had taken pictures of the balance in all positions, so I knew how it had to go back together.  Got it on, and examined under a microscope and was happy.

Then I put the hairspring on without any issues.

This is where it became incredibly hard.  The way the hairspring is shaped (pretty odd), it was nearly impossible to get the hairspring into the regulator pins while getting the stud in place.  At one point I thought I had it so I turned over the balance and cock to see how it hung.  Something jiggled and the hairspring looped over the stud screw.  Rather than take a chance of bending the hairspring, I removed the screw so that the hairspring would fall away.  So, with the undamaged hairspring away, I had the task of getting that damn set screw back into the cock.  With my dad's copious amount of tools, I found one that is like a locking tweezer with a round hole in the end.  I locked the screw in this and had plenty of control to put it back where it came from!

After much fiddling I finally got the hairspring installed with the stud in place and the hairspring properly installed in the regulator pins.

Then, I put the balance back into the watch and it started ticking!  Wow...what a great feeling.

This took me about 3 1/2 hours (starting with a disassembled balance that I had started over a week ago).

2021-03-22 22_39_21-Photos.png

  • Like 7
Link to comment
Share on other sites

Getting those screws in is a real pain.  My method is to use a very very small piece of rodico (or bluetac if no rodico), push the screwdriver through the rodico, engage the slot with the screwdriver and push the screw/driver back onto the rodico so the screw is held.  The screw can then be fitted easier and once engaged the rodico can be removed.  A dial dot also works but can leave adhesive on the screw which needs to be cleaned off.    Plastic magnetism !!

Edited by canthus
  • Like 1
Link to comment
Share on other sites

Here is a picture of the hairspring showing how it takes an abrupt turn crossing over the coil and then to the stud which lies inside the circumference of the outer extent of the hairspring.

When I took the watch apart (weeks ago), I thought I had damaged the hairspring.  Nope.  This is the way it is designed.

Any thoughts on this configuration?  Seen before?  Reason?

2021-03-23 07_00_08-Photos.png

Edited by LittleWatchShop
add photo
Link to comment
Share on other sites

47 minutes ago, LittleWatchShop said:

Here is a picture of the hairspring showing how it takes an abrupt turn crossing over the coil and then to the stud which lies inside the circumference of the outer extent of the hairspring.

When I took the watch apart (weeks ago), I thought I had damaged the hairspring.  Nope.  This is the way it is designed.

Any thoughts on this configuration?  Seen before?  Reason?

 

That is a Breguet Hairspring, basically it is superior to one that just spirals out.

Have a read of these sites.

https://www.buzzufy.com/blog/2018/09/24/the-breguet-or-overcoil-hairspring/

 

https://www.breguet.com/en/history/inventions/breguet-balance-spring

  • Like 2
  • Thanks 1
Link to comment
Share on other sites

1 hour ago, LittleWatchShop said:

 Reason?

I guess the articles Tmuir provided link to does explain some resason, here is what I figure,

Some advantages; The diameter of overcoil gets increasingly smaller as you get closer the stud so hairspring  moves less between regulator pins during oscilation,  therefore isochronicaly enhanced  , almost as good as free sprung.

As you can see breguet hairspring allows longer length therefore bigger amplitude of oscilation.

Both effect directly increase percision of regulation.

Disadvantage,  tall balance staff.

  • Like 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • 🤔 leaving the EU meant that UK was no longer part of the convention and have already been turned down an independent reapplication. I'm pretty sure courts have to be held in Switzerland in this case. There will be a lot more watches stashed away in draws  tbh, folk wont be able to afford to maintain them. Cheap watches will be bought and top end watches by folk with plenty of cash that can pay for service and repair. The expensive once in a lifetime gifts and everything else inbetween will be at the forgotton when they stop working. I know i was being a numpty, get used to it 😄 Anybody that knows will boycott them, but besides repairers who will know. Nope will never buy one, i made that decision as soon as i learnt about this. 
    • although not in this case.  It was the Lugano Convention and its deficiencies that allowed a Swiss court decision in the first place.  This isnt really a Brexit issue at all.  A decision that affects both the EU and the UK should never have been heard in Switzerland. I bet the authorised service centres in the UK are pretty pleased.  It's a massive shame, though; I believe watch owners should be able to choose to have their watch serviced by whoever they trust.
    • Hi guys I think that old hippy is correct, it opens the gates for china to manufacture aftermarket spare parts. considering that they already do work on behalf of the Swiss I guess this decision gives the a little more legitimacy to tool up and I am sure they will take advantage of the situation either with or without the blessing of the Swiss watch industry  Having read about the protectionist machinations of the Swiss in the history of Europe they were the only ones to get fat at everybody else’s expense. I think the outcome could have been guessed at but ,  fair play to Cousins UK for standing up to them.  Now the question,  will everybody boycott Swiss watches and Swatch, no way they will still fill their coffers.  Me I stick with the Japanese once renowned for cheap shitty watches who came good through industrial effort and don’t for get the Russians that most dismiss as low grade crap. Wouldn’t buy a swatch product ever how about you all.? a
    • Hold the crown when in winding position, move the click away from the crown wheel, and then while holding the crown let it slowly unwind. I recollect that you must remove the automatic device bridge first, but maybe I'm wrong. You can first try without removing the automatic device bridge.
×
×
  • Create New...