Verge Fusee Runs for hours then stops maybe overbanking?

[bobolink]

I have just gotten back to an old verge fusee project that i got help with a long time back in this forum.  I just got it going and am happy with how it runs except for one problem.  It stops after potentially running for hours.  I can wind it fully or partially fine, it runs in all positions without stopping. I believe it is in beat.  But randomly, could be many hours of just sitting and running, it will stop and a flick of the watch in balance wheel rotational direction will start it again.  Or just a push on the balance wheel.  A puff of air is not enough to get it restarted.

I have replaced a way too damaged hairspring using a NOS pocket watch spring that was as close as possible to the original in size.  I cut it to length and reshaped it to match the coils of the original and fit.  But I knew it was slightly thicker and higher (.237mm vs .207 and .054mm vs .045) so that may be a complication if its overbanking. 

I think it might be overbanking as there are no banking pins of any kind on the balance wheel, bridge, etc.  But I cant prove that is the problem.  The watch doesnt have flags but a one piece staff with concave structures where the flags would be.  I included a pic. Not sure what these are called if not flags.   I can only see the bottom of the balance staff once installed so I cant see if the top concave is stuck against the crown wheel.  The bottom one appears to be positioned correctly when it stops and doesnt appear to be where it is stuck so I am assuming it is the top concave.  Of course I can be delusional about this as still learning.

The randomness of the problem, long running time, and it not being related to position has me unsure. 

Note I removed the regulator during the process of elimination to get it running and havent yet put it back.  I didnt think that should cause it to overbank as I assume without the regulator it runs slowest possible.  I could move the hairspring collet or at the pin to shorten the balance spring altogether if the size is just moving too fast causing the overbank If anyone thinks that is the possible.

Any thoughts out there on how to tell if its overbanking?

PS: I  realized I have no full picture of the balance staff uninstalled.

Thanks,

Bob

[KarlvonKoln]

Following, as I wish to learn more.  I have an old verge-fusee with a flag-staff.  Mine is in pretty good shape, running to within +/- 1 to 2 minutes per day (which for this kind is nigh miraculous, I'm told).  But I only knew enough to clean it (keeping the delicate chain straight and supported) inspect it for wear, oil it with heavier pocket watch oil, and regulate it as best I could. I also needed to burnish the pivots and put in one bushing into a worn hole.  It has not *yet* put forth any anomalies but I like to be prepared.

[nevenbekriev]

Hi Bob,

I must say that there is not such thing as overbanking in verge movements. The balance movement is limited to +/- 90 degr., in french movements may be +/-100. Normal amplitude is 60-65 degr., in good  french movements even 70. When the verge (the balance staff) has flags, the movement of the balance is limited by obsticles where the flags hit in early english movements (limitation by the flags), or with a pin on the balance rim in french and late english movements (limitation by the balance rim). Limitation is needed because if the balance is turned more, then the crown wheel will get free and will start turning fast. And when balance (verge) is returned to normal position, the crown wheel teeth will hit the flags and will grind themselves wearing fast  for only a moment as if they have worked for many years.

No mater what the torque is, the balance will not get to the points of movement limitation. Actually, the amplitude barely depends on torque. Limitation is needed when the movement is shaken or rotated suddenly, thus balance received additional impulse

If the limitation is not enough and turning the balance in some of directions causes freeing of the crown wheel (worst case) or locking of the escapement where the balance stays rotated to the limit, this will usually mean that the engagement of the crown wheel with the verge is not deep enough. But it is possible for example that the verge is rotated against the balance wheel and when limitation is by the balance rim, this makes limitation not symmetrical - the problem will happen in only one direction of balance rotation, an in the other direction the movement of verge will be far away from problem. Another reason is verge replaced with not proper one, wear of flags and crown wheel teeth...

I don't see clearly what type the verge on the picture is. If it has things similar to flags cut between the disks, then it needs limitation of the balance movement. In this case the cross section of the 'flag' part is flat and goes to the middle of the disks, like real flag. If the cross section of the 'flag' is just half circle (yes, such verges exist), then no additional limitation of balance movement is needed, the movement is limited by 'flags' hitting the crown wheel teeth.

When all in a verge movement is OK, then it will start working by itself, without need of giving impulse to the balance. More - it will be not possible to stop such movement, as balance will start oscillating immediately after releasing no mater in what position it was halted. To bring the movement in such condition, it is needed very lo friction in bearings of the balance, crown wheel and 4th wheel. Free oscillations test will show the condition of balance pivots/bearings. As verge movements are ones with recoil, the energy is constantly transferred from mainspring to the balance (when the crown wheel is turning forward) and back from balance to the mainspring (when the crown wheel turns back). That's why  the crown wheel, the 4th and even 3th have very thin pivots and the rear crown wheel bearing has axial steel plate, acting the same as cap jewel. It is important  to have all the bearings in perfect condition and the mesh between wheels and pinions to be correct.

 

 

[oldhippy]

As you have changed the hairspring to one that is a little stronger I expect that is the problem. Verge escapement are designed to run on as little power as possible with very low amplitude, in other words very little swing in the balance.    

[Neverenoughwatches]

On 9/2/2024 at 2:41 AM, bobolink said:

I have just gotten back to an old verge fusee project that i got help with a long time back in this forum.  I just got it going and am happy with how it runs except for one problem.  It stops after potentially running for hours.  I can wind it fully or partially fine, it runs in all positions without stopping. I believe it is in beat.  But randomly, could be many hours of just sitting and running, it will stop and a flick of the watch in balance wheel rotational direction will start it again.  Or just a push on the balance wheel.  A puff of air is not enough to get it restarted.

I have replaced a way too damaged hairspring using a NOS pocket watch spring that was as close as possible to the original in size.  I cut it to length and reshaped it to match the coils of the original and fit.  But I knew it was slightly thicker and higher (.237mm vs .207 and .054mm vs .045) so that may be a complication if its overbanking. 

I think it might be overbanking as there are no banking pins of any kind on the balance wheel, bridge, etc.  But I cant prove that is the problem.  The watch doesnt have flags but a one piece staff with concave structures where the flags would be.  I included a pic. Not sure what these are called if not flags.   I can only see the bottom of the balance staff once installed so I cant see if the top concave is stuck against the crown wheel.  The bottom one appears to be positioned correctly when it stops and doesnt appear to be where it is stuck so I am assuming it is the top concave.  Of course I can be delusional about this as still learning.

The randomness of the problem, long running time, and it not being related to position has me unsure. 

Note I removed the regulator during the process of elimination to get it running and havent yet put it back.  I didnt think that should cause it to overbank as I assume without the regulator it runs slowest possible.  I could move the hairspring collet or at the pin to shorten the balance spring altogether if the size is just moving too fast causing the overbank If anyone thinks that is the possible.

Any thoughts out there on how to tell if its overbanking?

PS: I  realized I have no full picture of the balance staff uninstalled.

Thanks,

Bob

What is your explanation of overbanking in this case bob ?

[nevenbekriev]

Hi Bob,

Please make some pictures of the upper and down side balance cocks. I found a picture

of down side cock and it seems You a missing the axial bearing steel plate. Sorry I have missed the questions You have asked in that thread. May be You have figured the way of adjustment, but for sure we need to synchronize terminology. Show good pictures of all regulating screws and I will try to explain the function of every one.