Crazy Timegrapher Results

[gpraceman]

I'm working on my Grandfather's Benrus tank watch, with Model BA movement, that I inherited.  I am puzzled by the timegrapher results. Dial down gives some really puzzling results. Other positions that I have tried are more what I expect.  I have already serviced the movement.  I didn't see any problems with the pivots or jewels.

What should I focus on?

Dial Up:

Dial Down:

Crown Up:

Crown Down:

Edited October 15, 2024 by gpraceman

[Neverenoughwatches]

What is a major part of a movement when amplitude is good that has lots of adjustment and affects the rate more than anything else.....?   

[nevenbekriev]

My advice will be to check for overbanking in DD position. Amplitude readings... Learn to see amplitude by observing the balance, what is seen on timegrapher is not always relevant. Of course, it may be some kind of hairspring problem, but may be just stronger mainspring. There is difference DU/dd, which needs investigation.

[gpraceman]

1 hour ago, nevenbekriev said:

My advice will be to check for overbanking in DD position. Amplitude readings... Learn to see amplitude by observing the balance, what is seen on timegrapher is not always relevant. Of course, it may be some kind of hairspring problem, but may be just stronger mainspring. There is difference DU/dd, which needs investigation.

Not sure it will help, but here's a bit of video on the balance wheel rotation while in DD position.  It doesn't seem to be breathing right.  More compression on the one side than the other.  Though, I really haven't serviced many that don't have Breguet overcoils, so maybe that is breathing fine.

 

 

Edited October 15, 2024 by gpraceman

[thor447]

I could be way off, but looking at the balance pivot when running in DD, it looks like there is a bunch of vertical movement.  End shake on the balance wheel perhaps?  Did you check the roller jewel engagement with the pallet fork in DD?

[Neverenoughwatches]

55 minutes ago, gpraceman said:

Not sure it will help, but here's a bit of video on the balance wheel rotation while in DD position.  It doesn't seem to be breathing right.  More compression on the one side than the other.  Though, I really haven't serviced many that don't have Breguet overcoils, so maybe that is breathing fine.

 

 

If the hairspring is not centered to the balance then the tighter coils side can touch together if the full contraction moment of the spring is also on that side....equally on the expansion side the outer coil could be hitting something. Would expect all positions to be affected. How about magnetism.....not of the hairspring but of something else ? Something close thats pulling the hairspring? 

14 minutes ago, thor447 said:

I could be way off, but looking at the balance pivot when running in DD, it looks like there is a bunch of vertical movement.  End shake on the balance wheel perhaps?  Did you check the roller jewel engagement with the pallet fork in DD?

Keener eye than me Adam if you can see that , video is too fast for me 

1 hour ago, gpraceman said:

Not sure it will help, but here's a bit of video on the balance wheel rotation while in DD position.  It doesn't seem to be breathing right.  More compression on the one side than the other.  Though, I really haven't serviced many that don't have Breguet overcoils, so maybe that is breathing fine.

 

 

First order thats quick and removes doubt would be to demag the movement.  I then say you need to pick it up and look through the movement in different positions to see what the hairspring is doing. If its not hitting anything, is flat and level, then does it look nice and round, concentric coils, check it for center over the balance jewel if you're not sure. 

[gpraceman]

23 minutes ago, Neverenoughwatches said:

If the hairspring is not centered to the balance then the tighter coils side can touch together if the full contraction moment of the spring is also on that side....equally on the expansion side the outer coil could be hitting something. Would expect all positions to be affected. How about magnetism.....not of the hairspring but of something else ? Something close thats pulling the hairspring? 

I have demagnetized the movement.  I would think that an off center hairspring collet would also affect other positions.

I have looked under high magnification and don't see the hairspring touching anything.

I had a much more reasonable DD timegrapher result prior to service.  So, what has changed?  Well, it has a new mainspring.  I tightened up the upper barrel arbor hole in the barrel bridge a bit.  I also reduced end shake on the pallet fork (jewel on the pallet bridge was a tad high).  When finding this issue, I tried to reverse that change, but it didn't affect the results.

[nickelsilver]

I think your new mainspring is stronger than the original. What size spring did you put in?

[Neverenoughwatches]

1 hour ago, gpraceman said:

would think that an off center hairspring collet would also affect other positions.

 

2 hours ago, Neverenoughwatches said:

Would expect all positions to be affected.

Mostly yes, but the hairspring isn't exactly the same shape or hang the same through all positions ( amplitude dependent ) , it can also catch things in different positions and in vertical positions the amplitude can drop enough so the contractions and expansions are lesser.

[spectre6000]

I second the rebanking theory. Been there, done that. New, potentially stronger mainspring. Highest positional amplitude. Super high rate gain in the one position. Looks normal visually. Seems like kind of a low amplitude to start rebanking, but not impossibly so. If you have the ability to adjust the pins, you might see if you can narrow them up a bit without causing problems. Won't likely take much, and will at least be a good test if not a fix.

[praezis]

Was the watch fully wound then?

If DD shows knocking, it should disappear with less winding.

Next to +467 there are -9 results. Was the ‚crazy‘ result intermittent only?

Frank

[gpraceman]

I was able to move the problem to the DU position by changing the height of the stud pin in the balance bridge.   Initially, I had the stud pin in as far as it would go (I had removed the balance wheel from the cock to clean the pivots).  I loosened the stud screw and let it find the position that it wanted to and tightened it back up.  The craziness moved to DU.  Fiddled with stud position, to get the mainspring to lay flat, but that brought the problem back to DD.

I'm not sure what you call this type of regulating pin arrangement.  You need a screwdriver to rotate the one side to release the hairspring.  There's a little ledge that sticks out from that rotating piece and the hairspring could be rubbing on that.

It does look like the regulating pin gap needs to be minimized.

 

9 hours ago, nickelsilver said:

I think your new mainspring is stronger than the original. What size spring did you put in?

I measured the old mainspring at 1.6mm x 0.11mm x 9mm and that is what I ordered.  Got it from Cousins, GR4514.

Emmy Watch does list mainsprings with slightly different specs.

https://www.emmywatch.com/db/movement/benrus--ba/

 

3 hours ago, spectre6000 said:

I second the rebanking theory. Been there, done that. New, potentially stronger mainspring. Highest positional amplitude. Super high rate gain in the one position. Looks normal visually. Seems like kind of a low amplitude to start rebanking, but not impossibly so. If you have the ability to adjust the pins, you might see if you can narrow them up a bit without causing problems. Won't likely take much, and will at least be a good test if not a fix.

There does seem to be a bit much gap between the regulator pins.  I will try to adjust that.

 

3 hours ago, praezis said:

Was the watch fully wound then?

If DD shows knocking, it should disappear with less winding.

Next to +467 there are -9 results. Was the ‚crazy‘ result intermittent only?

Frank

Yes, fully wound.  Though, I let it run overnight and checked it this morning and it was still acting bizarrely.

It can be intermittent.  The timegraph can look more normal, then start going awry.  Once awry, though, I haven't seen it go back to normalcy unless I change the position and then go back to DD.  That is not always the case, though.

Edited October 15, 2024 by gpraceman

[nevenbekriev]

What is seen on the first video (by the hairspring breathing) is that the amplitude is really high. The other thing seen is that when expands, the hairspring probably touches the stud. So, what You can do is center the hairspring better as it will stay a little away from the stud. Then, check You amplitude. One way to do it is to put a dot with marker on the balance rim and observe it's movement. The other way is to check if the lift angle for the movement is different from the magical number 52 and insert the correct number in the timegrapher. And if really rebanking happens, then You can return the old spring and check what will happen then. Yes, You can close a little the regulator pin. But it will not solve the problem.

[gpraceman]

50 minutes ago, nevenbekriev said:

What is seen on the first video (by the hairspring breathing) is that the amplitude is really high. The other thing seen is that when expands, the hairspring probably touches the stud. So, what You can do is center the hairspring better as it will stay a little away from the stud. Then, check You amplitude. One way to do it is to put a dot with marker on the balance rim and observe it's movement. The other way is to check if the lift angle for the movement is different from the magical number 52 and insert the correct number in the timegrapher. And if really rebanking happens, then You can return the old spring and check what will happen then. Yes, You can close a little the regulator pin. But it will not solve the problem.

I haven't found the lift angle for the Benrus BA movement.  I did find 51 degrees being the lift angle for several other Benrus movements, so I have tried that.  Not much of a difference in amplitude reading from 52 degrees, of course.

I'll attempt to center up the hairspring collet and tweak the position of the regulating pin and retest.  Trying the old mainspring is certainly an option, but it is quite coned.  Plating was worn off of the barrel lid, so this wasn't from me removing the mainspring.

Edited October 15, 2024 by gpraceman

[RichardHarris123]

12 minutes ago, gpraceman said:

quite coned

Maybe one of the largest understatements I've ever heard. 

[gpraceman]

Well, an off center hairspring collet is not the issue.  So, I'm left trying the old mainspring in it.

[Neverenoughwatches]

59 minutes ago, RichardHarris123 said:

Maybe one of the largest understatements I've ever heard. 

Absolutely,  i cant see that would even work, maybe release a coil or two at best.

8 minutes ago, gpraceman said:

Well, an off center hairspring collet is not the issue.  So, I'm left trying the old mainspring in it.

That rules one thing out, i was going with the hairspring catching or coils touching ( which it still looks like it could be )As suggested visually check the amplitude,it might be a bit more than your tg is telling you. The oscillations in youf first video look strong, strong enough to rebank and push coils together. I had something like this a few months back the coil spacings looked really small and the amplitude was high enough to bring them together.

[nevenbekriev]

Yes, the spring is coned. Actually, I have never seen spring that much coned. But I can argue if it will not work or release only 2 coils . Thinking in this direction, I can guess that the spring has been coned on purpose and this purpose is to reduce the amplitude...

OP, The hairspring looks great, but I still will advice to enlarge the space between the outer coil and the rest. Bend a little in the point I have marked on the picture.

 

[Neverenoughwatches]

7 minutes ago, nevenbekriev said:

But I can argue if it will not work or release only 2 coils . Thinking in this direction, I can guess that the spring has been coned on purpose and this purpose is to reduce the amplitude...

You know better than me Nev , ive never seen one this coned before . But i did actually wonder if this had been made this way for a reason as i cant see it becoming this bad any other way. Reminds me of the 80's craze toy ' Slinky '

[gpraceman]

I tried with the original mainspring.  Had to wind it in by hand as the coning was causing me a problem trying to use a mainspring winder.  Amplitude is significantly less, but I don't see that weird problem in any position.  So, I'll look at getting a new mainspring.

Here's what I ordered, based on what I measured from the old mainspring:

• 1.60 x 0.110 x 300

Here's what Emmy Watch lists:

• 1.55 x 0.105 x 280
• 1.50 x 0.110 x 300

Looking on eBay, I see a Benrus BA mainspring with a spec of 1.50 x 0.11 x 318 mm.

Those don't seem much different from the new one that I got.

 

[nevenbekriev]

If You order springs with 0.11 strength, then You probably will get the same big amplitudes. The movement is actually ETA900 I guess and from Ranft database, the spring should be 1.55/0.10/290

[AndyGSi]

I've found various different sizes for the mainspring.

I think one of your problems here could be the 1.6 is tool big for the barrel.

[spectre6000]

20 hours ago, gpraceman said:

There does seem to be a bit much gap between the regulator pins.  I will try to adjust that.

I meant the pins on either side of the pallet fork. The banking pins. The fork isn't where it's supposed to be, and the balance wheel is hitting it on the back end. ...is my theory based on the timegrapher.

[gpraceman]

8 hours ago, nevenbekriev said:

If You order springs with 0.11 strength, then You probably will get the same big amplitudes. The movement is actually ETA900 I guess and from Ranft database, the spring should be 1.55/0.10/290

ETA 900 is the base movement.

8 hours ago, AndyGSi said:

I've found various different sizes for the mainspring.

I think one of your problems here could be the 1.6 is tool big for the barrel.

The lid closes no problem, but the height I've seen listed for this movement is 1.5 or 1.55 mm.

2 hours ago, spectre6000 said:

I meant the pins on either side of the pallet fork. The banking pins. The fork isn't where it's supposed to be, and the balance wheel is hitting it on the back end. ...is my theory based on the timegrapher.

Not sure that I want to mess with those.  A less strong mainspring seems the better way to go.

[Neverenoughwatches]

4 minutes ago, gpraceman said:

The lid closes no problem, but the height I've seen listed for this movement is 1.5 or 1.55 mm.

Can you measure the height needed from inside the barrel .