Bent Banking pin - why, and should I straighten it ?

[mikepilk]

I fitted 1.80x0.10x340. 

I'm trying to reason, how moving the pins out affects amplitude?  The lift angle doesn't change, but I guess the deeper draw causes more recoil and hence power loss? 

So it's HP1300 on the pallet pivots !

[nickelsilver]

Increasing the total lock, either by opening the banking or moving the stone out, means the balance spends more energy unlocking the escapement, thus the decrease in amplitude. Most of the time one ends up trying to reduce lock to gain amplitude though!

 

At a point excessive lock is detrimental to timing,  as the influence of the escapement on the balance motion becomes a fight between unlocking and delivering energy. Excessive lock also tends to affect the vertical amplitude more than horizontal. So always best to be close to "normal".

[praezis]

How is the vertical amplitude, in good relation to horizontal?
Then too strong spring or gears running more easy than expected.

But sometimes the balance pivot ends were polished ridiculously round. That will give high amplitude horizontal, but shows  poor amplitude vertical.

Frank

[mikepilk]

21 minutes ago, praezis said:

How is the vertical amplitude, in good relation to horizontal?
Then too strong spring or gears running more easy than expected.

But sometimes the balance pivot ends were polished ridiculously round. That will give high amplitude horizontal, but shows  poor amplitude vertical.

Frank

I reduced the wind to stop rebanking. DD at 290°, CR and CD both about 215°. That's a big difference - ties in with your theory !

It's a new staff, so pivots should be OK

I think I need to look at the sides of the balance jewels under high power on the microscope

Edited December 14, 2022 by mikepilk

[JohnR725]

1 hour ago, praezis said:

But sometimes the balance pivot ends were polished ridiculously round. That will give high amplitude horizontal, but shows  poor amplitude vertical.

The interesting lessons you learn in life. When I was a student I polished my pivots because we're supposed to reduce friction. Then with my running watch over to the timing machine in the days of paper tape no digital amplitude. The paper tape machine every time it printed made a nice clicking sound you could hear it all across the room. Which means if you did something interesting like polished your pivots insanely round the watch would make interesting galloping sound on the timing machine and everyone would know what you did. Nobody said anything but. That I learned how pivots are supposed to be more flat and the problem went away. So one of those interesting lessons of reducing friction is good but not on the end of the pivots we have to have the equivalent of the same friction no matter what position the balance wheels in so the end of the pivot cannot be polished nice and round.

[Malocchio]

Those pins can bend when cleaned manually with short and stiff brush. I did this once. I was too used to cleaning a mainplate with a pallet bridge and no separate pins.

[mikepilk]

Trying determine the cause of such a big difference between horizontal and vertical positions.

The pivots are good (new staff), nothing is fouling, the balance is reasonably balanced, and the regulator pins are not too open. So it must be the balance jewels (?)

I had to replace the top jewel as it was broken. I found one in the selection of jewels I bought from ebay* which fitted nicely. I didn't look closely enough before I fitted it, as  under high magnification I can see it is not totally smooth around the circumference. I guess that's enough to kill the amplitude ? (And I hadn't noticed the chip on the edge).(* I only paid £10 for the watch, and 3 hole jewels from Cousins are £18)   

 

 

[VWatchie]

2 hours ago, mikepilk said:

I can see it is not totally smooth around the circumference. I guess that's enough to kill the amplitude ?

I don't know but like you, I'd suspect it as well. If you can find a better one in your collection I think it would be worth a try.

2 hours ago, mikepilk said:

I only paid £10 for the watch, and 3 hole jewels from Cousins are £18

Having paid so little for the movement perhaps a £6 jewel would be worth it?! You'll keep the rest of the jewels in your jewel box for future use, so they won't go to waste.

[mikepilk]

2 hours ago, VWatchie said:

I don't know but like you, I'd suspect it as well. If you can find a better one in your collection I think it would be worth a try.

Having paid so little for the movement perhaps a £6 jewel would be worth it?! You'll keep the rest of the jewels in your jewel box for future use, so they won't go to waste.

I found another jewel which looks OK - it takes some searching through a pile of jewels to find one with the correct diameter and hole size. (Easier than searching a pile of stems for a match!)

It will have to do, as Cousins don't stock the size I need - 0.10 x 0.90 mm (as best as I can measure).

The hole jewels fitted have parallel hole sides, not the 'olive' shaped holes as in the Seitz jewels. That must have quite an effect on amplitude with the watch vertical.

[VWatchie]

17 hours ago, mikepilk said:

it takes some searching through a pile of jewels to find one with the correct diameter and hole size

In the pictures you posted you get really close. Is that through a stereo microscope camera? I've been looking at Cousins' offerings but it's quite an investment.

[mikepilk]

15 minutes ago, VWatchie said:

In the pictures you posted you get really close. Is that through a stereo microscope camera? I've been looking at Cousins' offerings but it's quite an investment.

Yes, I have a stereo Amscope with a camera mount. I bought a cheap Chinese camera (£50) which works pretty well.

[mikepilk]

When I said "the pivots are good as it's a new staff" - that was the assumption without a close inspection.

I was being a bit naïve assuming that !  Under higher magnification I can see that one pivot has been parted off and not rounded - there's a little nipple on the end. Also there's some scoring on one side of a pivot. 

That should explain the high amplitude flat, and poor amplitude vertical.

(See if I can polish on the Jacot tool without breaking a pivot  )

[nickelsilver]

Yes, that looks terrible! The ends should be like the image, that would be the max "roundness" I would do when redressing or making a staff.

Edited December 17, 2022 by nickelsilver

[clockboy]

The problem now might be to re shape the end of the staff it could now be a touch to short. 

[mikepilk]

The other end looks fine. I guess the moral is, don't assume that new parts are perfect.

[JohnR725]

6 hours ago, mikepilk said:

don't assume that new parts are perfect

Probably the majority a time new parts are just fine. But sooner or later there has to be one that fell through the cracks. My favorite over the years have been brand-new stems in this particular case they had crowns already attached. So in other words accompany cut of the length and attach the crown and no square. I think there was one that had a three sided square.

6 hours ago, nickelsilver said:

The ends should be like the image, that would be the max "roundness" I would do when redressing or making a staff.

Here's an image showing how you're supposed to make the end.

[praezis]

10 hours ago, JohnR725 said:

Here's an image showing how you're supposed to make the end

Another one of those great Jedritzki drawings.

Frank