7750 incabloc stones

[matabog]

Hello!

I am servicing my first 7750 (thank you Mark for the YT videos and Lawson for the Disassembly/Assembly walk-through).

The movement is not new - let's say it has an obscure unknown history  It appears to be a genuine swiss 7750, but with a lower grade finish (very low...)

When putting back the balance stones I noticed that there were two sizes (two pairs, because the cap stones fit the hole jewel settings). I put the smaller stone and hole-jewel on the mainplate and the larger ones on the balance cock. I tried to but the larger setting on the mainplate but it didn't fit quite right. I believe the springs are the same size - its just the stones that differ a bit (aprox 0.1mm) 

 

So my question is: did any of you stumbled upon the same issue? Is it normal for a 7750 to have two different stone sizes?

Thank you!

Bogdan

[oldhippy]

The best advice I can give you. When taking apart anything with end stones always make sure you do not mix them up as some can be different in many ways.

[mikepilk]

If you look here http://www.incabloc.ch/en/pieces_rechanges.php you can find this page, which does show the upper and lower cap jewels are different. As oldhippy advises, always keep them separate when cleaning !

 

[Tiktok]

Generally speaking on most(if not all) eta calibres if the balance endstones are different sizes it is normally the balance cock that is larger than the main plate side, but as already said always make a mental note or write it down, even draw a picture if need be so you don't get them mixed up.

The only reason I can think for them making the jewels different sizes is maybe cost, putting the bigger jewel on show from the case back side and hiding the smaller jewel setting under the dial.

 

[matabog]

Thank you for your answers! I guess I was a bit lucky too. It was a 50/50 chance to mix them, and if wouldn't have mixed them, I am sure I would have picked wrong in the next 50/50 game of putting them correctly in the mainplate and balance cock.

I gues the way to go is to check for different diameters when you dismantle the movement and to make note of the correct way.

B

Edited January 11, 2018 by matabog

[mikepilk]

2 hours ago, matabog said:

Thank you for your answers! I guess I was a bit lucky too. It was a 50/50 chance to mix them, and if wouldn't have mixed them, I am sure I would have picked wrong in the next 50/50 game of putting them correctly in the mainplate and balance cock.

I gues the way to go is to check for different diameters when you dismantle the movement and to make note of the correct way.

B

The correct way is to keep them separate when you dismantle and clean. I use an old contact lens case with compartments labelled top and bottom.