Baumgartner BFG 866 - Oiling cap jewels

[Jon]

Hi All,

I posted a while ago a walk through of the Baumgartner BFG 866 and wanted to add to it, especially as there is little out there to explain how to oil the cap jewels of a non shock proof watch.

 

This is the balance cock of the BFG 866 and as you can see it has a cap jewel held in place with two screws, screwed from underneath.

Some pull the hairspring out of the way to oil through the oil sink, but I find it safer to remove the hairspring, but also it is good practice to do so.

If the balance and hairspring is removed the shape of the hairspring is seen a lot easier and any manipulation can be done.

The hairspring may have to be taken off the balance if it isn't a simple tweak.

Removing the balance from the cock is quite simple

Measure the balance staff to find out how big it is, so when we make a tool to push the oil through to the cap jewel, we will know the correct size to make

We need to unscrew the cap jewel to clean it

Now we are going to hone an old oiler to fit through the hole in the oil sink that the balance staff pivot passes through

Be careful not to damage the pivot hole

Once the balance cock and setting has been cleaned thoroughly, we can then oil the cap jewel through the oil sink with Moebius 9010

If you are not sure you have oiled it enough, or your technique is correct, remove the cap jewel and have a look. 

Obviously before screwing back the cap jewel it will have to be cleaned properly again

This is a safer way than oiling whilst the hairspring is attached to the balance cock. It may take a while longer, but it is a lot safer!

It is also good practice in removing the balance and hairspring from the cock, but also checks the state of the hairspring, especially the uniformity of all the coils and how the hairspring is studded

onto the collet

The other cap jewel in the mainplate would be oiled in exactly the same fashion.

Trying to oil the cap jewels and then fixing them onto the setting isn't a good way to oil them, as the oil will probably be smeared when re-fitting them.

This is the way I teach my students to oil their non shockproof cap jewels

I Hope this helps someone else in the future.

More BFG 866 practicals to follow....

 

 

[VWatchie]

Just brilliant! 

Thank you!

[SparkyLB]

Very well explained.  Thank you for taking the time! 

[JohnR725]

somewhat hard to find because something has been lost in the translation? If you look at the comparison between the first link and the next two links you will grasp why I have that strange wording. So they make a tool specific for getting the oil to flow in its found at the first link. For unknown reasons the second two links have an incorrect description.

so the tool itself comes with super tiny tips perfect for getting the oil to flow. The only downfall is the tips are super tiny and they have a habit of breaking mysteriously. I no longer even have the tip on the handle I found that really helps to keep it from getting broken.

https://www.esslinger.com/watch-oil-inserters-tool-balance-jewel-oiler/

https://www.hswalsh.com/product/oiler-yellow-precision-incabloc-ho16

https://www.cousinsuk.com/product/oilers-3-in-1-incabloc-specialist

[Nucejoe]

Hi @jon In some jewel-less veriants, we face the fork pivots in metal hole which I have been oiling just because it is metal against metal. Never seen a lesson on that, would you elaborate on this, they didn't have advanced oils back then, dose the oil type make as much difference as it dose on jeweled forks?