Balance staff installation

[Sandy13]

This was my first attempt at replacing a balance staff. I followed instructions from  Mark's course and Kalle's videos . I used A and B stakes from my C&E set.

The hub disintegrated, did I tap too hard or did I choose the wrong size stakes, did the hub have a manufacturing defect, it was NOS for Omega  330 series.

Any suggestions would be welcome

Thanks in advance and cheers

[nickelsilver]

I don't know what size those stakes are, but I can see from the last photo that the rivet is still untouched. So yes, you hit too hard, and also had the wrong size punches (stakes are what go underneath). You want a convex punch that just fits over the hairspring diameter, thus against the rivet, then a flat faced punch with the same hole size. Tap tap tap tap tap tap tap round face, turn the balance a few degrees and punch as well in the opposite direction every few taps to even out any irregularities, check that it has spread a bit, then tap tap tap tap tap tap tap flat face to flatten it (turning as before). The roller table diameter should be in a hole in the staking tool die plate that lets it fit just freely, not tight but not flopping around, so the hub is supported on its flat surface. Obviously align the die plate well with the centering punch once you've chosen the hole.

 

If the balance is a light friction fit on the staff (ideal), then you would want a punch like you used to seat it, with finger pressure, no tapping.

 

Here's an image from lesson 15 of the Chicago School of Watchmaking course. It's easily found online in PDF format (I just grabbed this from here and it seems clean). Shows the fit of the concave punch, flat will be the same, also the fit in the die plate of the tool.

 

Remember this is a really small piece of heat treated steel, not a roofing nail . Also, just as reading about a subject always benefits from visual demonstration, visual demonstration will always benefit from some well written and illustrated reading.

 

 

Edited August 14, 2022 by nickelsilver

[VWatchie]

42 minutes ago, Sandy13 said:

This was my first attempt at replacing a balance staff.

Here are some additional first-class illustrations by member @HSL.

When I did this the first time, most of my information came from the video "Fitting a new balance staff to a vintage 1940s cyma www military watch. Repair series" and "How to fit a new balance staff to a vintage Rolex watch. Watch repair tutorials" and the above thread that I linked to. I'm sure there were more posts on WRT that I drew information from which I'm sure you'll find if you Google it (site:watchrepairtalk.com balance staff replacement).

1 hour ago, Sandy13 said:

I followed instructions from  Mark's course and Kalle's videos .

Now, this makes me curious. I've taken the first three courses on watchfix.com, but I can't recall any video demonstrating how to replace a balance staff. I only remember Mark showing how to remove the roller and the collet. Is this in the "LEVEL 5 Servicing Chronograph Watches"? 

Anyway, best of luck on your next attempt. Practice makes perfect!

[Sandy13]

Thanks to all for spending the time on your answers. I will trying again with some scrap movements.

VWatchie, I stand corrected on Mark's course, likely I mixed up presentations from Kalle Slaap on Chronoglide.