Zenith

Ophiuchus
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Well...

if you're that interested in something that would bore anyone but me...

It's clear that the indices are friction fit to the dials very precisely- their tolerance on the 2 small
pins that locate them to the dial are marked (0, -0.02), meaning the shafts must be 0.25 mm, and
no bigger, but may be smaller than that by 0.02 mm. That is the distance of minimum endshake
on most balance staffs, for example. A small amount, but of course, there are smaller tolerances
in watchmaking.

Jewels must be made completely concentric and are toleranced often in the 0.001 mm range,
but this is expected given that they are fit to holes through fiction fitting, and 0.01 mm is required
in your mainplates for this. Tolerances in 0.001 range assure a relative consistency in fit for
mass produced jewels.

What is interesting is the dial indice shafts have such a small size, 0.25 mm, and must protrude
exactly 90 degrees from the indice, perfectly parallel, despite the print calling out for areas on
sides needing diamond polishing. Just holding those indices requires grabbing them by those
pins, and the slightest overpressure would distort them, making fitting impossible.

That's what impresses me so much. I cannot tell if the pins are machined in one block with the
indice, or are fitted into them. Either way, it would be difficult to image keeping the polish and
pin fit consistent considering all this. Throw in electroplating adding material over these, and
you really have to know exactly how long to leave parts in a bath, before the pins get too big,
and won't fit into the dials.

There is a LOT going on here- more than I probably realize. Special jigs and clamping pressures
would be just the start of keeping the dimensional tolerances called for. I imagine they have a
special department just for jig and machine maintainance- the slightest wear on the equipment
would mean distorted pins, bad polish, and bad fit, especially for so many indices for so many brands.

To even make that 0.38 mm square bottomed channel in the Zenith indices must require specialized
micro endmills. Special tooling suppliers with special tooling to make said special endmills would
be needed, tooling not normally commercially available.

Really a deep and inside look at something I never expected companies to allow outsiders to see.

Bravo for bringing us this.

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