will go… step 8 – Details, more Details.
In the last installment I got carried away with my case work and forgot to show how the movement has turned out, the part of which I am most proud of right now. Here is the first picture of the movement back from rhodium plating. It takes my breath away, and you?
Look at how the jewels just jump out at you sitting as they are now in mirror polished recesses. The beveling accentuates the form of the plates. Gives them depth, soul and a heart. I am convinced. I had always thought that this Swiss infatuation with perfect finishing was just superficial prettiness. It is more. It is more than just knowing the amount of time that some dedicated craftsman spent to do the work. It adds light and form. The movement becomes more than a tiny machine. The reflections on the bridges form the fixed stars that make the framework in which the wheels and pinions, the planets, make their slow march forward. Each at its own rate, following the laws of the heavens. I find the transformation from a practical, good working movement to a beautifully finished timekeeping machine to be magical. Decide for yourself.
Here is a view of case and movement that will never be seen once the watch is assembled. The copper wire is doing the work of the dial to hold the motion works. And those are just some working hands stolen off a Swatch automatic that wasn’t watching out as it wondered across my workbench. I have been carrying the movement with me in a plastic movement holder modified for my movement. In my pocket for a couple of weeks now to see how it reacts to being carried around and shocks, etc., it doesn’t seem to be bothered much. It just keeps telling the time to about +3 to +5 seconds a day.
With that said, the case work continues. More polishing, getting ready for engraving. I realize that I was too quick with plating the movement, there is not a single indication on it, no name, number of jewels, nothing. But it is going to stay that way. For the case, however, I want to do it right. No engraving by machine at the jewelers, machine enforced uniformity. I choose hand engraving by an artisan. Can you believe that those letters could be done so perfectly without being guided by a machine? Well they can. Hand engraved on the case back, name, year and Nr.1. No, I didn’t even attempt to do that myself. Credit where credit is due. I would spend the rest of my life practicing and still not be that good. This is the work of Mr. Frédéric Digier of Neuchâtel. There is not a single machine tool in his atelier.
This watch will never be sold, but I had the assayers mark put on the case anyway.
With that done the case goes off to be anti-tarnish plated. Three layer plating to ensure good adhesion, white gold, palladium, rhodium. This is how the best silver jewellery is treated too.
It is now time to worry about the different steel pieces of the setting mechanism. I certainly can’t leave them looking like this first picture below, for example. I used lapping film down to 1u to get the pieces looking like this second picture:
I know you are all wrinkling your collective noses at those screw heads and ugly messed up screw slots. Rest assured that at the final assembly those screws will all be replaced with pristine new ones.
Now back to the case, I still don’t have a crown. From my CAD design I again had a model made by stereo lithography and had it cast in silver. Below the model and the casting can be seen along with the casting chucked up in the lathe to be cleaned up. This is to be a sort of bas-relief crown. The crescent moons to be polished and the background to remain rough.
An important property of the crown is to keep dust and water out of the case. To this end they are equipped with an o-ring that turns on the tube installed in the case. In order to give myself a chance for error I made the o-ring carrier in the crown as a sleeve in brass that I will press into the crown. Although or maybe because it is very soft, silver is not that easy to work. It has a tendency to tear instead of cutting, which can be seen on the edges of the crescents above. It is also hard on drill bits. I broke a bit when drilling the whole for the stem, but it dissolved out pretty easily in an acid solution of jeweller’s pickle. When I thread that hole I will be watching very carefully to not break the tap. I will break one tap on purpose ‘though. As the friction between the flat end of the stem and the bottom of the hole is a non-negligible portion of the force preventing the crown from unscrewing I will break the pointed end off of a tap and grind it flat in order to make threads down to the bottom of the hole.
Finished, polished and rhodium plated the crown looks really good (IMHO). I have not cut the stem to length yet as I haven’t finished the pieces that position the movement in the case.
Now I really only have the hands and the dial left to finish. The hands are already well along towards being finished. They need only a little final polishing and to be blued.
I figured that considering the difference in thickness between the middle and the edges of my hands it would be better to blue the hands in a temperature controlled oven than over a flame. So I tried bluing several pieces of scrap to find the correct temperature and found the perfect color at 318°. (It looks to me like the thermometer on this oven has to be off by about 18°) But when I tried putting the hands in for 10 minutes at this temperature they came out uneven, spotty and pale. Upping the temperature a bit seemed to make no difference. I didn’t think to take a picture, but why should I take a picture of what is not successful?
So then I tried bluing over an alcohol flame on a piece of brass to spread out the heat and lo and behold I have beautiful deep full colors. Only problem, the hands are not the same color.
As we can see the seconds hand is violet, was not warm enough, while the hours hand is light blue, it got too warm. I think that the minutes hand looks just right. So I will re-polish the seconds and hour hand and try again. It is difficult to assess the color while the piece is over the flame. If you get close for a good look you are in danger of scorching your eyebrows. In any case flame bluing seems to work much better than bluing in an oven. Maybe there is not enough convection in the oven to supply the oxygen needed. On the other hand the scrap pieces blued pretty well. Maybe the polishing somehow puts strains in the surface layer that affects the oxidation. I don’t have the answer.
I have had the crystals made, fitted and glued into the case. I didn’t do this work myself. To reduce the costs I decided to go for tempered mineral glass parts. A simple flat round sapphire crystal is not expensive, choose any other shape and the cost explodes. Making one piece in mineral glass is not dirt-cheap either, but the costs are reasonable. Even a slightly curved front surface is payable. I do not like flat crystals, they have straight-line reflections and give the watch a hard and sterile face, I think. On the other hand a highly rounded surface would not look good with the case design I have. So I had a crystal made that is very, very slightly curved. Just enough so that the reflections are not straight and hard. Perfect.
problems will be reduced to trying to decide what leather and color to pick
for the strap. First I must finish the hands and the dial ‘though. With two long weekends coming up, I hope I
will be done soon!
Copyright © 2006 Donald W. Corson