Gear polishing part 2

 

A little refresher in case you have forgotten part 1: The technical hurdle of polishing the teeth of the gears we make seems insurmountable. No one is around to help, our cries of anguish fall on deaf Swiss ears, the darkness approaches as we realise that our NH3 project cannot progress, alone in the void of watchmaking purgatory, we wait.... Enter James, our new toolmaker. A knight in shining... engineering overalls comes to our rescue. A micrometre in one hand, safety glasses in the other, he stands in front of the milling machine smiling - as if the impending doom of a failed project isn't looming. I explain the situation. "James, we can't polish the teeth of this gear, we can't do it manually, we can't buy a machine that will help us, and I don't know who to ask to help!" That's more or less as much as I said. A week of research: looking at photos of antique machines on the internet, scrolling through video tours of Swiss workshops frame by frame, looking through blogs and books and horological bibles. Even the great Daniels is remarkably silent about this dark art (read, he kept the secret to himself). James emerges with a concept, an idea. "Let's build this machine ourselves!" I've always wanted NHW to do this - building machines for individual, specialised tasks that would make the process of manufacturing a part easier. All the famous ateliers, from Pratt to Breguet, were littered with small desktop sized machines that helped their users execute one task and one task only, but to perfection. Some machines would only drill accurate holes, others would create a snailing pattern on a barrel lid, others would burnish the surface of a pinion to a mirror. In our case James proposed a modern take on a 1940's machine called a Prata Type 11. This machine would handle the polishing of the teeth with the ancient method of a split wooden disk that auto-indexes the gear whilst polishing the flanks with a fine abrasive paste. I felt relieved! Having a way forward meant that we could progress and make not only this specific set of parts, the ratchet and crown wheel for the NH3, but also all hardened steel gears for futures watches. But, the road would not be easy.... In fact it would only get harder. Stay tuned for Part 3. Josh