Week 31 Feb. 21-26, 2011

Last week I spent most of my time working on hairsprings. I hadn't touched any since before the christmas break so it had been a while. But that was the last part to get the W-01 running so I had to get started.

The first part was to attach the inner part of the spring to a collet. Then you center and flatten the spring to the collet. After that you use the vibration tool to find the vibrating point. It looks like a complicated tool but it's not too crazy. The idea is to pinch the spring at the correct length to make your balance wheel oscillate at the same speed as one of a known frequency. This will ensure your balance will be the right frequency to match the gear ratios of the rest of the watch. In the picture you can see an 18,000 on the side which corresponds to 18,000 vibrations per hour.

Finding the vibrating point is also used to see where you need the spring to come out of the collet (for flat hairsprings). This is because the rate at lower amplitudes changes depending on the angle of the colleting point to the vibrating point. Hopefully this makes sense. If not maybe I should work on that, might have to explain this on a test at some point...

Here you can see the wheels are meant to have the spokes aligned so you can see by eye if the wheels are oscillating together.

As I said before, the W-01 will have a Breguet overcoil. So after I was done finding the vibrating point, I was ready to bend the overcoil. The idea is to make two 35-45° bends to make the last coil higher than the rest. Then you bend the spring into a certain shape according to the diameter you want at the pinning point (end of spring where the clamp pinches it).

I showed a picture of the different overcoil shapes last week, here it is again. I originally picked the one in red, but I had to use the one in green after finding the vibrating point to be much longer than before because of the heavy balance wheel. As you can see, the lower the number, the closer to center C becomes. I had already made the clamp so I had to follow the pattern that matched the diameter of the clamp.

The overcoil was not really that difficult to bend for me. I built a little tool to help me bend the overcoil part of the spring that worked really good. It was just a really thin plate of brass that I could slide the majority of the coil under, and then just work on the overcoil part. It helped keep it much more flat and straight. But it still did take about 3-4 hours to get it looking nice and following the correct shape. You can see in the photos the last part of the spring seems to rise up a bit so I'll have to see what is causing that.

Here you can see the two bends in the spring that raise the last coil up. Then from there it goes overtop and around to where the clamp is. 

And here you can see where the clamp pinches the spring. That is the exact point I want the vibrating point to be. It will take some time and skill to get it perfect, because this is what sets the rate of the watch. even a few hundredths of a millimeter to the left or right could make the watch go 10-20 seconds faster or slower. 

There is also some extra spring sticking out on the right side that I will trim off later when I know the exact location. 

So after putting the spring in the clamp the watch was ready for its first oscillation! I just wanted to see it working so I didn't clean and oil everything, but it still worked fine on the first try. It was very satisfying to see it finally come to life. It was also cool to see the overcoil as I hadn't really looked at one up close (even though we have worked on Rolex watches with overcoils, I just never really looked at it). 

Next thing I did was clean everything to see if I had a decent amplitude. We had to make the balance staff so you never know if things are going to work great on the first try. I had 290° amplitude in the horizontal position so that was a great start. The vertical position wasn't that great (215°) but there are a lot of reasons as to why. I now have to start fine tuning to get the results I am looking for. But here's a quick video of the watch actually running!

One other thing to mention about the overcoil. f you watch the video you can see how the spring expands and contracts evenly around the entire spring. This is because the overcoil places the center of gravity in the center of the balance. On a flat spring the center of gravity is not in the center of the balance so the spring will expand and contract a different amount in different spots. This is one of the benefits of the overcoil.

I am also working on getting the AMS1 running. It will have a flat hairspring so I will have more examples of that later. But I put in the eccentric banking pins and I think they look cool. Now I still have to adjust them and also make a spring for that balance. And I have to figure out a way to make some regulating pins. They are extremely small so it's not going to be fun...