Chapter 7: The Click, Spring, etc.June 22, 2005
This chapter has a wide variety of stuff in it, and because I needed to test the teeth on my great wheel I did it all in an odd order. First up was the center pinion. Since pinion cutters are so expensive, this clock uses lantern pinions. I made a spade drill for the pin holes out of a piece of the music wire used for the pins, and it worked fairly well despite being a little uneven. Here are pictures of the brass pinion bobbin, and the completed pinion with steel pins.
Once the pinion was completed, I was finally able to try out my depthing tool and test the teeth on the great wheel. Here's a shot of the depthing tool, with the great wheel and center pinion mounted on it. Luckily, the teeth seemed to mesh fairly smoothly. I don't really know what to look for, but my uneducated guess is that the great wheel will work just fine, so I'm going to move ahead with it and see how it goes. There is one sticky spot where the teeth are slightly too far apart, but since this is the first gear in the train, I'm hoping it won't be enough to stop the clock.
Once I'd decided to go ahead with the great wheel, I could finish the barrel assembly. I cut the click out of a piece of tool steel sheet, and made a brass bushing for the click screw so that the click can swing freely. The book calls for brass spring stock for the click spring, but I couldn't find it anywhere. I made this one out of the same leaded brass used for the rest of the clock, and hammered it for a while to harden it. It seems to work fine so far - it will be interesting to see if it loses its springiness over time. The barrel assembly is the first part of the clock with moving parts, so it was great to see it working. The movement of the great wheel around the barrel arbor is very smooth, and there's almost no perceptible play. The click and ratchet wheel work beautifully together. Here are a couple of shots of the completed assembly.
The rest of this chapter involves cutting the center and third wheels, and making the third and escape pinions. Here are pictures of the wheels before and after spoking, and one of the pinions before sanding the pins flush with the bobbin. I actually had to make the 80 tooth wheel twice... I dropped the first one onto the concrete floor of our garage when it was almost finished, and the bent the teeth. I really ought to put down some thin carpeting or something, but I haven't gotten around to it yet. These wheels were cut in place on the lathe, using the adapter block I made. The index plate makes it very easy to cut all the teeth, and there is no problem with the teeth being off center as on the great wheel. Unfortunately, the milling setup is heavy and hangs off the front of the lathe, which isn't rigid enough properly support it. It's very hard to move unless I support the mill headstock, and then the cutter moves slightly. So... the new setup is better, but unless I'm careful can still lead to slightly unevenly spaced teeth. It's hard to judge how much error this introduces... so actually, the new setup might not be better. :-/