Thanks, Bent!
To complete the Fusee Assembly, I needed two gears – the Great Wheel and the Maintaining Ratchet. That’s why the gear side adventure was done at this point in the program. And with those complete, I can continue on with a half dozen other small parts that need to be made.
First is the Fusee Click. This was made from W-1 tool steel. I plan to harden it eventually, though I haven’t done that yet (note to self). This part was mostly shaped on the 2” belt sander and with filing.
Next was the Fusee Click Spring. I made this from tool steel also. John doesn’t provide much information on how he made these parts, so this is my method.
I marked it out on the edge of a piece of 1/8” W-1 bar.
Then milled down the long skinny part.
I shaped the rounded part on the belt sander and files, then put it back in the mill to thin it down some on each side so that it would fit easily inside the cavity on the back of the fusee.
Next, I used a slitting saw to slice off the full spring.
This part felt super brittle to me. I don’t know that it was, but I was worried that if I tried to shape this, it would snap. So heated it up with the torch to do my bending work. This seemed to work OK. I heated it several times. I really didn’t want it to break!
Here I’m fitting it in place to see how long the spring actually needs to be. You can see the little black Sharpie mark above the click showing the desired length.
After cutting it to length and a little more bending work, here it is in place against the click. Note that I’ve removed the ratchet from the fusee for all this fitting work because the fusee ratchet, fusee click and spring are all actually behind the maintaining ratchet when in place.
And now, I had to screw the ratchet back into the backside of the fusee, and somehow get the click and spring all engaged in the right place while it is hidden behind the maintaining ratchet. It took some doing, but eventually, I got there:
Here’s a short video of me clicking the Fusee. How cool is that?
I made a couple of little pins and the Maintaining Spring. The pins were made from stainless steel, and the spring from 1/16” square W-1. This time I just bent the W-1 and it worked quite well. I didn’t bother to heat it up or anything. Maybe I didn’t need to do that before either. The pins are shown already connected to the Maintaining Ratchet (left side) and the Great Wheel (right side) with the spring in the middle.
This is how the spring sits in the Great Wheel. One end hooks around the pin on the left, and the top end will engage with the pin on the Maintaining ratchet.
And here it is assembled. You can kind of see the spring inside there, touching the pin at the top. The pin is attached to the Maintaining Ratchet inside and pushes against the spring.
Here’s my feeble attempt to explain how this all works: When the clock is just running, the fusee turns the Maintaining ratchet through the Fusee Ratchet (the inner click and ratchet we did first), and the pin in the Maintaining Ratchet pushes against the Maintaining Spring, imparting torque to the Great Wheel. But when someone starts to wind the clock, the fusee will turn in the opposite direction and no longer impart power to the Maintaining Wheel. This would normally allow the whole drive train to go slack, but there is another click (that hasn’t been made yet) that will engage and keep the Maintaining Ratchet from turning backward with the Fusee as it is being wound. And since the Maintaining Ratchet won't move, the pin holding the top end of the spring will stay in place, allowing the spring to continue to provide power to the Great Wheel. At least for a short while – until the spring doesn’t have enough torque to continue to operate things anyway. But it only has to provide power long enough for someone to make a ½ wind or so. Because then they’ll have to let go of the winding key to turn their wrist back. When this happens, the fusee will reengage and supply power to the spring again until the next wind.
Here's another short video of me playing with the Spring connection to the Great Wheel:
Next, I’ll make a slip washer that will lock the whole Fusee Assembly together.
Oh yeah, and heat treat the click.
I think I may try heat treating the springs, too. Harden them and then temper till they are blue? That’s the right way to temper a spring, right?
Or should I just leave the springs alone, untreated? Thoughts?
Kim
