Credits: Article and images by Elizabeth Doerr @ Quill & Pad. See the original article here - https://quillandpad.com/2024/03/05/rick-hale-wooden-clocks-designed-and-built-as-if-by-john-harrison-except-today-and-in-the-usa-beautiful-photos-videos/
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Other modern examples of the grasshopper escapement are fitted to the Burgess Clock B and Parmigiani’s Senfine concept watch, though the latter has not yet gone into serial production.
The grasshopper escapement earns its name by virtue of its motion, and while it is precise when running properly, it is hard to adjust and get to that point. The single pivot used to hold Hale’s version means that it is a “flying” escapement, allowing a clearer view of its motion. That’s an unusual and challenging regulator for an autodidact to choose to use.
Hale agreed with me, “It definitely felt like going from 0 to 100 a little too quickly in the beginning, but the fact was with wood I really had to avoid sliding friction in every way I could – which instantly ruled out an anchor, recoil, or any of the more basic escapements.”
How Hale came across the grasshopper was almost as unusual: perusing a book that wasn’t focused on Harrison, he saw something about Harrison’s maintaining power and looked him up. “When I saw the grasshopper I instantly knew [it was the right thing for me]: the fact that it just touches the teeth instead of sliding against them. Even though it takes more time and there are more pieces in things, once I came up with a good design for it, it was just the right thing.”
Rick Hale’s KL1 in detail
In essence, this clock functions like any other with a conventional gear train and pendulum, though Hale’s is slightly reworked for use with wood. He uses brass in the center of his wooden gears to provide the teeth with a little more strength.
Even the springs are made of wood; he removes a tiny bit of material at a time until he gets just the right flex. “As soon as people hear ‘wooden springs,’ their faces go white and some wait [to respond], thinking there’s no way that’s a good idea,” Hale laughed.
“But because it’s distributed among four springs you get very little force being used for each of them, and it gives you just enough flex to provide maintaining power. The idea is when you’re winding you don’t really take away the power from the clock, so you keep the pendulum going.”
Then there is how Hale makes his gears. “If you were to try to just make a gear out of one piece of wood, obviously it would warp and do all kinds of crazy stuff, so my method of construction constitutes four staves going out and then four fellows around the edge, so there are eight pieces of wood.”
Hale also constructs them that way because of the wood’s grain. “It really wants to breathe across the grain, and this layout allows that. What you get with changes in temperature instead of warping is a very gentle, uniform material, like the diameter wants to grow or shrink rather than crazy things happening.”
The way I understood it is that by using this construction method, the wood acts more like metal than wood within the movement.
“I’ve kept these test gears around for four years now just to see if they would move or do anything weird, and they’ve stayed very flat and true. So I feel good about my process.”
But, he explained, the one shortcoming with this method is that because of the grain, not all the teeth will have the same amount of strength. To avoid having some teeth be stronger than others, he uses a process that takes a lot more time and effort: he cuts each little groove and makes each little tooth and then mounts them one by one.
While this process is painstaking, one advantage is being able to polish the faces of the teeth to his desired degree before inserting the teeth. It also allows him to make the teeth thinner.
“It’s the nerdiest thing I’ve ever done probably: I took the way that Harrison laid out his gears and rollers and made myself something like a calculator so that any time I need to come up with a new gear set, instead of trying to figure everything out and spend a day laying it all out, the calculator tells me. If I want to make this gear have 120 teeth and be this diameter, then what diameter does my pinion need to be and how big do the rollers have to be and all that. It makes it a little bit more automatic.
“The upshot of that is any time my clocks have a gear set, it is true to the geometry that Harrison used. That’s something I’ve done in a way to separate my work from other stuff that’s out there. Because even in metal I don’t think there’s anyone really using the chordal pitch gearing layout. Even in the replicas I’ve seen of H1 or H2 people generally use more modern tooth profiles.”
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Credits: Article and images by Elizabeth Doerr @ Quill & Pad. See the original article here - https://quillandpad.com/2024/03/05/rick-hale-wooden-clocks-designed-and-built-as-if-by-john-harrison-except-today-and-in-the-usa-beautiful-photos-videos/