Mechanical Clocks: A COVID Shelter-in-Place Story
I decided I should build a mechanical clock during a global pandemic, for a few reasons. First and foremost, because I am temporarily banned from building another boat by the Treaty of Survive Your First Year of Marriage. Second, because I can’t bake bread to save my life. And third, because I’m a 21st century-trained engineer with no freaking clue how clocks actually work, and that’s pretty pathetic, in my estimation.
I arrived at mechanical clocks circutitiously, having set off instead to learn more about maritime navigation, during the copious reading opportunity presented by threat of $1,000 citations for shelter-in-place violation. But it turns out, you can’t learn about navigation without learning about clocks. Indeed, both the 18th century solution to “The Longitude Problem”, as well as 20th century Global Positioning Systems, were both fundamentally just advancements in the clever placement of clocks. The accuracy to which you can know where you are is and has always been an exercise in timekeeping.
Who Cares?
Every Navy, ever.
There is probably nothing more terrifying than operating a warship, of any era, in a situation where your opponent can track their position and you cannot. If you’re relying on sextants, and suddenly a fog rolls in, your opponent with a magnetic compass has you dead to rights.
If you have to hug the shore for safety, how can you possibly hope to wage war with a civilization who can sail anywhere in open water with confidence?
There’s a good argument to be made that British naval supremacy in the 18-19th centuries, which hugely shaped our post-colonial world order, had more to do with their ability to know where they were at sea than anything else.
As with most technological development, it was these sorts of pugilistic realities that brought the brightest minds of the Industrial Revolution to bear on the problem of Longitude, much as their intellectual descendants would be conscribed to solving radar, decoding enigma machines, and detonating piles of uranium.
So I decided I wanted to learn how my engineering ancestors of the Enlightenment mastered maritime navigation (before computers and satellites), and what the hell this had to do with clocks — educate myself on how one actually works, and see if I was up to the task of building my own.
The Zybach Clock
Having learned my lesson the hard way last time, this time I decided, rather than design a thing I had no expertise in from scratch, I would instead follow someone else’s schematics and learn “the right way” first. Crazy.
I decided to attempt a wooden pendulum clock — partly because they’re beautiful (if it doesn’t work… it becomes wall art), and partly because I had some woodworking experience now, and tiny metal gears would probably be outside my abilities and tooling.
2020, setting aside “that whole virus thing”, is a pretty amazing time to be alive if you’re a DIY hobbyist. Within about three hours of committing to this decision, I had downloaded some mechanical clock schematics from an impressive kinetic sculptor for $40.
The schematics were in a digital format that many CNC routers can understand, and he included great assembly instructions, with all the extra hardware I’d have to purchase, along with copious tips for all the wood/metalworking techniques I’d need to master. Which, for me, would be a lot.
Why Clocks?
Unlike latitude, which is pretty easy to estimate from the angle the sun makes with the horizon at noon, longitude (by virtue of the Earth’s rotation) has no equally straightforward solution. Fascinatingly, most of the heavyweights of the time (Newton, Halley, etc) were off chasing the wrong solution. They were convinced it involved measuring angles between the moon, stars, horizon, and checking reference tables, as most of these sorts of things had been done before.
It wasn’t that they were wrong — you definitely can determine longitude by taking a few such measurements. There’s just two problems. First, you need to be able to measure angles much more accurately than for latitude… on a rocking ship, subject to those pesky clouds. And, even if you could take measurements accurately, you’d still need a huge reference table to tell you what those celestial angles meant for your longitude… for every date in the future.
As they eventually realized, computing these tables was pretty freaking hard by hand, even for them. Since the Sun, Earth, and Moon all tug at each other through gravity, figuring out where they’ll all be years from now turns out to be staggeringly difficult without computers— the now-famous “Three Body Problem” you may have heard of.
Meanwhile, an industrialist and clock maker in England by the name of John Harrison, with almost no formal education, was taking a different and significantly simpler approach. The Royal Navy was so obsessed with the Longitude problem that it posted a $20,000 reward ($2.9M today) for a successful technology demonstration, drawing the curiosity of every inventor of the time.
Harrison’s approach was not unique, and based on a much older observation: Since the earth rotates 360 degrees in 24 hours, that means it rotates 15 degrees longitude per hour. So, let’s say I set my clock to Greenwich time as I depart London, and sail for a week west across the Atlantic, toward the less socialist side of the pond. On the 7th day, I wait for the sun to peak (at noon), and then look at my watch, which shows 2pm in London. Ta-dah! I know that I am two hours west of London, aka 30 degrees of longitude! That was easy, all I needed was a good clock (marine chronometer)! Why the hell was Newton wasting his time with Three Body Problem?
Well because, if measuring lunar angles precisely was hard, then building a pendulum clock in 1714 that could oscillate faithfully in 10 foot swells was a freaking nightmare. Not to mention, salt air and metal gears.
But also, because engineering was such a middle-class endeavor. Intellectual gentlemen like Newton studied the motion of heavenly bodies; grease monkeys like Harrison and Watt hammered on steam pistons and gear trains. Socioeconomic blindspots hamper even the brightest bulbs.
Grease Monkeying with the Shaper Origin
After a few evenings of reading over schematics and reading up on clock history (Horology), it was time to get to work building my own mechanical clock. An unabashed Shaper fanboi, still anxiously awaiting his royalty check for shamelessly preaching their product for years, my choice of woodworking tools was a foregone conclusion.
The Zybach schematics uploaded to the tool, and I was off and cutting with modern computer-aided precision. Luckily, I had a bunch of leftover marine plywood from last year’s boat adventure to start with.
However, I quickly realized that marine plywood cuts like the gluey, rot-resistant miracle it is, and that “craft plywood” makes for much nicer, sharp-edged gear teeth. For the boat, nothing ever needed to be this intricate. Lesson learned, I switched to craft ply half way through, and hey — now I’ll have a cool two-toned clock like on the website.
Within a few weeks of quarantine evenings, I had basically all of the wooden parts cut — gears to work out the ratio between hour and minute hands, an escapement mechanism to generate “ticks” from pendulum swings, a winding wheel for the main counterweight, and a bunch of spacers and mounting parts.
It was time to start building sub-assemblies with all these parts, and some additional metal connectors, rods, and screws I’d need from a hardware store.
In part two of this blog post, I’ll dive into my clock assembly trials, tribulations, and learnings. I’ll also still need to finish the wood, and attempt to build and install a pendulum.
And if you’ve made it this far, you couldn’t have been completely bored by my take on the history of clocks and maritime navigation. So I’ll keep rambling about how it all unfolded to advance us to modern clock design too, I suppose.
