A Clock of my own design

[jteneyck]

I have gone down the rabbit hole, an obsession my wife would say, to build a clock of my own design.  My wife also hates the tick-tock of typical mechanical clocks with pendulums, or similar timing mechanisms, so my primary objective was that whatever I build had to be very quiet.  During my investigations into different escapement mechanisms I found that one called the grasshopper is exceeding quiet.  It was developed by John Harrison, a brilliant English clock maker who developed the first clock that could keep time accurately at see, which solved the longitude problem that had plagued sailers since man started sailing across the open ocean.  Harrison started as a woodworker, so there's hope for the rest of us wood butchers.  

If you see a clock with a grasshopper movement you'll see it's very unique.  It's also not obvious how to design and make that movement.  Fortunately, Harrison wrote it down, more or less, and others have studied and interpreted his work so that us mortals can draw or calculate the key dimensions required for any particular size and number of teeth on the escape wheel.  I built a grasshopper movement and escape wheel just to see if my design actually worked.  I was amazed that it worked just as it's supposed to.



With that confidence boost, I set about to design the rest of the drive train of the clock.  I built a prototype, and then a second prototype to work out both the design and some technical challenges.  I had planned to use a typical weight drive and rewind system, but some what turned out to be unrelated problems, pushed me towards using an endless rope (remontoire, for those who might know about clocks) mechanism.  With the design I developed the remontoire weight drops nearly 12"/hour, so it would need to be rewound at least every 6 hours.  Well that's no good, so I incorporated an automatic rewind system that lifts the weight about once per hour.  This is done with a small motor, a relay, and two limit switches tripped by the weight, one to turn the motor on, the other to turn it off.  

I built the clock from walnut plywood that I made from shop sawn veneer.  The wheels are machined from cast acrylic and the pinions from cherry plywood.  The grasshopper itself was solid cherry.  Most parts were cut on my CNC, some several times to get them right.  Lots of handwork to fit shafts, bushings, alignment pins, and all manner of other pieces.  All in I must have somewhere around 300 hours in this, making it the longest woodworking related project ever.  

I used acrylic for the escape wheel because the one I made from plywood would always chip out on the tips of some of the teeth, and precise trips are key to the grasshopper working.  Here's what it looks like in acrylic, all 120 teeth.



The acrylic machines so beautifully that I decided to use it for all the wheels.  

Thanks for your patience.  Here's the clock. 







And here's a link to a video showing it running.  Video

What a great project.  And, yes, it's incredibly quiet, any background noise makes it silent.  

John

[KC]

No words.

Even 40 years ago when I had the patience of a newbie willing to figure things out that would've given me a headache!  Mad props, sir.

[2beast]

Wow, that’s awesome 
I can’t even wrap my head around building that!

[Gary G™]

Absolutely fantastic.

[FS7]

That might be the coolest thing I've ever seen on this site.

[jteneyck]

Thanks for the kind words everyone.  I bought the CNC to explore new avenues of woodworking, but also to keep my brain active and occupied.  Somewhere in the first year of owning it I saw plans for a clock on Etsy and bought them.  That started the obsession, especially when I could never get the clock to run for more than a day or two w/o stopping. 

Designing and building this clock definitely kept my brain occupied.  

John

[Tapper]

Beautiful work as always, John! Congrats on keeping the old synapses clicking!

Doug

[iublue]

Wow is about all I can say!

Kudos!

[DogwoodTales]

holy freakin' clock, batman. that's really kewl! Nicely done.

[hbmcc]

That's a remarkable design and beautiful rendition.

Two points:
I always wanted to build one of these, but it living on a couch under the cushions was definitely counter productive. Good to know you resolved that issue.

Second, now that I am older I've discovered impatience. I envy your patience.