Another Clock

[jteneyck]

I thought I'd had enough clock making for a while, but then I found the design for this one from a guy in Germany and just had to build it.



It's a twin compound pendulum design, a tribute by the designer to John Harrison, the man who invented the first clock to keep accurate time at sea.  My last clock employed a grasshopper escapement, as does this one, which are known for being very accurate timekeepers and also quiet, a requirement to keep my wife happy.  

I make my own plywood for clocks.  That allows me to make any thickness needed in any species I want.  This clock is made from maple and mahogany.  I added a center ply of mahogany in the maple plywood and maple in some of the mahogany plywood, as you can see here.



To appreciate the clock best you just have to watch it run:  

Video

John

[MarkSLSmith]

I thought I'd had enough clock making for a while, but then I found the design for this one from a guy in Germany and just had to build it.



It's a twin compound pendulum design, a tribute by the designer to John Harrison, the man who invented the first clock to keep accurate time at sea.  My last clock employed a grasshopper escapement, as does this one, which are known for being very accurate timekeepers and also quiet, a requirement to keep my wife happy.  

I make my own plywood for clocks.  That allows me to make any thickness needed in any species I want.  This clock is made from maple and mahogany.  I added a center ply of mahogany in the maple plywood and maple in some of the mahogany plywood, as you can see here.



To appreciate the clock best you just have to watch it run:  

Video

John

Too cool!!

[MstrCarpenter]

That's awesome! Great work. It would be almost unbelievable to see this in the Woodworking Hand Tools (only) forum. I'm sure there are some members here that could do it. I probably couldn't build it even if all the parts were pre-cut.

[stav]

That is very cool.

[Bill Holt]

All the movement is mesmerizing!!!

Thank you for the video.

[jteneyck]

That's awesome! Great work. It would be almost unbelievable to see this in the Woodworking Hand Tools (only) forum. I'm sure there are some members here that could do it. I probably couldn't build it even if all the parts were pre-cut.

Thanks.  

I know there are people capable of cutting those parts by hand, but I'm not going to take that challenge.  It's not an easy task to get one of these clocks to run even using a CNC to cut the wheels.  It's an exercise in patience and working as precisely as possible with each step.  That big weight of just about 6 lbs you see hanging below the clock is diminished to only a few grams of force by the time it gets up to the escape wheel that keeps the pendulums swinging.  Just a little bit friction is enough to cause it to stop. There is a surprising amount of handwork necessary in fabricating the other parts and in assembling the clock, so I have that in common with the hand tool folks.  I also made those brass disks you see in the ends of the fobs with a little lathe I have and never use much but am happy to have for those times it's needed.  Those inserts are made from 1" brass rod, cut to length, and then relieved on the back side until they all weighed exactly the same.  With no X-axis scale on the lathe, that proved a bit of a challenge.  But now that I think about it, I could have taped a scale on the way somehow.  Next time.  

John

[FrankAtl]

I really like this one! As someone else said, it's mesmerizing. Well done!

[Tapper]

Beautiful work as always, John! What a unique looking piece - has to be mesmerizing! Tell us a little more about that lathe - metalworking?

Doug

[jteneyck]

Beautiful work as always, John! What a unique looking piece - has to be mesmerizing! Tell us a little more about that lathe - metalworking?

Doug

Thanks very much, Doug.  I really enjoy how this clock works so when I saw it, I knew I wanted to build one. 

The metal working was pretty simple.  I took a 1" brass rod and rough cut the lengths I needed with a hacksaw.  After I chucked it in the lathe, I faced off one side and left the little nub in the center for some visual interest.  I flipped it around, faced the other side to final length, and then hollowed it out until they each weighed 38 gms.  I did that first by rough measurement of the wall thickness and then crept up on the exact weight by taking a pass, weighing it, taking another pass, repeat.  I had to do it that way since I had no easy way of knowing the exact depth I was cutting to.  Had I known and been able to control the exact depth, I would have been able to turn them to some specific ID with pretty good assurance the final weight would be correct.  Maybe that actually is possible with the lathe I have, but I use it so infrequently and never had any real training, so it's not obvious if it is.  

John

[professore]

Fantastic piece of work.  I can only imagine the patience it took to get it right.

Frtank S in IA