Mechanical clocks

[KC]

Off topic post about watches crossed over to clocks, and I though I'd post up one of my most favorite projects.  I built this clock case/shelf (mesquite) sometime around 1998 I think.  Hermle movement from Woodcraft that I've done absolutely nothing to other than blowing the dust off a couple times when moving it.  It keeps good time, losing maybe a minute a week.  Built it specifically with the David Winter cottages in mind.  We've had it for so many years that I don't always notice the chime (hour count and half hour only), but every time I do it makes me happy... and reminds me to be grateful I have the ability to work wood, and thankful for the people I've 'known' because of that.  Wife mentioned the other day that I probably oughta show her how to wind it.  26 years and she's never done it.  


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[FrankAtl]

Great looking clock! Always enjoy looking at projects I completed many years ago that are still in use.

[Bill Holt]

Yes, that is a great looking clock.

[jteneyck]

That's a really nice look case you made, fits the movement very nicely.  A minute a week isn't bad, but I would think that mechanism could do better.  Have you ever tried adjusting it?  

And as long as we're talking about clocks, do you know what the purpose of that banjo is on the pendulum?  It's not for decoration, even though they are made to be decorative. 

John

[KC]

That's a really nice look case you made, fits the movement very nicely.  A minute a week isn't bad, but I would think that mechanism could do better.  Have you ever tried adjusting it?  

And as long as we're talking about clocks, do you know what the purpose of that banjo is on the pendulum?  It's not for decoration, even though they are made to be decorative. 

John

Yeah, I used to fiddle with that all the time, but it's so close now that I just leave it alone unless it gets bumped during one of the very rare dustings of the shelves.  Shoulda put a door on it.  

[jteneyck]

Yeah, I used to fiddle with that all the time, but it's so close now that I just leave it alone unless it gets bumped during one of the very rare dustings of the shelves.  Shoulda put a door on it.  

No guess on what the banjo does?

John

[KC]

No guess on what the banjo does?

John

Assumed you were talking about the bob adjustment to regulate the time (which is what I was talking about).

[jteneyck]

Assumed you were talking about the bob adjustment to regulate the time (which is what I was talking about).

I should have used the word "harp" instead of banjo.  It's the section of the pendulum with the thin rods that sits above the bob.  The ones made today may or may not actually be functional, but back when John Harrison first developed it its purpose was to compensate for changes in pendulum length due to temperature.  He used metals with opposing coefficients of thermal expansion to maintain the length of the pendulum to a near constant value.  I'm not sure if he or someone else also developed a means to compensate for changes in barometric pressure, which effects the density of air and, thus, the timing of the pendulum. 

A clock of Harrison's design was proven a few years ago to keep time within a few seconds over many months.  It is amazing to me that such an accurate time keeping piece was developed in the 16th century.  

John

[KC]

I should have used the word "harp" instead of banjo.  It's the section of the pendulum with the thin rods that sits above the bob.  The ones made today may or may not actually be functional, but back when John Harrison first developed it its purpose was to compensate for changes in pendulum length due to temperature.  He used metals with opposing coefficients of thermal expansion to maintain the length of the pendulum to a near constant value.  I'm not sure if he or someone else also developed a means to compensate for changes in barometric pressure, which effects the density of air and, thus, the timing of the pendulum. 

A clock of Harrison's design was proven a few years ago to keep time within a few seconds over many months.  It is amazing to me that such an accurate time keeping piece was developed in the 16th century.  

John

I did not know that.  I thought it was just to hold the bob.  :laugh