Pendulum Clock Construction

[rickman]

I've been looking at clock design for a few weeks and have come to
appreciate the great skill and knowledge that is needed to design and
build accurate time pieces. I am thinking about working on a clock
design of my own. Currently all my background is in electronics, but I
would much prefer to work on a purely mechanical clock.

I found the Shortt-Synchronome free pendulum clock which was the
hallmark of timekeeping for a number of decades in the 20th century.
It's design is a bit complex and uses a primary free pendulum in an
evacuated cylinder. Then I found information on a clock by Fedchenko
with an "isochronous" pendulum using a triple spring suspension. The
restoring force of gravity on the pendulum is not purely linear with the
angle. This creates a dependence of the period on the amplitude of
swing. The Fedchenko design uses two short springs and a long spring.
With their alignments offset vertically the middle, long spring gets an
extra bend from the rotation about the lower pivot point controlled by
the two short springs. This is enough to minimize the non-linearity of
the gravity pendulum.

While much of the clock construction would be a learning experience for
me and present many obstacles, I think constructing such a suspension
spring would be out of my abilities.

Anyone here build their own clocks?

[Jeff Wisnia]

Post by rickman
I've been looking at clock design for a few weeks and have come to
appreciate the great skill and knowledge that is needed to design and
build accurate time pieces. I am thinking about working on a clock
design of my own. Currently all my background is in electronics, but I
would much prefer to work on a purely mechanical clock.
I found the Shortt-Synchronome free pendulum clock which was the
hallmark of timekeeping for a number of decades in the 20th century.
It's design is a bit complex and uses a primary free pendulum in an
evacuated cylinder. Then I found information on a clock by Fedchenko
with an "isochronous" pendulum using a triple spring suspension. The
restoring force of gravity on the pendulum is not purely linear with the
angle. This creates a dependence of the period on the amplitude of
swing. The Fedchenko design uses two short springs and a long spring.
With their alignments offset vertically the middle, long spring gets an
extra bend from the rotation about the lower pivot point controlled by
the two short springs. This is enough to minimize the non-linearity of
the gravity pendulum.
While much of the clock construction would be a learning experience for
me and present many obstacles, I think constructing such a suspension
spring would be out of my abilities.
Anyone here build their own clocks?

The only clock I ever built from scratch is the antithesis of what
you're looking for rickman.

It's a verge escapement wooden clock. I built it over 25 years ago and
its still hanging on a wall and runs as it did though I seldom "wind" it
these days.

It was fun turning the circular parts on my Stark metal lathe which
according to the markings stamped on it spent its life in the Waltham
Watch Works prior to my buying it from some guy via a predecessor to
Craig's List.

I borrowed an indexing head from a friend who owned a machine shop and
used it to help cut properly spaced teeth on the three gears and two
pinions in the clock.

Enough already, here it is:

http://wkrp.org/jeff/clock.html

Jeff

[rickman]

Post by Jeff Wisnia

Post by rickman
I've been looking at clock design for a few weeks and have come to
appreciate the great skill and knowledge that is needed to design and
build accurate time pieces. I am thinking about working on a clock
design of my own. Currently all my background is in electronics, but I
would much prefer to work on a purely mechanical clock.
I found the Shortt-Synchronome free pendulum clock which was the
hallmark of timekeeping for a number of decades in the 20th century.
It's design is a bit complex and uses a primary free pendulum in an
evacuated cylinder. Then I found information on a clock by Fedchenko
with an "isochronous" pendulum using a triple spring suspension. The
restoring force of gravity on the pendulum is not purely linear with the
angle. This creates a dependence of the period on the amplitude of
swing. The Fedchenko design uses two short springs and a long spring.
With their alignments offset vertically the middle, long spring gets an
extra bend from the rotation about the lower pivot point controlled by
the two short springs. This is enough to minimize the non-linearity of
the gravity pendulum.
While much of the clock construction would be a learning experience for
me and present many obstacles, I think constructing such a suspension
spring would be out of my abilities.
Anyone here build their own clocks?

The only clock I ever built from scratch is the antithesis of what
you're looking for rickman.
It's a verge escapement wooden clock. I built it over 25 years ago and
its still hanging on a wall and runs as it did though I seldom "wind" it
these days.
It was fun turning the circular parts on my Stark metal lathe which
according to the markings stamped on it spent its life in the Waltham
Watch Works prior to my buying it from some guy via a predecessor to
Craig's List.
I borrowed an indexing head from a friend who owned a machine shop and
used it to help cut properly spaced teeth on the three gears and two
pinions in the clock.
http://wkrp.org/jeff/clock.html

Nice clock. I like it. I thought about making something relatively
crude like that as the display for an electronic clock synchronized to
the WWVB time signal so it would always be accurate. I especially like
the single hour hand. Now that I'm retired I either need to know the
time to the second (for some computer stuff) or just to the nearest half
hour is fine.