Complete strike train, begin finishing of celestial train
Buchanan finishes the strike train and begins the celestial train, the last
and most complex train responsible for driving the myriad complications.
Many photos are in large format to give the viewer a good look at the
quality of the parts and finish.
The first photo shows parts making up the strike repeat trip mechanism prior
The parts from the first photo now dismantled and finished.
This photo shows the connection between the parts illustrated in the two
photos above it.
The first photo is the trip lever. Next the finished components of the
Most of the hammer
actuator parts. The two bird analogs on the right will have jewels for their
beaks and this part is what will engage a rotating carrousel driven by
the strike train work.
First photo is one of a pair of the completed quarter strike bird
actuators, second photo.
strike hammer actuator assembly.
The stainless steel arbor and
actuators attain a high corrosion-proof polish.
Finished parts for the quarter strike hammers.
The first photo shows various parts held aloft for lacquering. Next the
completed pair of quarter strike hammer heads and arms.
The completed quarter and hour strike hammer assembly.
The quarter and hour strike train components.
The first photo shows the Buchanan signature that appears next to each of
the three hammer percussion adjusters. The next photo shows a close up of the
re-installed strike trip mechanism.
Another view of the upper portion of the strike trains.
Left, three-quarter elevation of the completed quarter and hour strike
trains, less fly control governors mounted to lower base frame.
Right, three-quarter elevation of the quarter and hour strike trains, strike
less fly control governors mounted to lower base frame.
These are not the strike fly governors,
but one of a pair of the compound fly governors that mediate the functioning
of the time train remontoire. This one is installed on the top of the strike
train, the other is on the top of the time train. It is an example of some
of the components of the time and strike trains being spread out over the
entire mechanism to give visual symmetry and interest. In conventional
construction each train would contain all of the functions of that train.
first photo captures the classical column bases and fanciful finials of the
fly cage. The second photo shows the detail of the upper columns.
--- Buchanan now
begins the celestial train ---
Buchanan begins the finishing process on one of the celestial train's main
frames. In keeping with our naturalistic ivy, tree and animal theme this
"tree" is not simply a flat piece of brass cut into the outline of a tree,
but each branch grows thinner towards the top just as would be expected in a
live tree. The three circles show how the limbs were made in three
thicknesses as one moves toward the top.
The celestial train is by far the most complex of the four trains. The first
indication of this is illustrated by the main frames shown above. At the end
of each branch is a red cover over the ceramic ball bearing pivot point
yielding the bright red fruit of the tree. There are
three train modules but the quarter and hour strike trains are combined into
one module and yet is the least complex compared to the time and celestial
Part of what makes this train complex is the overrun safety clutch described
below. This is the result of the fact that the time and celestial trains
share the power of their two springs. Originally the clock was designed to
be weight driven. The time train contains a lot of what I call "mobiles",
parts that have a lot of movement and so consume a lot of power, in
particular two remontoire and their fly governors. The celestial train
drives many more wheels in the form of the celestial complications,
tellurian, orrery, sun/moon rise-set, planisphere but all of these move very
slowly in comparison to those in the time train and so require far less
power. Having an individual weight for each of these two trains would result
in a huge weight for the time train, over 150 lbs (68 kg) and a relatively
light weight for the celestial train of less than a fifth that of the time train. So the decision
was made to share the weight between the trains allowing for a more even
distribution between the two trains.
However, should there be a malfunction, a jam somewhere, in the celestial
train; given the two trains were sharing the weight load, it would also take
down the time train, stopping the clock. The remontoire overrun safety
clutch was developed to solve this problem by allowing the celestial train
to be bypassed. Relatively late in the project the decision was made to
convert the clock from weight to spring drive and the reasoning is explained
in the July 2019 installment,
but the two trains still share their duties so the mechanism is still
necessary. It is complex, yet beautiful.
These are other parts
of the Robin remontoire. There many ways that the indexing wheel could have
been made and this exemplifies how every part is considered to create a
visual impression. What cannot be seen are slots behind the wheel which are
spaced unevenly. This translates into the remontoire being released at six
different intervals; some a bit less than once per minute some more but on
average the remontoire will cycle once per minute. This translates into the
remontoire fly governor being activated at uneven intervals adding to the
interest to the viewer. The brain is wired to recognize and eventually
ignore a repeating pattern. In this way we keep the interest by making the
fly release at irregular interval. It is also located within the mechanism
so when activated it looks like a butterfly deep within the forest filled
The next part in the second photo is a pawl that prevents
the index wheel from a backward motion.
The index wheel and pawl installed, next a view of a large of a pinion. Note the
detail, Buchanan dishes the larger pinions which
reflects light in a more interesting way than a simple flat surface, also
look at the decoratively turned brass collet surrounding the arbor. The
collect could have been dispensed with leaving the more conventional design
of an arbor and pinion.
Additional parts of the remontoire before finishing.
Additional parts of the Robin remontoire.
The first photo is what is called a "hayfork" lever for its resemblance to
that farm tool. The second photo shows an ivy curly-cue holding a leather friction pad,
which contacts a smooth rim wheel
attached to the safety overrun clutch mechanism, see below.
This is a part of the
safety overrun clutch for the Robin remontoire, it looks like a chronometer
balance wheel. Every screw, every spring down to this minute level is highly
finished and blued, it is just about 1”, (2.5cm) in diameter.
Another component of
the overrun clutch.
The first photo is the remontoire detent attached to one of a pair of
pulleys located at the top of the Robin remontoire. The second pulley is in
the next photo, it's complex articulated rim matches a chain made with
ivy-shaped links. The wheel next to it is the same as the one directly
The completed remontoire overrun safety clutch. The smooth rim wheel is what
the leather pad illustrated a few photos prior to this one operates upon.
each turned column is less than 1/2" (0.75cm). Even at this small scale
nothing is left to anything but perfection.
The complex pulley rim pattern could have been made with solid rim retaining
the pattern, instead it too is skeletonized between the pulley rims; another
detail setting this firm's work apart from all others. This work harkens
back to the index wheel found in the calendar's third-order perpetual module
that was made in February 2015. It too could
have been made in a much simpler way and still perform its function, but
like the pulley illustrated above, was turned from a mechanical object to a
work of kinetic art.
The overrun safety clutch trigger connected
to the long lever that activates the overrun clutch.
In the second photo the trigger is mounted to the inside of a main frame.
This is the trigger-pad which is
the lower limit rest for the over
run clutch. What happens is this. If the celestial drive jams, the larger
weight is lifted until it reaches the "hay fork" lever with the two
blue pad springs and the overrun clutch is activated. The clock will run on
unaffected by the jam. If the problem is removed the remontoire will
trip and drive the celestial train but not rewind until the weight reaches
the trigger pad and then the overrun clutch is reset and the
remontoire operates as normal again. Normal operation of the Robin
remontoire is controlled by the long feed rod from the rear time train frame
and feeds the skeletonized curved tooth indexing wheel with the
inconsistently spaced release slots.
Parts count to date: 4164