Continue digital year indicator and calendar readout control levers
- May 2015
mask of the decimal year counter. The faceted wheels compliment this
arrangement nicely. One can see that such a mask is necessary to cover the
spaces between the decimal wheels. Given the need to have the drive pinions
between the wheels there is no way around the space needed between the
wheels and so a mask is necessary to give the counter a clean look.
who likes to see the details of a particular mechanism might ask why we are
hiding the decimal and carry pin assemblies. The simple answer is that we
are only masking these features from the front angle view. If one looks
above or below these features are completely visible. The mask is no
different from the enamel rings we employ for the dials. One needs some type
of background to make sense of the various data readouts from the machine.
We see here an overall front elevation of the movement with the calendar
continuing to take shape.
Buchanan now begins to
flesh out his concepts to drive the counter and the evolution is illustrated
The individual drawings are shown below. These serve as both an illustration
of how Buchanan develops his ideas for the design of a component as well as
the the way it would have been done by the master clockmakers centuries ago
before the aid of computer design.
As is the case in much
of the rest of this project, accomplishing the power feed was not straight
forward. One cannot simply have a drive coming from a constant source, say
the time train since this is part of the calendar which is driven from the
celestial train. Either way, the year has to change over in accordance with
the perpetual calendar in which it resides. So it must follow the lead of
the perpetual module. The problem here is that we have the drive train
actuated daily within the calendar works. But only the day and date dials
are driven daily and the date is also controlled through the perpetual
module. Therefore we need a series of levers and detents that act as ‘logic
gates’ to allow the other dials to change at the appropriate time even
though the drive gears behind them move daily. This is one of the reasons
why the Burgess clutch was chosen over conventional friction clutch work. In
the latter, the clutch would be acted upon daily leading to premature wear.
In the Burgess design the friction is next to none. Why not simply connect
the year counter directly to the calendar drive train? Here we have two issues. The first is the
fact that the drive train is initiated daily without regard to the variances
of the leap years. So while the rest of the calendar would be correct since
it is controlled by the perpetual module, the year counter would, after a
few years, be seriously out of step with the New Year. The next reason is
that we need the year to ‘flip over’ instantaneously at twelve midnight on
December 31st. A direct drive would cause the year digit to
slowly move throughout the year. While other makers might have compromised
on this last issue, we will not.
First Buchanan has to
outline the functionalities required.
the first drive
concepts are fleshed out. The four vertical rectangles represent the year
counter digit disks.
The first sketch is an overview of
the clutch design.
detail of the clutch release is
sketched. The pivoted lever design was later modified to a cam.
Now tooth and pinion
counts are assigned to turn the concept into a practical design that can be
made into the actual components. Yet even at this point, we really do not
see any actual recognizable components. These are all made ‘as we go’. This
is another testament to Buchanan’s incredible abilities as they apply
to design and fabrication.
Next a few of the parts are realized
upon the stylized drawing.
Here we have the drive
train to the year counter being fabricated. The last photo shows the
combination drive/bevel wheel set.
The first photo shows a
staking tool to insert the arbor that will connect both the bevel and
standard drive wheel. Next a jig is set upon the movement plate to position
the thread tapping tool perfectly parallel to the plate in which it will
create a threaded hole.
Here holes for the
jewels are drilled in the cock that will hold the drive/bevel wheel. These
are drilled simultaneously from above to give exact perpendicularity.The next two photos show this gear set connected to the leap year
The drive to the year
counter is fabricated. It is a bevel wheel that is driven from the drive
bevel wheel shown above.
These two videos demonstrate the bevel drive to the digital year counter.
Here we have a view of
another interesting and unique wheel. This eight sided cam serves the same
purpose as what a ‘star wheel’ does in conventional clockwork. It will
‘click-over’ the digital counter in a discrete movement once per year at
midnight rather than in a continuous motion throughout the year as what
would be encountered a conventional odometer. For people who are very
observant and have closely followed this project over the years you will
notice that the jeweled roller wheel looks familiar. It is, in fact, a
repurposed part that was originally designed for our grasshopper escapement
back in January of 2009. That design was later
changed and this part became unnecessary. There were four of these, so maybe
Buchanan will find another location in the future for the other three?
These photos show the
major components of a clutch that will control when the year counter is
engaged. As with many other systems in this machine, the way the counter is
engaged is a bit more involved than one might expect in a conventional
application. The drive wheels behind each dial are all meshing together and
when being driven under normal conditions, that is when the clock is not in
demonstration mode, are briefly driven once daily at midnight through the
remontoire. A full explanation of this will be made later as the calendar is
developed, but at this point suffice it to say that one cannot simply have a
direct drive to the year counter from the calendar wheel drive train. If it
was it would be activated daily instead of yearly, hence the need for the
clutch which will allow the counter to be driven by the calendar drive once
The first photo shows a
jeweled roller that will act upon a cam seen in the next photo. When the
clutch is activated at midnight on December 31st, the horizontal
arbor will rotate the attached cam by one revolution, (arrow 1). The cam allows the dog tooth
clutch to engage for just the right amount of revolution to advance the year
by one digit, (arrow 2).
In this video the cam control for the dog clutch is
demonstrated. In practice the clutch would drive the digital counter once
per year at midnight. The digit turn over will be perfectly aligned with its
neighbor once the eight-sided cam on the right is completed.
The completed digital year counter. It looks a bit like
the year counter in the time travel vehicle from the 1960 movie based on
Jules Verne's book, The Time Machine.
This is a roller which
controls the time when the dog clutch is allowed to engage. In the second and
third photos one can see the roller partially pushing against the flange of
the left hand side of the dog clutch resulting in those teeth being pried
halfway apart. This is just for demonstration purposes. In reality the
roller will hold the clutch open and thus disconnect the counter for all but
one day of the year. Then on December 31st it will snap leftward
via a momentary connection to a lever which will be controlled by the logic
machinery of the rest of the calendar work; allowing the clutch to turn the
output wheel to the counter to advance the year digit by one. The logic
machinery accounts in perpetuity when the year should change.
The part cut out forms the center section of the slave connector
between the leap year detent and the year counter so when the counter is
tripped the leap year detent is also lifted.
The matchstick gives an
indication of how small this part is. The arrow points out the roller,
described earlier, which holds the clutch open preventing the counter from
advancing except once yearly. The center bridge in the second photo is the
slave connection to the leap year detent.
These photos show the
fabrication of what will eventually be six dual armed cams that will form
the basis of a controller actuating the various levers connected to the
detents on the crenulated dial wheels and others that will read pin
positions. These cams will be mounted to the arbor of the drive input wheel
which is fed directly from the calendar remontoire. In the parlance of
computer design the drive input acts as the ‘clock controller’. In other
words all of the functions of the rest of the calendar are performed during
each cycle of the input drive. In this case one-half revolution per day.
The combination of the various rotating
cams, rockers, levers; bias springs, detents and
crenulated wheels compose the ‘logic circuits’ of this mechanical analog
computer complete with cycle clock controller, a fixed program and memory
(in the form of the perpetual modul).
These are represented diagrammatically i
n the realm of
computer programming by logic gates which in turn are connected to form the
circuits. The basic logic gates were described in the
April 2015 segment.
The first photo shows
the initial milling of each part. These parts are one of the first times
that Buchanan has employed a computer aided milling machine. The fact that
we will need six identical complex parts made this a good choice. Now the
question is, how does one remove these parts from the surrounding material?
Here Buchanan employs a clever technique. He fills the milled out sections
with car body repair filler, known here in the United States by the generic
name, Bondo and this can be seen in the second photo.
Next the parts are milled from the opposite side until enough material is
shaved away to meet where the Bondo is filling the spaces from the part from
the front, third photo and first one below.
Next heat is used to
soften the Bondo and the parts fall cleanly away.
A rocker part being prepared for milling. There were three of these
identical parts needed.
Of course a part made by
a CNC mill still needs many additional machining and finishing steps before
completion. Here we have the cam’s collect being decoratively shaped. Next
the rest of the cam profile is filed by hand. This cleans up the machine
marks but also gives the part a hand-made finish by introducing the subtle
imperfections in the part’s shape that would be absent from a computer
generated part. I can’t speak for others, but I know that I can spot a clock
made entirely from a CAD-CAM design and production. Only a handful of parts
in this project will be made in this fashion since there are few areas where
a number of identical parts are needed.
This part is an example
of one of the lever rocker arms and pair of one-way impulse paddles. The
impulse paddles are shown by the black arrows. Each is a compound paddle
made of two parts. The paddle itself, arrow 1, is mounted loosely on the
arbor and can move back and forth leaving the arbor to which it is mounted
unaffected. The paddle is actuated by one of the rotating input cams mounted
in what was described previously as the ‘clock controller’ in the mechanical
logic circuitry of the calendar. The area of contact is near the tip of
arrow 1. The input cam can rotate in either forward or reverse. If the
paddle is pushed in one direction, upwards in this photo, the paddle will
push the pin connected to the curved part next to it. That piece is fixed to
the arbor and will cause the entire arbor will rotate in a small arc. If the
cam encounters the paddle in the opposite direction, the paddle swings away
from the curved piece and nothing happens. The occurs for the second paddle
but in the opposite direction, arrow 2. The part below that is a
lever rocker and is fixed to the arbor. This basically converts the rotary
motion of the input cams into a back and forth motions. The two pins located
by arrows 3 and 4 will push against the various levers that will ultimately
control the outputs of each dial in the calendar. The spring acts as a
return bias for the rocker as soon as the rotating cam has passed the point
of contact on the paddle. The calendar will require three of these units,
but the configurations and locations of the paddles on each one is
In this video
we see a single pair of rotating
cams out of what will be three pairs as well as one of three lever rockers.
Each lever rocker is actuated in either forward or reverse of the rotating
cam depending upon whether it is contacting an active or passive paddle. The
rotating cams provide the impulse timing for all of the interactions of the
rest of the components forming the logic circuits in the calendar. The
calendar moves ahead or in reverse depending upon the rotation of clock's
drive and the cams which are mounted to it.
The month wheel in the
first photo shows a straight bar with a pin on the upper arm. This is the
year select pin mounted to the month dial drive and which will come into
play once per year in December. When another lever senses a pin on the
perpetual date mechanism immediately above indicating that it is the first
day of the month, then together these will signal the slave connector lever
to allow for the year counter to advance.
The calendar is now taken to pieces for the next phase of construction.The second photo shows two of the three rocker assemblies
having compound impulse paddles.
One can see the differences in the parts configuration between them.
Above is a photo of many, but not yet all, of the connecting levers
that bridge the mechanical circuit from the timing cams mounted on the input
clock drive to the detents that control the output to the calendar dials.
This photo brings to mind what Buchanan had said when beginning
the complex set of connecting linkages for the strike train back in December
2010. He said making wheels is easier and
rather straight forward in their fabrication, positioning and depthing. But
levers have a far more complex set of criterion than a simple wheel center.
They move in two dimensions while wheels remain fixed in one position. Any
small change in their shape or displacement in relation to the object they
act upon or are being acted upon whether that be a cam or another lever
becomes a complex problem to solve. Long levers that have compound movements
in relation to each other will, by the very nature of their geometry,
magnify any error in the design of their shape or the positioning on their
This three-quarter view
shows some of the complexity of the calendar components. The logic clock
drive is represented by the drive wheel,
B and arbor
A. The wheel just barely visible
below the circular opening in the brass plate belongs to the remontoire.
Upon arbor A are mounted the six
rotating timing cams which begin the logic circuitry of the calendar
numbered 1 through
6. The first cam is largely
obscured by the upper temporary plastic plate. The two circled areas show
two of the three rocker assemblies, the third being obscured by components
in the foreground.
These two photos show a
side and top view of the clock drive arbor with the timing cams. Notice in
the second photo how the stack of timing cams appears to be closely matched
one on top of the other but they are not precisely aligned in the vertical
plane. There are subtle differences in the timing of the actuating levers to
the various calendar components. If these were indeed perfectly aligned
there would be no need for six individual cams, only three would suffice.
Today Buchanan begins another lever for the calendar as seen in the first
photo. This oversized piece is fitted into the existing assembly to test for
clearances, next photo. The same procedure as has been done countless
times before when a lever is made. This exercise was especially prevalent in
the strike train.
These photos show the development of a triple compound lever for the year
select function. First a paper pattern is made to the largest size that can
be fitted into the available space. This allows maximum flexibility for
to create what he calls “the prettiest form to connect all the vital
The third and fourth photos show the three rough forms,
3, layered one upon the other
and these are pivoted on a pair of pivot points,
5. The entire set is supported by and rotates in a small arc around
arbor, 6, (out of field of view,
Here is a pair of great before and after shots of the year select lever.
What a lovely transformation! I think Buchanan succeeded in finding the
prettiest from to connect all the vital parts.
The numbers are referring to the same parts as before. The names
reflect the lever's function. The month select lever checks for the month of
January. The date select checks for the first day of the month. When both of
these inputs get a positive signal, the output lever will allow the year
counter to advance an example of an AND logic function.
Here the compound lever is installed.
1 is where the date select lever
is positioned, 2, the month
select lever and 3 is the output
or operand lever. In other words if the levers represented by
1AND2 are both correctly
encountering a pin, these will deliver a signal, (a push) to the output
(operate) lever that will connect to the year unlatch lever allowing the
year counter to advance. This is an example of a mechanical AND gate where
if two conditions are met, there will be a positive output.
The year select lever now has its impulse connector installed. The push this
lever will give to the compound set of levers will allow them to detect if
the pins for the first of the month as well as December are in their correct
positions. That impulse is given by the logic cams attached to the input
rotating arbor, the ‘clock’ for the calendar logic circuitry. The next photo
shows the select lever with its impulse lever installed,
The year select lever is now installed.
It reaches diagonally from the upper right hand corner to the lower left
where it connects with the rotating logic cams.
This view shows clearly the
complexity of parts that have been installed so far within the calendar.
In this video
the year select lever is demonstrated under all
conditions of its function. First with the lever touching (reading) both the
day and month pins resulting in a positive push - output (operative) to
actuate the year counter release. Next with only the day pin read, next only
the year pin read, and next with neither pin read; under all of which there is no operative. And finally back to both date and month
pins read. This compound lever assembly is one example of the logic gates
used in the calendar. In this case it is an AND gate where both conditions
of reading the date and month pins must be met for there to have an output.
The second video shows the year select lever controlling the year
counter under a demonstration drive. The year counter is now equipped with
the star wheel and roller giving the year rotation accurate positioning. The
year select lever is now reading from the perpetual calendar module and
controlling the release of the counter. The year for this demo advances at
each half rotation of the cam pack, but in reality this is not the case. The
cam pack normally rotates one half revolution per day the year counter will
advance only when the logic circuitry through the perpetual calendar module
permits it to change.
These two photos show the installation of bias springs on various
This shows a good view of some of the actuating levers. These follow
the same curvilinear, organic ivy and spur design developed throughout this
project and also demonstrated extensively in
Perhaps this side elevation will give the viewer a bit more appreciation for
the calendar subsystem’s complexity. The calendar module with its remontoire
drive and safety clutch components requires a quadruple plate structure
which is easily seen in the first three metal plates and then completed by
the temporary plastic front plate. When the plates are finished there will
be very little left of the two rearmost plates. The entire calendar and its
remontoire are completely removable from the rest of the clock via one
photo gives an additional impart as to the overall complexity that the
machine has taken on so far.