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Continue digital year indicator and calendar readout control levers and  - May 2015 

This is Buchanan's 'first draft' for the design for a 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.


Someone 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 below. 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. Next 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. Next a 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 drive.

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 per year.


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

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We now return to the calendar control assemblies 

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 in 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 different.

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 respective arbors.

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 Buchanan to create what he calls “the prettiest form to connect all the vital parts”.  


The third and fourth photos show the three rough forms, 1, 2, and 3, layered one upon the other and these are pivoted on a pair of pivot points, 4, and 5. The entire set is supported by and rotates in a small arc around arbor, 6, (out of field of view, second photo). 


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 1 AND 2 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, yellow circle.

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 parts.

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 the strike train control systems.

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 fastener.

 This photo gives an additional impart as to the overall complexity that the machine has taken on so far.

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