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Finishing the thermometer, demo drive crank, begin strike train components - March 2020

This month Buchanan moves on to the final finishing of the thermometer, demonstration crank drive and begins the strike train components.  

The bluing oven is now reliably turning out blued screws and other parts in large quantity.  


The first photo shows the thermometer assembly before finishing. Next most, but not all of the components. Note the design of the stirrup-shaped part in the bottom row of components. This is a tiny sector gear and the same design is also used in the strike/repeat mechanism which will be seen in April's installment. Buchanan's use of unique component designs that are carried through to other components gives a continuity to the project's design.


Here we have the tiniest parts, note the watch-sized fusee chain and tiny knurled knob. Next are two metal rings, steel and brass that form the bi-metallic component which translates a change in temperature into a physical movement, also known as a bi-metallic strip, this same concept is still used in temperature controllers today.


The frame with some components are finished. Next the center biasing spring, frame columns and the bi-metallic strip installed.


This photo shows how small the components are in relation to the fingers holding this assembly. Note the numerous screws (37) holding the two metal rings together. This method of making a bi-metallic strip was the first used after its discovery for temperature measurement. There is a large amount of force that comes to bear in this construction and many screws are necessary and must be very tight to keep the two rings from slipping past each other instead of forcing the entire ring to expand and contract with the change in temperature. The same concept of different metals having different amounts of expansion and contraction was first used in horology by John Harrison in his gridiron pendulum. However, in that application the differing metals were allowed to slip past each other in order to cancel out the expansion or contraction that a pendulum made of only one metal would have. Here the expansion and contraction are magnified by binding the two metals together to produce movement for a readout of the temperature. This design of holding the differing metals together was soon supplanted by the direct fusing together of the metals which was far cheaper and more secure than using screws. But in keeping with the philosophy of this project, the screws are far superior in visual beauty, and Buchanan has taken steps to be sure they will remain secure. 


The first photo is the pillar upon which the thermometer will be mounted and transfer wheelwork for the tellurian. Notice the beautiful blued screw in the first photo. The next photo shows the thermometer mechanism installed in front of the demonstration transfer wheel.

The thermometer now mounted within the machine; another view of those beautiful screws.



The first three photos show the demonstration drive input wheels. Notice the two square arbors which accept the manual operator crank key. The arbor to the left has an output of twenty four hours per revolution, the one to the right multiplies by ten. The fourth photo is a set of transfer wheels within the demonstration drive wheel path.

The demonstration drive and transfer wheels are installed, the demonstration component is also connected to the tripartite drive located to the left, but not yet installed, for the calendar, equation of time and sidereal time complications.

This photo illustrates the demonstration drive schematic. The two red arrows point to a pair of arbor squares where one would fit a manual crank. Arrow 1, on the left will cover twenty-four fours per revolution. Arrow 2 to the right performs the same demonstration function but geared to a rate of six  revolutions per day.  The yellow lines show the pathways from the manual drives to the individual celestial complications. Note the double vertical line leading to the orrery marked A and B. They meet at a point in the middle of the two smaller dials to either side. This is where a controller allows one to engage and disengage the demonstration function. At this point is also another arbor where one can use a key to move the entire celestial train at twelve turns per day, this is useful in "fine tuning' the display for accuracy, by allowing one to approach midnight for the trip of the calendar while manually setting the rest of the celestial objects as these are all individually adjustable by hand.

Furthermore one can also change the speed at which the orrery will operate. Through drive line A, the orrery will operate at one of the two speeds provided by the operator at arrow points 1 or 2. One can also disconnect the orrery from the rest of the machine and operate it on its own in “fast mode” as represented by line B. The orrery contains the planets Jupiter and Saturn. Jupiter take over 12 years and Saturn 29 years to make one orbit around the Sun. So one will never be able to see the relative speeds of these planets by using the time frames allowed when the demonstration is operating on all of the celestial simultaneously. The time frames for the rest of the celestial functions move visibly with just a few turns of the 24 hour demonstration drive, cycling from daily up to yearly.

--- Buchanan now begins the strike train ---

Buchanan now begins final procedures to the strike train. This train contains both the hour and quarter strike trains and is the last of the drive trains mounted to the base frame to be done. Pictured above are a subset of the strike control components.


The first photo is the hour strike rack first completed in July 2011, next the hour snail cam with the elongated bird neck that serves as the strike repeat actuator. This was first completed in July 2014.

The strike control components completed so far.

Two of the rack gathering bird analogues. The lower one before finishing compared to the finished one above. These are made of stainless steel which is quite hard and therefore takes more work to polish, but once done give a lasting lustrous finish.

Rack gathering parts as well as part of the strike drive. The twisted arbors will power the strike fly fan governors. One of Buchanan's signature styles is the dishing of larger pinions which give a more complex play of light than a simple polished flat surface.


The twisted arbors were something I had thought of very early on in the design process. The longest one is used in the drive to the remontoire fly set located on the right hand side of the machine over the strike train but is driven from the time train on the left where the pair of Wagner remontoire are located and so must span over the center celestial train. The other two drive the dual grasshopper escapement wheels. There is another pair in the photo above this one which are used to drive the strike fly fan governors. Basically we chose arbors that would turn relatively fast and were exposed to give the viewer further entertainment and to show how the power was distributed, since the ‘flow’ of the spiral, like a barber’s pole is directional and that flow follows the path of the driving force. Next photo a close up of one of the gathering pawls showing the interplay of color and attention to detail.

Pictured above are the quarter and hour gathering components. These raise the quarter and hour racks once the strike cycle begins one tooth at a time and each iteration allows for the quarter or hour bells to be struck. This double gathering design was based upon the way counting racks were gathered within the Easter calculator made by Jean-Baptiste Schwilgue in 1843 and still exists today in the Strasbourg cathedral, France, but further refined by Buchanan.


The first photo shows the main frame components of the strike train, next a close up another one of Buchanan's signature styles, the exaggerated spring curve used where space allows, (space, where is there any spare space in this mechanism)! Notice the purple color of the ratchet pawl. There are a few ratchet pawls that have blued differently than the rest of the steel reserved for bluing. The others are located in the main winding barrel assemblies, we are not sure why, but kept them as they add visual interest. Note the decorative tail at the end of the pawl. The steel that we blue is different from the stainless steel used in all of the other silver steel colored components. With the exception of pinions, those are made from stainless steel which due to its alloyed elements will not blue.


These comprise the strike actuating carrousels. In this area we decided to depart from the standard straight spoke design and do something whimsical.


A set of bird analogues will be pushed by each of the pillars located between the carrousel wheels, see below.


The spokes almost look like chiffon swirl on a tasty desert. 


The first photo shows the screen from a computerized wire-cutting machine depicting a replacement bell hammer spring. In the next photo the spring is cut from an old hacksaw blade. The material is ideal for this application as it is exceptionally strong and resilient.


The old spring design, bottom and its replacement, top. The added coils provide a smoother and more consistent power throughout the duty cycle of the spring upon the hammer. Buchanan was unsure how well the hacksaw material would blue and was prepared to leave them as a steel polish, but they blued up beautifully.


Here we see two views of a bell hammer assembly. The new spring design is a big improvement from the original.


The first photo is another bird analogue, its beak engages the pillars on the carrousel cage which is driven by the strike train, pushing the beak and raising the hammer which recoils when the beak slips off the pillar. The second shows a part of the strike mechanism.


Look at the bevel wheel and its drive in these two photos. The cock that holds the drive pinion is mounted to the wheel arbor which it drives and is free to rotate upon that arbor. In a conventional design the cock would have been attached to some external component, a frame or post that is not connected to the wheel being driven. This is the first time I have seen this design application within the realm of horology. The cock is too deep within the machine to have a convenient external mount.



Parts count to date: 3018. 

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