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Continue Sun / Moon rise set, dial output drive assemblies, module frame, horizon shutter cam followers, differential adjustment & dials  - June 2017 

This month Buchanan continues with the output drive section of the sun/ moon rise-set module responsible for the sun revolution, sun horizon shutters and moon sphere revolution and rotation.


Here one sees the ‘technical’ workbench where the design and mathematics are studied and worked out in an “as you go” basis. One can see these drawings and calculations on the desk below the machine components. No detail design drawings for the entirety of each subassembly were made at the beginning of the project. But certain of the more complex subsections were carefully rendered as Buchanan began those systems. Indeed for this module there could not have been complete drawings since the functionality of this complication using Janvier variable differentials was not contemplated at that time.


The first photo shows a jewel being ground down to a smaller diameter to fit in the space between the main master gear and the small gear drive above the bearing. A standard watch jewel would be the right size but too thin since there needs to be a greater cross section to suit the arbor pivot.


Here we see the hole within the brass bearing ring where that jewel will reside. The diameter of the hole is just barely narrower than the width of the ring. Next one can see the contrate wheel that will mount to that bearing. This wheel is part of the drive that gives rotation to the moon.


These photos show the degree of effort made to spoke out even the smallest of wheels. Many other makers would have skipped this laborious step and left it as a solid wheel.

This video shows the initial demo of the revolving platform containing the rotating moon assembly. The complex gearing shown behind this in the second clip are the pair of variable differentials that account for the first and second order orbital anomalies of the moon's orbit.

This drawing reveals the design of the moon drive and is an example of a carefully rendered complex subsystem. The angled drive is needed to correctly position the moon within the dial. An arbor equipped with a universal joint was first considered, but it was discovered that the output needed to be reversed or the moon would spin in the wrong direction. This arrangement allows for a set of idler wheels to accomplish this.

The entire assembly rotates around the central axis at a variable speed controlled by the pair of variable differentials that account for the main part of the moon’s orbital anomalies allowing the moon to rise and set within a fixed horizon. In contrast the sun’s position rotates at a constant rate with a set of movable horizon shutters to account for the seasonal length of the day and night.


Here begins the fabrication of the bracket that will hold the two drive wheels that are angled to each other for the moon drive.


The first photo shows the setting clutch of the moon mechanism; next some of the other parts within the assembly.



The first photo shows an initial setting of the potence jewels for the pair of angled moon drive gears. The following three photos show sections of the bracket being cut and machined away to make it as small and delicate as possible.


A bevel wheel is cut off from the tapered, toothed blank. Next the bracket is now placed within the context of the rotating platform.


Further refinements to the complex bracket shape are performed on the EDM, (electrical discharge machine). The negative mold shown in the first photo is represented by the large copper anode just above the surface of the part. Next the anode is raised to reveal the bracket surface.


The bracket is test-mounted to the platform and next further turning and refinements are made.


The finished bracket now mounted to the platform and the first moon drive arbor is mounted between the bracket and its opposite support potence. Next the arbor is finished off and has the drive and contrate wheels attached to either end and the contrate wheel is now mounted upon the potence jewel.

The drive train for the moon’s rotation is complete. The photo accentuates the diminutive size of this component. Notice the thicker two spokes on the right, these add structural rigidity where needed for the support of the bracket and attached moon.


The rotating platform is now mounted to the sun/moon module front plate. Notice in the first photo how Buchanan has added some decorative turning to the bracket.

Front view of the platform behind the inner twenty four hour dial ring. The square brass blank representing what will later be the module main support frame in seen in the background.

The completed drive platform is now ready to join the rest of the sun/moon module. The solid disks are what will later become the sector gears to drive the sun rise and set shutters. Can you put this back together?


These photos show the rear and front of the retainer cap which will be part of the ‘quick release’ system to allow for the complete removal of the sun/moon module from the rest of the movement; the same as the tellurian, perpetual calendar and will be for the planisphere and orrery.


Now begins the decorative process for the frame plates and other components. Here Buchanan’s mother contributes her design talents. The full plates are shown on the table (the round and square plates), Buchanan says “This is the most rewarding part, a little like when a statue is unveiled”. I am indeed fortunate that he feels this way. Many fabricators view this as the most tedious part as in “the devil is in the details” and try to minimize this most important step to creating a truly spectacular piece of mechanical art.


The first drawing shows the round disk seen in the photo above. This is a sub frame located behind the moon rotation gearing in the center of the dial. It will largely be hidden. Due to other component locations the three legs could not be perfectly made equidistant. The next drawing shows the proposed skeleton design for the shutter sector gears. We retain the nautilus design employed in the snails within the strike work.




The five scans above show the various orientation options for the sector gears controlling the sun horizon shutters. The last example was chosen. The last illustration is a drawing of the rear sub frame for the year drive which powers the sun complication; the horizon shutters as well as the rotating sun indicator.


The main rear frame design, left, shows many similar characteristics to that used for the perpetual calendar, right illustration, which was drawn exactly two years ago. This is another demonstration of Buchanan’s design consistency throughout the project. This makes the entire machine a harmonious whole despite its complexity and diverse subassemblies. There are fewer jeweled pivots in this drawing because of the unique frame design. This is the first assembly that largely does away with a conventional plate and spacer frame where the majority of wheels are suspended between plates. Here there will be one single plate that will have the rotating platform output system suspended from the front and the slant wheel variable differentials from the rear. The jewelling is spread throughout those systems rather than between two conventional plates.


The drawing of the rear sub frame for the year drive is placed over a brass blank. Next a second sub frame is cut.


After all of the holes are drilled into the plate, the hand drawn design is attached to the brass blank, and then the design is scribed into the surface with the razor knife.


Next the blank is cut into a disk and the hand fretting process begins on the jeweler’s saw.


The process continues as more metal is cut away to reveal the curvilinear ivy design.

This photo shows the completed main module frame as well as the year drive sub frame.


The first photo shows a set of eight filing buttons used to guide the hand file while shaping curved surfaces. These were all custom-made for this part of the project. Buchanan could have used a standard set, but customizing a variety gives each component a unique, handmade look. Compare how open the look of this dial has become compared to the same view before the main plate was skeletonized.


The sub frame now has a geared center hub. Next the frame hub is inserted into the central hole of the moon drive.


A second outer drive ring for the sun is added over the sub frame.


The first photo shows a completed horizon shutter sector gear using the nautilus design. Next that sector gear is mounted to the drive. There will be a pair of these for the sun horizon shutters.


A side view of the completed sun, moon and horizon drives. Notice the two shutter sector control gears at the bottom of the assembly in the first photo. Next is the front view.


This video shows the drive assembly. The actual dial hands and other numerical readouts have yet to be added. The sun hand will be attached to the center arbor.

The main module frame now supports the sun, moon; horizon shutter drive mounted to the front and from the rear the Janvier variable differentials controlling the moon's orbital speed. Everything is attached to this single frame; there is no conventional pair of frames separated by spacers where the wheel work is suspended. This the only module within the machine designed this way. 

Buchanan now turns to the development of the year drive for the sun mechanism.


The input to the wheel train is one revolution per day with the output one per year.


The year drive sub frame with all wheels completed is now mounted to the main module frame. Next is a side view.


The first photo shows the quick release catch arm being fabricated. Shown is the clamp ring being split with the slitting saw. Next the flat stock arm is cut out to a decorative ivy design, red arrow.

The sun horizon shutter cam followers are now installed. The jeweled cam rollers 1 and 2 are attached to the sector gears 1’ and 2’. The shutter sector gear 3 is attached to one of a pair of horizon shutters and meshes with cam follower sector gear 1’. The second shutter sector gear is hidden behind it and meshes with 2’.


The jeweled horizon shutter cam follower wheels are seen within the circle in the first photo. Notice how these are near the perimeter of the outer dial bezel. When the cams are fitted they will extend beyond the dial bezel. This same extension of the wheel work beyond the dial was replicated with the time train dual remontoire, the equation differential work and the perpetual calendar overdrive safety clutch. This technique adds to visual impact by emphasizing complexity through the spilling of wheel works beyond the dial perimeter. Next one can see the tight space between the sweep of the moon and the tellurian counterweight. The weight had to be contoured to accommodate a change in the position of the moon sphere.


In the first photo one sees the moon positioned too closely to the inner bezel. The redesign of the counterweight allowed the arbor upon which the moon is attached to be lengthened; positioning it correctly at an equidistant position between the inner and outer bezels.

Buchanan now begins the fabrication of the manual setting controls for the pair of variable differentials.


The first two photos show the machine setup for scribing the inner wheel hub. The scribe is spring-loaded and the wheel is turned to create the circle. The thickness of the rim is determined by the load that wheel is expected to carry and to a lesser extent the diameter of the wheel. A very tiny wheel will need a thicker rim because of machining extingencies. The thickness of the rim is determined by taking the distance from the tip of the wheel tooth to the root and using a multiple for the rim thickness. The rim thickness is the distance from the tip of the wheel tooth to the base of the rim. For lightly loaded wheels the multiple can be as low as 1.1:1. This wheel is lightly loaded but very small so it is closer to 1.2:1. Most wheels are about 1.2:1 and heavy loaded wheels can be up to 2:1. The maximum used in this project are found in the main weight drive wheels at 2.5:1, made in September 2007.



The next four show the spoking out of that very small wheel.


In the first photo drilling the pivot bearing in the large boss, 1, was a little tricky as it is behind the outboard bearing, 2, and a long drill would wander off center. In the next photo Buchanan made a guide bush that fitted into the wheel and a special drill bit. The red arrow shows spade bit. He held the drill in the lathe and kept the wheel in the correct depth and then drilled the pivot hole into the boss.


The long drill is now replaced and the bevel wheel fitted with a proper decoratively machined stainless steel arbor. Notice the use of what I call a compound gear. The inner tooth ring is a proper bevel design and its surface is machined at a 900 angle to the normal teeth around the circumference of the wheel. This allows power to change direction and drive a subsequent set of wheels using only one wheel. We first encountered this in October of 2013 in the two speed transmission for the orrery demonstration drive. There two wheels were mated. Then in October of 2014 when making the drives to the equation and sidereal time a single wheel was used but there the bevel was located halfway between the center of the wheel and its outer edge.


The variable differentials are now equipped with their manual setting control topped with a knurl knob. 


These photos show the differential pair installed within the sun, moon rise-set module. The pair of setting knobs is visible, red arrows.


The first photo highlights a pair of jeweled cocks where one is twisted by the same degree as the slant wheel differential. The two together offer an interesting mechanical conversation. Next one can see the numerous knurl knobs (nine red arrows in this photo) representing a subset of the many manual adjustments that the operator can access within the machine.


The first photo shows an initial mockup for the readout dial associated with the manual adjustments for the variable differentials. Each differential will have a dial delineated with the period governing that anomaly. The next photo shows the artwork design for what will eventually be a pair of enamel sector dials depicting the name of each anomaly and attached to the counterweight of each differential set.


In the first photo the tool which will be used for the differential setting dial engraving is being sharpened and centered so as to eliminate any eccentricities; keeping the tool from ‘wandering’. This becomes a serious issue when the scale and detail gets smaller. The second photo is the engraving machine setup.


The two completed moon differential setting dials, they are about 1.5" diameter (4 cm).

The dials in position upon the differentials.

This photo shows how the left and right sectors of the clock have come into a nice balance. The right side for some time looked to be a bit sparse with only the bell set, but with the addition of the variable differential set the right side has filled out well. The sun-moon, rise/ set dial on the right has a decorative outer bezel to balance with that on the perpetual calendar to the left. That bezel is purely decorative and is the only bezel in the clock that serves that purpose.


This rear elevation clearly shows the gap nestled in the middle between the two upper dials. Here is where the machine will be crowned with the orrery.


This and the next photo further show the balance between the two sides of the clock. In this view one can see on the left side a density of machine work just below the horizontal, silver main upper frame pillar behind the perpetual calendar dial. Just above that it is empty. The variable differential work fills out that same empty space on the other side balancing out the less dense appearing bell set just below where the left side shows density.

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