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Fabricate dial support latches, polish equation and time transfer trains, tripartite drive, escape wheel assembly, rack let-down flies, orrery drive - February 2020

This month Buchanan continues the final phase of the project, the refining and polishing of all components. In this installment the fabrication of bezel support latches are made for the tellurion and mean time dials and an improvement in the strike detents. Finished are the time transfer and equation of time trains, the tripartite drive for the calendar, sidereal and equation trains, the escape wheels and anti-friction wheel support structure, the strike detent and rack set-up a flies, and part of the orrery drive. 

 

In these photos one can see the occasional use of CAD-CAM used on the project. This is used when there are multiple identical parts, which has seldom occured. In this instance Buchanan is cutting the dial latches.

 

Illustrated is an example of some of the remaining fabrication work needed on the machine. Buchanan has made a set of quick release latches for the mean time and tellurion dial bezel support rings. The first photo is the mean time dial from behind and one can see where it attaches to a pair of pillars one of which holds the tripartite drive off to the left, (more on this later in the segment). The second photo has the tellurion transfer wheel, but the dial ring will pull away while the transfer wheel stays attached to the clock frame.

The pillars are now shown after decorative turning and all the parts are polished.

Equation of Time Differential 

Shoen above are the wheels and cam follower arm.

 

The equation cam follower arm is shown above. It has a jewel bearing set into a steel rim. The follower recently had a bias spring installed to ensure it remains seated on the equation cam. Next the frame pillars are decoratively turned.

 

The completed equation of time differential wheel works, less the cam follower (left), as compared when it was first fabricated in July 2010.

The completed equation of time differential.

Equation differential wheel train parts, 121, total to date: 1820.

Tripartite Drive

The tripartite drive is a combination of three drives from one source, for the calendar, sidereal and equation of time complications. This was first begun in September 2014.

 

These two photos show the frame with pillars now turned. The pair of curved parts that look like insect mandibles are jewelled pivots for two drives aimed at complex angles. Although it may look like Buchanan simply took a pair of pliers to twist the metal to this shape, in reality these are much too thick to do this and they were cut by hand with a piecing saw from a solid block of brass. The curve of each potence had to be precisely shaped to ensure the pivot jewels mounted at the end of each curve had their holes aligned perfectly parallel to the two arbor pivots that must fit there. The first photo certainly evokes the analogue of an insect with a pair of antenna tipped with red spots coming from behind the jewel chaton head and a pair of mandibles below; although this insect only has four as opposed to the requisite six legs.

 

A sample of the complex turning of the frame pillars. Next most of the wheel components for the drive.

 

The first photo shows conventional way many clockmakers would approach the need for two different diameter wheels spaced closely and fixed on one arbor, by sandwiching one on top of the other. The next wheel in interesting, Here we have not only two wheels of differing diameter but the inner also being a bevel. Again it could have been done as the other two, but the depth clearance was critical and there was not enough space for a sandwiching of two separate wheels. So here Buchanan makes both wheels from a single brass blank effectively countersinking  the smaller wheel into the larger. Even here Buchanan keeps the spokes thin, in fact if you were to measure the width of the spoke from the hub to rim, it has the same taper as if there were no second bevel wheel in the middle.

 

First photo shows the wheels installed on the front frame and next the frames completed, it also shows the component from the outside with the demonstration dial mount and gives the viewer the comparative size of this component.

Pictured above is the completed tripartite distribution system which feeds three separate complications. The sidereal drive requires two revolutions per year, the calendar drive one revolution in 24 hours and the equation drive one revolution per year. Notice the small decorative turning in the middle of the calendar drive arbor. This is a view as it would be seen from the inside of the machine. From the outside the photo would be flipped about its horizontal axis.

Tripartite distribution drive 80 parts, total to date: 1900.

Time Transfer Train

In conventional clockwork the time, quarter and hour strike trains are close enough together that communication between the trains can be accomplished through levers comprising the strike work linkages. In this clock the time train is located on the left side of the clock base with the strike trains located at the opposite end and the celestial train located between. The time transfer train is needed to bridge the gap occupied by the celestial train; enabling the time train to synchronize to the strike train's snail cams. It is a set of idler wheels designed to look complex and beautiful. One could have used a row of wheels that were all the same size but the style of fabrication used throughout this project is what we call "Buchananization" which calls for an interesting presentation and making wheelwork that fills all the available space to make what is already a complex machine appear even more so. This was first fabricated in October 2010. The machine looked quite different back then.

Compliment of parts for the time transfer train, less some parts: jewels, screws and taper pins.

 

The first photo shows a red, plastic ring made to look like a jewel, behind this is a ceramic ball bearing holding the tellurion transfer wheel. The next photo shows a true jewel pivot for each time transfer wheel.

 

 

To keep the time transfer train looking as light as possible the wheels run on only one frame instead of between a pair as would be expected in a conventional design. The way to achieve this is to run the wheels on arbors attached at one end to the face of the frame and with the taper hole on the other end to secure the wheel; these are referred to as 'dumb arbors', first photo.

Completed time transfer train which runs along the rear side of the clock. The wheels all run on just one frame to make this look as light as possible; like buds or flowers on an ivy vine. This in keeping with our organic design theme throughout the machine exemplified by the main frames to look like trees holding red fruit of ruby colored pivots surrounding a forest of wheels interspersed by curvy ivy shaped parts. Bird analogues inhabit the forest, and in the firmament above is the Sun Moon and planets of the orrery.

Parts count for the time transfer train, 69, tellurian transfer train, 17, total to date: 2003.

Escapement Wheel Pair and Support Assembly

The escapement assembly as many other components in the clock is very different from conventional clockwork. The escapement is not located in the time train but in the celestial train. The reason for this is, again, for visual presentation. To have the escapement be directly in the middle of the clock, it must be located where the celestial train is located. As the strike trains must be coordinated with the time train remotely, the escapement is driven by the time train through a long pair of arbors that reach across the space between the time train and where the escapement assembly is located. The escapement wheel assembly consists of a pair of counter rotating escapement wheels and the compliment of antifriction wheels that support it; also on the same frame because of its location, is a small wheel set that connects to the orrery drive. Fabrication began in August 2008.

These parts comprise the anti-friction wheel support assembly for the escape wheel pair.

 

The eight ant-friction wheels are shown in the first photo with their support frames emphasizing the jewel chatons.

 

This is a connecting wheel to the orrery drive that is mounted to the escapement wheel frame due to the proximity needed for this part. Notice the differing colors of the brass upper wheel to the pink bronze bevel below. The next photo shows this part on the escapement wheel frame along with an adjacent set of anti-friction wheels to support the escape wheels pair.

 

 

Four photos showing the grasshopper escapement wheels.

 

 

This photo shows the pair of counter rotating grasshopper escapement wheels as well as their two bevel drive wheels, first fabricated in September of 2008. The execution of the swirled spoke design for the escape wheels must be one of the more difficult spoke designs to execute in this project. Look at the inner hoops within the two drive wheels. These are guide rims that along with another pair of same-sized hoops will keep the escape wheels in position upon the antifriction wheel rims.

 

These two photos are the pair of guide wheels that fit closely between mating hoop rims as illustrated below.

This photo shows how the escape wheels are held in position upon the antifriction wheels. There are no pivot holes or arbor shoulders adjacent to those pivots to ensure the correct positioning of the escape wheel rim in relation to the escapement pallets as would be found in conventional clockwork. The horizontal guide wheel pair, (two photos above), fit closely between the inner rims of the toothed drive bevel wheels and the smooth rimmed wheels opposite. It’s important to note that there is a very small amount of clearance between the distance of the two vertical rims and the horizontal guide wheel. Just enough to ensure proper alignment of the escape wheels with the clock’s pallets, but not touching both at once which would cause a lock-up of the escapement. What makes this design interesting is that those guide wheels will also turn along with the escape wheels making for another interesting piece of machinery to look at.

 

Front three-quarter elevation view of the escapement assembly.

Entire escape wheel and support assembly with additional orrery drive wheel in the back.

Escapement wheel and support assembly 262 parts, total to date: 2293.

Strike rack let down flies and strike cycle detents

These birds are the detents that engage the strike fly fan to initiate and stop the striking sequence. 

This photo shows another ‘housekeeping’ item Buchanan has attended to. These are the pillar mounts for the strike train detents that take the form of a bird, (photo above). The fly fans moderate the drop of the quarter and hour strike racks as they are large and heavy, and give the viewer another pretty thing to look at as the strike sets up. The pillar on the right is the original design, on the left Buchanan has added a bias spring and armature that will engage the bird detent. This ensures positive locking. Note the "Buchanan logo stamped on the base.

One pillar with the new bias spring configuration mounted to its cross bar base.

 

In the first photo a view from the back side showing a jeweled chaton for the bird detent. The slanted cutout in the frame is to provide a throughway for an arbor driving the hour strike fly below. Next a view from the top.

A view of the same bird detent as in the first photo above placed within the machine.

Orrery Output Drive

Parts for the orrery output gearing, fabrication began in October 2013.

 

We need the output gearing to perform two functions. The first is to reverse rotation of the final output shaft to the orrery from that present at the bevel and contrate drive wheels. The other is to obtain the correct gear ratio for the orrery. The period must be changed from mean solar to sidereal time. Parts count for this assembly, 51.

Rear Pendulum Mount 

 

 

Rear pendulum mount 19 parts. 

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