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Orrery, finish Jupiter gearbox, revise main orrery enamel dial ring  - October 2018

This month we complete the gearbox for the planet Jupiter. Then the main orrery enamel dial design is revised with a new design.



Here the Jupiter gearbox continues to be fabricated. In the first photo a hole is drilled in the upper gearbox plate to accept a pair of bearings. These will hold the four concentric moon cannon pinion set. Next the ball bearing pair is set within a pair of mounting rings and in the third photo, and attached to the upper gearbox plate. Next both the upper and lower plates are shown.


These are the first four of sixteen gears, these are the moon cannon pinions.


Four wheels completed.



The first photo shows one of the moon cannon pinions with a second wheel that is being attached using the staking tool in the second photo. The last two photos show seven wheels completed for Jupiter and its moons. Three of the original four cannon pinions now have second wheel attached.


These are the eight gears and cannon pinions for the counter shaft which will mesh with the wheels for the moons just completed.


Buchanan now begins the process of spoking out wheels. These photos show the scribing of the inner hub and outer rim circles. 


These two photos show Buchanan’s spoke scribing jig. This allows the accurate scribing of spoke layouts on wheels from six inches in diameter down to 5/8”.


The first photo shows a few wheels from blank to completion. The first three with with scribe marks; the third wheel with holes in the center of each wheel sector where the saw blade will be inserted, the fourth wheel after cutting out of all six sectors resulting in the spoked wheel. The rest of the wheels have an initial polish. The next photo shows the remaining wheels for the Jupiter gearbox.


In order to keep jewelling on all pivots that do not use ball bearings and keep them within the tight confines in the planetary gearboxes the standard jewels had to be trimmed in diameter.

Buchanan writes: Today, I have ground 10 more jewels to a smaller diameter, so, we have some spares. The other photo is the first trial fit of the sub arbour before fitting the jewels. The gear teeth are filled with polishing dust, they need cleaning.

I am pressing in the jewels now and adjusting the end play for the alignment of the gears. Then I will drill the plates for the sub arbour and the pillar holes.  


Buchanan writes: I have almost completed the drilling of Jupiter’s frames.  I have completed the depthing of the moon gears. I set up the gear train in the Hauser jig borer and adjusted the distance between the two sets of gears until they ran smoothly. Then read off the distance between the two arbours, The distance was 17.005 mm. but I could not remember what it should be, so, I went back to my spread sheet and the design distance was 17mm. I was rather pleased.

This demonstrates nicely why such a complex machine can be brought to reality - Buchanan’s constant attention to precision and detail at every step of fabrication.



Buchanan writes: I have fitted the cock that carries the Jupiter arbour which also acts as a centre support. Once the blank cock is mounted on the bottom plate, with its steady pins fitted, the top plate is fitted, and, the assembly is mounted in the jig borer. Then we centre the spindle on the upper bearing, using the dial gauge. The top plate is removed, and, the cock is drilled for the arbour, knowing that it is perfectly in alignment with the top bearing. It is a slow process but deadly accurate.


The first photo shows the inside area of the lower plate after a 3.13 slanted surface has been milled for the correct tilt of the gearbox mount assembly. Next the mount is shown attached to the lower plate. One can see the tilt in the lowest wheel compared to the wheel stack above, red arrows.


The first photo shows the beginnings of the moon arms as represented by the four solid disks above each of the corresponding drive wheels. Next is shown the clutch flanges stacked upon each other upon the top plate. These are individually screwed onto the threaded end of each moon cannon pinion and secure the moon arms.


The degree dial and its back plate are completed in the first photo and in the second photo the very small size of this dial is compared next to a men's wristwatch. This exemplifies the very fine engraving needed for the Jupiter and Saturn dial rings.


Buchanan writes: I have the moon arms cut out and the setting dial engraved. Next is the bezels and mounting the dial.  Then the skeletonising of the frames.


Buchanan uses a variety of files to smooth the edges of the moon arms. The next photo shows the various parts contained within each moon arm; these comprise the friction clutch assembly consisting of a friction C-spring and a lower and upper clutch ring case. This is then mounted into the moon arm. A fully assembled arm is shown above.


Another view of the individual moon arm. Even these small items are carefully made to the curvilinear frame design complete with a small plant spur on the neck. Other makers simply use a bent wire at 90 or just a plain rectangular, flat arm. Next the moon arms are mounted to the cannon pinion stalk.


The moon arms and their clutches are now complete.


Buchanan uses the broach to prepare the moon arm for the moon stalk. Notice the beautiful detail in the form of a small ferrule at the base of the moon stalk where it meets the moon arm.

The Jupiter gearbox is now mechanically complete.

Buchanan writes: I have the frame design for Jupiter complete. It is the same for both top and bottom frame this time. Very similar to Saturn’s lower frame but rather different proportions. I am also working on the art work for the orbit dial and having the last attempt at the angular relationship calculation for Jupiter.



The first photo shows the cutting out of the upper frame on the scroll saw. The remaining photos are of the lower frame.

Buchanan writes: Here is the beginning of the frames. You can see frame design getting cut through the paper into the brass below. Then onto the scroll saw. The small cock is a typical part that I will design on the run. I scribe the design straight onto the brass as most of the design is decided by the frame below.


These two photos show the rough out of the lower frame.  



The next two photos are additional machining of that frame. The third photo depicts the hand filing of the upper frame, using one of many dozens of filing buttons used to achieve a perfect curve. The last photo shows the lower frame in a semi-complete stage, center, with the upper frame in the lower left hand corner. The tweezers convey the small size of these parts. 

The frame details are now evident as well as the fine engraving on the degree dial ring. The ring is the size of a man's wristwatch mandating very fine detail for the engraving. The concentric wheels nest beautifully within the ring circumference.   


Deryck writes: These photos are: the machining down of the lower frame, the finished lower frame and the pillars turned and finally the reassembled frame with the reduced thickness frames and the little lower cock also cut down. I have also reduced the eccentric orbit bracket some more. This is not completely finished yet.



The first photo shows the computer design image used in the engraving of the Jupiter’s orbit dial. The next photo shows the beginning of the engraving process. Notice the brass blank has teeth around the perimeter; it is a recycled wheel from a prior project.


The toothed rim is cut from the rough-engraved blank and in the second photo the surface has been sanded smooth, revealing the dial engraving.



These photos show the orbit and degree dials finished with black dial wax to fill the engraving and the surfaces silvered. Then the dials are ‘dressed’ with their internal and external bezels, the latter having a knurled edge.  

The parts count for the Jupiter gearbox assembly is 89 parts.

Jupiter gearbox and its own little world of moons is finished.


Buchanan writes: Jupiter is finished. On to the Jupiter arm. I will first get a rough arm design, (I will reduce the Saturn arm design on the photo copier), then I can fit in the largest possible size gears and then we can go on to the final design once everything is on the arm. This arm has an extension out the back that carries the Saturn arm drive gears so will be rather different finally.


We now revisit the design of the main orrery enamel dial ring. In June of 2013 the initial design of the orrery dial was quite colorful to the point that it was decided that it looked too busy. A redesign was done to more closely look like a zodiac dial with the twelve houses but still containing all of the information on the orbital characteristics of the planets in the original. In reaction to the old design we went with a monochrome color scheme and the figures for the zodiac were taken from those that appeared on the planisphere.

Once we began to concentrate on the construction of the orrery we began to pay more attention to how this dial integrated within the rest of the machine and decided a change was needed. I wanted the new dial to more closely integrate with the tellurian dial immediately to the right and just below the orrery dial. This required the zodiac figures to be redrawn to match those on the tellurian dial as well as their color.

One may reasonably ask why the figures for the zodiac are different on the planisphere dial from that on the tellurian dial. The reason is that the planisphere dial was taken from a website for the design of planispheres that could be calculated to any latitude. Naturally I chose the latitude  for the city I live in which is very close to that of most major cities in Europe to the point that one could not tell the difference in the position of the stars on a five inch dial. That dial already had a set of zodiac figures which were copied for the artwork given to the enamellers in China. This was the first dial completed in early 2012. I thought that this was a very challenging dial given the figures, the multitude of stars and the many star designations that were depicted with calligraphic lettering and wanted to test the skill of the enamellers. The tellurian dial, made later that year, was based upon one found on Antide Janvier's clock. I immediately saw that these figures were better than those on the planisphere, but that dial was already made, and those figures were set against a dark blue background for the evening sky and star field representing the milky way and major stars and so had to be made in a single color and did not show as much as those on the tellurian dial which had a white background, the look of the individual figures were not as critical. Now that we are redesigning the orrery dial, the tellurian dial figures will be used.


Here we see all of the dial work used on the clock, the monochrome orrery dial is still present. The blue dial on the right is for the planisphere, the left dial was a dud.  

The first dial design was deemed too colorful to the point of distraction. The cartouches, while informative did not fit with the theme of an astronomical dial. It also had no stylistic connection with either the planisphere or the tellurian dials.

Planisphere artwork. Note the similar zodiac figures on this and the orrery dial below.

The second dial design substitutes the zodiac symbol for the same zodiac figures as that in the planisphere dial above but monochromatic theme. In this design we also incorporated the information on the cartouches for each planet (distance from the sun in astronomical units, orbital period in years, planetary mass in Earth units).

Tellurian dial artwork. Note the zodiac figures on this and the orrery dial below.

Current dial design using the same zodiac figures as that in the tellurian dial above and all of the planetary information on the prior designs.

The revised orrery dial design held next to the current tellurian enamel dial.  

The new design adds a bit more color and balance to the design of the dial work throughout the machine.  


Robert Crowder stands next to the astro-skeleton clock giving the viewer a good perspective on the size of the entire machine. Observers often think it is far larger than it really is. Mr. Crowder is one of the few outside sources for parts on the project. He has supplied the enamel dialing for the clock. The other parts being the custom cast bells, jewel and ball bearings and the Elinvar pendulum control springs.

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