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.
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.
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
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
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
nicely why such a complex machine can be brought to reality - Buchanan’s
constant attention to precision and detail at every step of fabrication.
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
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.
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.
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,
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.
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
The first photo shows the cutting out of the upper frame on the scroll saw.
The remaining photos are of the lower frame.
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.
The Jupiter gearbox is complete. The only remaining
item is to decoratively turn the frame pillars.
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.
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. So 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.
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.