mockup for perpetual calendar remontoire, begin calendar dial drive wheels
- December 2014
Here is the initial
mockup for the subassembly that will contain a perpetual calendar module as
well as the spring remontoire which will control the power feed of the remaining
calendar functions. Shown
are the main drive wheels. The mockup
measures 8.25 x 4.5 x 2.75 inches (210 x 115 x 70 cm).
The lowest wheel is driven by the
celestial train and represents the last wheel in the clock at present in the
calendar drive. This revolves 1/4 turn per day. It is geared 1:2 to the
centre arbor. This arbor makes 1/2 rev per day and is the output arbor from
the remontoire which is between the lowest and centre arbor. It will have a
double arm. The ratio between the center arbor and upper arbor gives
slightly more motion than is required to rotate the date hand from the 28th
to the 1st.
These photos show the components of the spring remontoire which will
feed power to the calendar mechanism once per day. The third photo shows the
spring in its barrel.
The completed spring barrel
gives torque in both directions.
he barrel arbor is connected to a four pinned cam looking like
a lantern pinion as seen in the
the pinion which acts to release and arrest the remontoire detent arm.
That arm is shaped in a curvilinear pattern not just for looks but in case
should it become jammed against the cam, it has some ability to flex, thus
avoiding damage. The third photo shows a pair of ratchet pawls behind the
first of a pair of wheels to the left. One allows the wheel to only rotate
in one direction while the other is involved with locking the wheel’s fly
fan. Each wheel in the pair is designed to operate sequentially and
independently of each other. One rotates clockwise and the other
counterclockwise. Each is used to operate the perpetual calendar in either
forward or reverse.
The perpetual calendar
module which was fabricated last month is now mounted to the front of the
calendar drive plates. The interior contains the calendar drive and
remontoire. This is only a proof of concept model. The perpetual calendar module
will later be placed in a location apart from the rest of the calendar drive
Driving the perpetual calendar module.
These photos show a solution to the possible problem of the remontoire
jamming. The remontoire releases at a certain inherent speed dictated by its
drive spring and if one cranks the celestial demonstration function too
quickly, it could overrun the remontoire’s speed causing a lockup or barring
a clutch (which we will have) damage to the mechanism.
Our solution is if the
rotation becomes too fast the mating lantern pinion to the remontoire detent
arm will automatically retract, thus freeing up the detent. However, this is only one interesting feature of
this contrivance. Should the remontoire arm become jammed for any reason the
rotation of the remontoire spring barrel under the normal course of its
being loaded by the celestial train will also cause the pinion to retract,
thus freeing the jammed arm automatically. That arm is also specially shaped into an ‘S’
pattern to allow it to slightly flex should it become jammed up against the
lantern detent pinion preventing damage to it and the pinion and allowing it
to be freed up upon retraction.
In the first photo the arbor
that has the cam attached to its end is shown in the retracted position,
green arrow. A pin is attached perpendicular to this arbor and is shown by
the red arrow. If the demonstration drive runs faster than the speed of the
spring driving the remontoire, the pin will slide along the radial slanted
groove pulling the pin backward and therefore the arbor inward. This will work in
either direction. When there is no overdriving of the remontoire, the pin is
at rest in the 12 o’clock position and the arbor is fully extended outward
allowing the cam to fully engage with the detent arm, second photo.
The video below
shows this succinctly."
The remontoire safety device.
A front, rear and side
view of the completed mockup for the perpetual calendar module and drive.
Notice the two independent fly fan governors for the two independent
bi-directional drives associated with the demonstration being able to be
shown in forward and reverse. This model is approximately three times the
size that the final module will be.
Demonstration of the calendar drive
This drawing shows a
bit of what was described above concerning the layout the calendar
mechanism. Here the perpetual module has been separated from the remontoire,
calendar and the input drives.
Here we have a front
and side elevation drawing of the bezel and dial cluster. Next a log of the
wheels needed for the perpetual module and drive works. The dark box
contains the various cutters that will be used to create the various tooth
profiles needed. So far there are twenty one wheels, excluding those needed
for the actual dial indicators.
Now begins the
fabrication of the calendar in metal. First the rough wheel blanks cut
directly from the sheet brass are stacked up like a set of old coins. Next
one of the cutters used to cut the teeth and next the completed set of
toothed wheels before spoking out. The scale is 1.5 inches or 4.0 cm.
Next one of the brass
blanks upon which the calendar system will be mounted is installed. The last time the clock had large brass plates on its structure was in
January of 2011, but a good photo of this is December of 2010.
plate has two aligning pins that fit into two blind holes in the
pillar behind the plate.
n elegant knurl knob and decorated shaft will hold
the calendar module to the rest of the movement, second photo. The knob is
positioned away from the wheelwork that is directly below to avoid injury to
those parts when manipulated. Removing this one retaining fastener will release the entire
calendar assembly from the rest of the movement. We will replicate this type
of modularity with the rest of the major complications.
Here Buchanan begins to
make a contrate wheel, next the beginnings of another complex-shaped
The last photo shows the completed contrate wheel and rough potence for the calendar drive.
Here we see how
Buchanan uses a jig to transform the rough potence into the contours of a
complex part. The outside diameters of the hard steel tubes, also sometimes
called filing buttons, supply the
pattern for the softer brass material. Hand filing then can create a near
perfectly round profile using the tubes as a guide.
The completed lower pivot for the calendar drive. Later the contrate wheel
will later be spoked out.
Here we see Buchanan fabricating the upper
pivot for the drive to the calendar. I included this to show that this part
which is an angular shaped part is actually cut from a piece of brass rod
stock rather than what one might expect, a bar stock.
The completed, but as
yet not yet embellished upper pivot showing the angular shape. The second
photo shows the intersection of the sidereal and calendar drive arbors. The
calendar drive is now in place.
Now begins the
fabrication of the calendar module. The first photo shows some of the arbors
that the wheels which the individual calendar dial hands are be attached
will be mounted. These arbors are attached at only one end and are called
dumb arbors. This is necessary as the free ends of the arbors are
located in the center of each dial ring. The drive illustrated in the
previous photos is shown.
The first photo shows how these dumb arbors
are arranged in the middle if each dial. Next a side view. Notice the large
amount of space between the dial drive wheel and the dial. This is necessary
because the perpetual calendar module will be located right behind the
uppermost dial in the dial cluster.
These two photos show how
the entire calendar mechanism will be positioned within the machine. It
nicely fills in what otherwise was a rare piece of open space. The front
plate holds the dial drives and perpetual
module. The rear of the front plate as well as the rear plate behind
contains the balance of the calendar mechanism; the remontoire, fly governors
and associated, reversible drive gearing. It is Christmas time and Buchanan has put on a pair
of Santa hats on the two pendulum balls. See video below
Merry Christmas, Happy New Year!
Here the wheels undergo a depthing operation. Once the optimal depth of each
wheel is determined those measurements are transferred onto the brass
plate where the wheel arbors will be planted. The third photo shows a view
through a microscope where the intersection of the two scribe lines marks
where the plate needs to be drilled.
These two photos show a
new set of screws that needed to be made for the smaller wheels. These
wheels are the smallest yet made in this project. The matchstick is just
over 1.5”, (4 cm) long and the diameter of the screw head in 30 thousands of
an inch in diameter.
Here the wheel collets
are threaded using a small tap. The scale is small enough that it is turned
by hand by the knob located above the jig.
At this scale it was
decided that the cheese head style of screws were not appropriate and were
changed to a countersunk oval head type. The first photo shows two loose cheese head
screws to the left, with one of the new style screws installed on the wheel.
The match head gives an idea of how small a scale we have started to employ.
Parts of the calendar work, the perpetual module in particular, as well as
parts of other complications will be on the scale of pocket watch work. This
will be most evident in the orrery.
completed wheel works for the calendar dials are shown both in pieces and
assembled. There are 46 parts that comprise this subassembly.
The first photo shows
the spoke scribing jig Deryck uses to correctly divide the number of spokes
to be cut. The wheel being spoked is just over 0.5” (1.5 cm) in diameter.
Even such small wheels are spoked out, no short cuts.
The oval head
screws look good on the finished wheel, next a few completed wheels.
These photos show the
difference in weight from the wheel blank at 19.3 grams to the spoked out
wheel at 3.2 grams. This is an 83.4% reduction and a testament to Buchanan’s
fine wheel rim and spoking.