Remontoire fly; escapement lead off bevels,
pillar bases, pillars; fly carriage designs, April 2008
Here begins the fabrication of the cam drive wheels, fly fan and
escapement drive bevel wheels.
The bevel blanks are checked for fit prior to cutting. Next a finished
bevel drive wheel is matched against its mating fly drive bevel wheel that is still from
the wood mockup. Next the rest of the complicated bevel and regular wheel systems that
will drive the remote fly and two escape wheels from the wood mockup are checked for fit
(upper five wheels).
Fabrication of remontoire main supports. In addition to containing most of
the dual remontoire the upper surfaces are made to become the bases for the main columns
that will support one of the remontoire fly fans. These will be in a classical design.
Several drawings and style for the fly fan columns were considered. It is
difficult to see how a column might be without actually having a sample, so several styles
were produced and sent to me for approval. This is a very important style element of the
movement as it will appear in many places, and once chosen must remain consistent for all
vertical columns. None of the five finalists as received was just right, but I did take
the capital and base features from the far right column and combined them with the plain
surfaced bulging-center style of shaft on the column second from the left. Last photo
shows two samples upon the finished remontoire base.
We now begin the remontoire fly fans. The fabricator produced a
drawing keeping with our curvilinear "Condliff" style, complete with spurs on
the convex outside curves. Added fretting on the main and subsidiary pillar brackets
complete the picture. The third rendering shows two options for the lower main fly
bracket. The upper half has an open diamond while the lower would be a cross with a
central hole for the fly drive arbor to pass through. I chose the diamond design. With the
simple spur on the left . The next photo is the fly as originally produced on the mockup.
One can see the many flourishes that evolved from that design in the third photo, still in
wood, but with all of the features. This is then re-inserted into the mockup to see how it
contributes to the whole before metal is cut.
The large circular ring is actually an internally toothed gear that will
engage the two fly fans. B uses a custom made fly cutter device to be able to directly cut
these teeth. The cutter is mounted to a narrow boom which is then fed directly into the
inside of the ring. See also video below.
This photo shows the final material chosen for our screws to produce what
I call 'electric blue'. The two screws to the left are antique screws for comparison. This
color is commonly found on watch components and on some antique American made back vault
time locks. It is not a color that is generally used by classical clock makers where the
deep purple color is preferred. I wanted the screw colors to stand out more. We will have
four primary colors with brass being the most prominent followed by silver for arbors and
ferrous flat stock, the blue screws and finally the red pivot jewels. The search for the
right heat-blued color was quite difficult. The silver steel that the fabricator had on
hand for screw stock did not blue well. It mostly came into a dull gray-blue. It seems
that the modern metals available lack some component that antique screws had, all of which
blue up quite nicely. The steel stock also had to be available in various rod sizes to
accommodate the large variety of screws that need to be made. Another factor affecting the
perceived color is the configuration of the screw head. Classical Philister head also
known as cheese head screws have a flat top surface. Once polished, as all screw heads
will be, this surface acts like a mirror, and like a mirror, only reflects light at the
complimentary angle at which it strikes the surface. Thus the true blue color was
prominent at only a few limited viewing angles and never from directly in front where most
needed. A very slight curvature solved this problem, and while an unwanted departure from
the classical cheese head design, was necessary to get the desired visual effect.
It took us about six months of trial and error before we
found the correct steel formulation and one that was available in the
variety of sizes needed for the project. This is grade 1045 steel. 1045 is a
medium tensile low hardenability carbon steel generally supplied in the
black hot rolled or occasionally in the normalized condition, with a typical
tensile strength range 570 - 700 Mpa and Brinell hardness range 170 - 210 in
either condition. Characterized by fairly good strength and impact
properties, plus good machinability and reasonable weldability in the hot
rolled or normalized condition.
One of the key aspects of this steel is the carbon content. Many "off
the shelf" screws are designed for high strength and often corrosion
resistant applications. This type of steel typically has a low carbon
content. Carbon is necessary for the right color of blue when heated to 563 degrees,
. There is a tight variance envelope here. another 5 degrees
and the blue begins to turn more pale than we want.