Finish power reserve indicators; prep work upper frames - April
B now begins the fabrication of the steel
levers for the reserve power system that will be used to move the indicator hands. One end
will have a cam roller following the profile of a snail, third photo, with the other
connected to the indicator hand. The first two photos show this lever, again with the
signature ivy design. The last two show the lever in position next to the snail.
Eventually these levers will be polished, chamfered and chiseled in the manner of Breguet
and then heat blued. Notice these are handed, that is one pair is left while the other is
right oriented. This was done for aesthetic reasons. In the center of the lower frame is
located the planisphere, so it will be appropriate to have a mirrored pair of sector gears
with their counter weights on either side. The last two photos show the full rotational
angle through which the snail will turn and the lever will move.
A few photos of the long, thin arbors
now with the sector gear and its associated indicator hand sector gear and arbor attached.
Next begin the counterweights which
will be used to keep the indicator lever seated against the snail cam. Normally one would
expect a simple leaf spring to be employed. Here we wanted something more visually
appealing. These weights also allow us to tie their design in with those of the
counter-weights in the time train dual remontoire. They will also give visual movement as
the movement is wound, something that a spring would not.
The second to last photo
shows the completed 'front end' of the power reserve indicator system. One will readily
see the counter-weight rise as the barrel is wound. The last shows the rear end where the
following lever contacts the snail cam as well as the winding stop assembly.
A few over all views of the completed lower section of the movement. Note
the architectural detailing of the frame corner in the first photo. The rest show off the
decorative great wheels with their epicyclical maintaining power systems. These will be
the last time we will see the lower assembly before the addition of the rough upper frame
B now begins the task of transferring the
wheelworks from the temporary acrylic frames where they now reside and have been beginning
in March 2008 into the permanent metal frames. First he has to mark out the positions from
the acrylic frames onto the mill machine for final drilling into the upper frame metal
pieces. These acrylic pieces now will serve as the template for the final positioning of
the wheel works. The first photo below is the center sub-plate that resides between the
two main front and rear plates. The markings show the hole coordinates. Next two photos
show the main plates.
B uses the digital plotter on the mill to
pick up where each hole is on the plastic frames. They now serve as a template for the
mill to be able to later drill holes in the exact positions in the final metal frame
parts. Obviously this task needs attention to detail to avoid any mistakes. Special
attention is paid to positioning of the plastic to metal parts. The first photo shows the
jig that is attached to the mill bed and will be used to accurately position first the
acrylic and then the metal parts through the use of positioning pins. Once the acrylic
frame is secured each hole must be located and its X-Y position recorded into the mill.
First the exact center of each hole must be located using a feeler gauge accurate to 1/100
millimeter, second photo. Once this is found the position is recorded into a digital
plotter, third photo. B does not use any computer aided machining, i.e. CAM. The digital
readout acts as a very accurate way to position the mill head, but the machining is not
controlled by computer.
To double check the hole positions the
original acrylic frame components are used as a template and are placed over the metal
pieces to be drilled. The positions of the holes on the acrylic pieces are located and
read off of a digital plotter. Next begins the drilling. For moderately sized holes the
first step in this process is to drill a pilot hole, then the full sized hole and finally
a reamer to finish. Larger holes are drilled with a small router bit mounted to the mill
head, sixth photo. The last two photos show the use of a counter-bore to create a
counter-sunk hole for the installation of a bush.
The next photos show how the larger pinion faces will be finished
off. One does not want a simple flat face on a large pinion as this makes the part look
clumsy and larger than it would otherwise. Note also the very high pinion leaf count; and
is typical throughout the movement. The third photo shows the final machining design
of a typical wheel collet. Each collet requires five separate steps to achieve the final
The roughed out upper frame pieces are fitted to the completed lower
frame and checked for fit. The remontoire differential is the first set of movement parts
to be inserted within the upper metal frame components.