Fabricate strike snails and begin strike hammer linkages - January 2014                     

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The first photo is a rendering of the hour snail. Buchanan had mentioned to me that he was thinking of a nautilus design, but I had no idea how far he was going to carry out this concept. Look at the additional four cutouts near the snail hub. This is what the natural nautilus shell displays when cut through with a saw, but is rarely if ever duplicated in a clock. Also the exterior steps exhibit the same organic design with the curved ends behind each of the snail steps. Next we have a rendering of the quarter snail. Again we have the additional cutouts near the hub as displayed in the hour snail. But more importantly, Buchanan chose to disconnect the number of spokes from the number of steps on the snail. In the example of the hour snail, it is natural to have each spoke meet with each step of the snail’s perimeter since there are twelve of these. However here there are only four steps. If we were to follow the same concept there would only be four spokes, a very unnatural nautilus. This design also makes both of the snails much more related to each other.


The first photo shows the brass blanks before fretting out. Next the completed nautilus designed snail cams. 


These photos show the heart shaped cam used to keep the snail in step within the petit sonnerie repeating mechanism. The first photo is the old solid heart shaped cam that has been on the movement until now. Buchanan has placed the skeletonized cam over the solid one for comparison. 


The first photo shows the heart cam mounted to the snail; next with that assembly mounted to the drive wheel in the last photo. Note the spring loaded follower wheel that acts upon the heat cam to keep it in step for the repeating mechanism.

The snail is now installed into the movement. Immediately we see a problem. Here the visual complexity of the clock is working against us. An ordinary wheel is fine to be ‘part of the forest’. But these snails are special and we need them to stand out. Several ideas were discussed. The first was some form of damascene on the surface, next having the edges knurled, next plating them in rhodium or rose gold, and finally using the EDM machine to put a fine matte finish on the surface similar to that which will be on the outside surfaces of the mainframe pillars. I like this last idea best since it will provide unity of design between these parts and the pillars. It also is one of the least labor intensive of the alternatives.


Now begins the fabrication of the strike lever and hammer system. This is the initial design schematic for the strike lever system. It will employ a grasshopper design using compound, articulated levers rather than the simpler, conventional lever type found on most movements. The grasshopper design allows for less friction and pressure forces on the operating parts. The second photo shows where the concepts for the impulse levers, in the form of allegorical roosters will be positioned as well as the background of the supporting frame and bell.


These photos show the pair of birds, the larger for the hour and the smaller for the quarter strike. They are in keeping with our concept for using birds in other parts of the clock movement. Those are for the escapement pallets, strike rack gathering pallets and the strike fly fan detents.

Next we explored the finish for the birds. We could go with brass, steel or blued steel. I ruled out brass since there is already so much brass colored material in this vicinity. Steel was rejected for the same reason. Blued steel was chosen since we are using this same finish for the strike levers and racks, circled area. The blue color choice will complete the connection between those components and this final extension to the bells.

The strike levers are now being fabricated. Note the file in the background of the first and second photos. Buchanan aligns all of the same sized levers together and uses the file for final shaping thus achieving a uniform set of parts. The parts are initially cut out from a steel sheet in the same jewelers saw used for the rest of the flat stock used in this movement. The third photo shows the eight completed levers. The next photo shows the three roosters which will serve as the impulse levers off the strike train’s drive cam carousel. The last two two photos show the roosters placed into context of the levers.

The levers are now being machined to accept the spacers and roller bearings upon which they will pivot.


The levers are now positioned into the movement for the first trial fit. I like the way these vertical curvilinear levers provide juxtaposition against the straight horizontal arbors.

The levers begin to be assembled. First Buchanan has to make about fifty custom screws. The fourth photo shows the assembled hour and quarter strike lever sets. After these are tested for fit and functionality the brass spacers are turned for their final decorative profiles.

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