Strike and repeat control assemblies, main strike strike fly fan detents - February 2011                         

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Shown above is a strike detent assembly. There are two of these, one for the quarter and one for the hour strike trains. Each are connected to their respective racks; which will control the duration of the striking sequence of each train. At this point it looks awful as it appears to be merely 'stuck on' the side of the lintel's end. The lintel as well as the detent frame will be machined to correct this. The encircled area in the last photo is the detent and is shown below. A second detent will be attached to the left side of the horizontal lentil to control the hour strike train.

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The detent is enlarged above. This device is what will release and then engage the strike train fly fan assembly whip (the long, straight piece seen slightly blurred in lower right hand corner); mediating the duration of the strike sequence. Note that we continue our bird design carried through from the escapement and the seesaw rack gathering assemblies. The red area will be the bird's jeweled beak. All of the various components making up the strike system are currently fabricated in brass. Once the system is thoroughly tested and debugged, these components will be re-machined in steel and the majority of the components blued.

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Buchanan now draws out the rough outlines of what he believes will be the component layout of the strike control system. The first photo shows the pair of mounts holding the rack fall-arresting fly fan assemblies. Also shown are the strike racks and the hour fly fan detent. The second photo shows the beginnings of strike and repeat initiator; also containing a pair of small fly fans. All of these fly fans provide cushioning of the various strike components as they are activated. But more importantly, (remember the number one rule of this project - visual impact), there will be a cascading effect of these flies; beginning with the uppermost and smallest fly connected to the initiator, then proceeding downward to the strike racks and finally to the release of the strike train fly fan mounted to the base of the movement frame. This cascade of events leading to the release of the strike train fly should last approximately two seconds. Plenty of time to catch the viewer's attention.

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The strike initiator cam has four arms with jeweled rollers on each. This will be mounted to the same arbor as the quarter strike snail. This can be seen on the last photo with the rough-machined snail in the foreground.

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Shown are a few of the various components of the strike/ repeat initiator. Note the machined collar, third photo, which attaches the pinion to the wheel. This component is out front; in a prominent place so we do not use the conventional method of simply attaching the pinion adjacent to the wheel hub. Another example of Buchanan's uncompromising standards. The solid wheels will later be spoked.

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The various parts are assembled and the assembly is shown positioned approximately where it will reside within the movement.

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Finally this month I had completed an article to be published in the April issue of the Bulletin of the National Association of Watch and Clock Collectors (NAWCC) titled Halfway Point for the Astronomical Skeleton Clock. This describes the progress of the clock up to August 2010 by which time construction of the movement had been underway for three years. Shown is the galley of the rear cover for the issue. This makes the second rear cover article published in the Bulletin, the first having been published August 2007 describing the scope of the project, its initial design and mockup work. You can read the on-line versions of these articles here: Original presentation paper on the Astronomical Skeleton Clock. and Halfway point for the construction of the Astronomical Skeleton Clock, Year Three .



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The first video shows a test of the quarter strike  sequence. The second shows a close-up of the gathering pallets used to raise the quarter strike rack. As with everything else in this project we chose a much more visually fascinating way to do this. A conventional clock would have a simple single or double bladed pinion to raise the rack in conjunction with a rack hook to keep the rack in place. We use two jeweled pallets, a rocker arm and cam to drive the rocker.                     


Here we test for the first time the quarter and hour strike sequences. There are still many parts to be added to for these components to not only strike in a conventional manner but to also posses a full repeat on demand function.

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