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Calculation and fabrication of remaining cam contours and spokes.

Note that the format of this section of the web site is designed for the newer wide screen monitors, those using the conventional 3:2 ratio monitors may need to move the horizontal scrollbar at the bottom of the screen to see the entire page.

I have asked Buchanan to provide what I call a 'forensic' report. That is to record his observations as he goes along. I will provide the .MP3 audio file for each segment but just in case your security settings will not allow you to open this file I have also transcribed each session. My additional comments will be inserted into the text from time to time and this will be in red text. Buchanan refers to each photo by the number of that photo which can be followed by each photo above the captioned text. The .mp3 audio file will appear in blue text.MP3. Click on this text and you can then follow along with the audio file by scrolling downward through the photos as they are narrated one by one in the voice of the restorer.

Pouvillon-36-000.MP3. Photo 36 001. We have the one year arbor with the two cam blanks fitted for the sunrise/sunset shutters. In the upper portion of the cam you can see the two levers resting against the peripheral edges of the cam blanks. Photo 36 003. We have another view of the two cam blanks and the operating levers resting on the upper edges. Photo 36 004. Here we are marking out the seventy three spaces on the cam blank prior to transferring our test measurements. Just below the steel ruler between the ‘2’ and the ‘3’ we have a blade inserted into a slot against which we index the seventy three teeth of the one year wheel. This gives me my seventy three divisions. You’ll notice that the scribe lines are off-center to the center arbor. This is because the two black levers that read the cams are actually mounted off center to the center line of the arbor. If you refer back to the earlier photographs you’ll see that drop down pillar and each operating cam is located on an arbor projecting from each side of the drop down pillar. So I’ve put a bush on the center pivot of this cam to give us the correct spacing. The line is straight because the arc of the lever is at right angles to the axis of the one year cam; whereas the arc of the equation of time cam, the pivot was parallel to the one year arbor, which meant that we had to have a curved line to give the correct positioning of our measurements.

Photo 36 005. We have the fully marked up cam. What I’ve done is I’ve marked out every alternative tooth so we’ve marked them out one, three, five, seven, nine and so on all the way around it just gives us a little clearer spacing. On our error correction chart we still will do the full seventy three readings to check our errors. Photo 36 006. Here we have the beginning of the error correction chart; we have three sets of columns to fit in all our readings. When we go to the left hand side of the page the first column is the tooth number of the one year feed wheel or the star wheel with the fancy shaped spokes numbered one through seventy three. The second column gives us the actual time of sunrise for each one of those seventy three positions. Then the third, narrow column which at this stage is empty is my ‘test one’ column. I’ll show you in the following photographs how we arrive at the readings for the test one. Photo 36 007. Here we have a caliper lifting the sunrise lever. The bottom has a hook which attaches to the one year arbor, and we adjust the thumbwheel to open or close the caliper until we have the correct reading on the sunrise shutter for any particular day. Once we have this reading correctly, I’ll then take the caliper and transfer this measurement onto our cam blank.

Pouvillon-36-011.MP3. Photo 36 012. Here we have the sunrise/sunset dial removed from the mechanism. When attempting to set the shutters to mark out the cams I found that the dial was virtually illegible so we have proceeded to clean it up. Doesn’t this silhouette look a bit like a bear cub’s face? The second photo shows this dial cleaned up. Pouvillon-36-014.MP3. Photo 36 014. Here we have the caliper with the hook end around the center arbor of the cam and the upper notch section which holds the sunrise/sunset lever is now on scribe line ‘1’ and we make a scribe mark on the number ‘1’ radial line.

Photo 36 015. One can just the scribe line across the number ‘1’ radial line. Photo 36 016. Here we have a slightly clearer view of the first scribe mark on the sunrise cam blank. Pouvillon-37-000.MP3. Photo 37 001. We have a cam blank for the sunset shutter dial. You’ll notice that we have a series of radial scribe lines offset from the center to take into account the off center mounting of the reading lever. You’ll notice we’ve also numbered each radial line according to each step of the annual ring.

Photo 37 002. We have the cam cut out initially. The station numbers are every second scribe line and the outer ring numbers are the number of minutes error on the actual dial once the cam is installed. Photo 37 003 is the cam blank and also our error chart. If you go to the left hand side of the first page you’ll see in the first column we have the year wheel tooth number; in other words the number of steps to rotate the cam around one year. In the second column the target value is what we want the hand to read on the dial for each station. So on station one it should be 7 hours and 44 minutes. When we actually performed test one in the third column, you see that it was 7 hours and 30 minutes which means we have an error of approximately 14 minutes. This is then noted on the cam blank and we remove metal according to the error. And then we install the cam blank into the clock a second time and we test again. So if you look at our first column it should read 744. It read 730 we have an error of fourteen in test one. In test two it has been reduced to twelve. This continues until we are within our desired tolerance. Photo 37 004. We’ve now proceeded to test five using the same method.

Photo 37 005. We can see we now have certain sections of the cam that are up to accuracy and a small error remaining on certain portions which we continue to remove. Photo 37 006 is the final is the final shape of the cam and you can see the original blank size to get some idea of the amount of metal removed in the filing and testing. Photo 37 007 is the sunset cam and the equation of time cam.

Photo 37 008 is the completed cam and the seven tests which if you take 73 stations times seven tests, it means on each cam we have performed 511 test files until we’ve gotten the desired accuracy. Remember that this exercise was done for four of the five cams in the annular cam pack.

Pouvillon-40-001.MP3. Photo 40 001 shows a base pillar of the main frame of the clock with a cutout to clear the new count wheel or the count wheel, I believe, was fitted after the original pins mounted in the face of the strike wheel. Photo 40 002. Another photograph showing the cutout in the splayed base of the rear main clock pillar to clear the count wheel. And, of course, in the foreground we see the blue pins that are now unused on the strike great wheel. Photo 40 003. We’re trying to show here provision made in the pillar, actually a horizontal beam, going across the base of the clock to clear the pins projecting from the face of the strike great wheel. This horizontal support beam is made from a different material from the rest of the steel used in the Phase One clock frame. It looks, in fact, to be plated and is identical to the material used in the small pillar located behind the fly fan for which we have found no function for at this time. see Photo 47 010. As found, someone, whose crude work was obviously not Pouvillon’s, had tried to use that pillar to trip the Easter calculator on a daily basis from the strike count wheel. The entire design was wrong, as the calculator is tripped annually. Pouvillon had added these two plated components to the clock at a much later date.

Photo 40 004. We need to look carefully at the darker portion on the right hand side of the picture just below the notch in the count wheel where you can see a reflection in a frame showing an undrilled pivot hole, or a mark on the frame corresponds to the front frame where Mr. Pouvillon has placed a pivot and on the rear frame it has remained undrilled because it has never been used. Photo 40 005. Here we can see a better view of the center punch mark in the frame member right in the center of the photograph. Photo 40 006. Another pivot point that is undrilled on the rear frame. I believe the front and rear frame were made in the traditional manner where both frames were clamped directly onto each other and marked out and cut out. But, of course, this point on the rear frame has no pivot so it was left undrilled, only marked. In blue circle.

The first photo shows the length of day/length of night cam. Since any 24 hour period can only be divided between the day and night, these two dials can be read off this single cam. The next photo shows one of the cams controlling the sun rise/sunset shutters on the log book page used to test and cut the cam to its correct profile. Unlike the length of day/length of night function, the shutters each need a separate cam for the sunrise and the sunset function. See video below. The third photo is the second cam for the shutters.

The next photo shows the three cams mounted on the one year step arbor. The equation cam is hidden by the larger, first shutter cam. One can see the three levers acting upon the surfaces of these three cams to perform the length of day/length of night dial function as well as the raising and lowering of the sunrise/sunset shutters. Next the kidney shaped cam is being crossed out on Buchanan’s scroll saw. A similar procedure was done on the remaining cams and the result is shown in the next photo.



The four photos above show the beauty of the cam pack. It holds a central position within the clock and the fact that it is 900 to the rest of the movement only accentuates this part’s importance. We have tried to reverse-engineer this assembly as close as we could to what Pouvillon would have done. It completely fits into all existing holes and spaces without any additional alteration to the original artifact. Given its visual appeal one could see how this part ‘went missing’ sometime in the past; perhaps when the clock was in pieces at the charity shop, see biography at the beginning of this project.


Pouvillon-42-010.MP3. Photo 42 010, last photo above, is a photograph showing the cam pack assembled into the clock we still have to fit the snail, finally, that will trip the Easter calculator. Photo 42 012. Another view of the cam pack and the operating levers which you can see resting on the top of the cams. Photo 42 013. Another view if the cam pack fitted to the clock.


Shown here are the diagrammatical sketches of the lunar dial and the Planisphere dial. We will see in latter documentation that these two complications had to be devised at the same time as their feeds are conjoined.


Pouvillon-44-000.MP3. Photo 44 001. Here is a view of the feed that drives the main orrery. Of interest to note is that the bevel gear fitted to the second arbor driven off the strike great wheel is only pinned to the arbor, there’s no flange on the arbor for it to but up against as in all of the parts of the clock pertaining to the actual time or strike train, as was done in all of the Phase One construction, see blue arrow. It’s meshing with a second bevel and a vertical arbor mounted on a cock. This cock is interesting because it supports the planisphere dial. We can also see the pinion just above the vertical drive bevel that actually drives the planisphere. This pinion is separate to the actual bevel gear and I am inclined to think it is a later addition, see white arrow and Photo 45 002, below. Photo 44 002 shows us the universal supported on a cock on the second frame pillar and this is to provide a ‘kink’ in the vertical arbor to clear one of the time train arbors. The cock that supports the arbor just below the universal joint also carried the lunar dial. Also note the circled area where this cock is joined to the Phase One cross frame pillar. It is done by having a flat filed onto the frame pillar with a simple rectangular metal piece fitted. There is no effort to blend this piece in as would have been the case if this piece was conceived as a whole in the Phase One design.


Photo 44 003 is another view of the vertical arbor and the bend introduced by Mr. Pouvillon to bypass the time train arbor. I think that had he planned this addition initially, he would have made a slight change in the size or position of this time train arbor or also changed the position of the strike arbor where the bevel gear drive is to prevent a misalignment or an obstruction that is causing him to use a universal in this drive. Photo 44 004. Another view of the lower orrery drive bevels not shown. Photo 44 005. A picture of the universal joint halfway up the orrery drive arbor.

Some more conclusions as to sequence of construction from the restorer. All these photos evidence the vertical drive to the orrery. As one can see the two cocks that support the vertical arbor are the minimum required to fulfil their function. Both cocks carry a later complication. A look at the orrery platform will show that this has no provisions for latter projections that support the mystery dial. In other words after the main movement, (Phase One), the orrery was next. No other complications could have existed without it and all are attached in some way or driven from it. When the clock is finally restored I think we will do a sequence of assembly photos to prove this point.


Pouvillon-45-000.MP3. Photo 45 001. Not shown. We have the planisphere mechanism mounted on the cock supporting the lower end of the bevel drive to the orrery. Photo 45 002. We have a view from the opposite side of the planisphere mechanism. We can see the pinion on the vertical arbor driving a gear wheel on a second arbor. You can also see that it is carried by a cock screwed to the cock mount carrying the bevel gears. And, of course, this arbor carries the drive up to the lunar dial. Photo 45 003. Here we have the drive consisting of a train of three small gears to the lunar dial. It’s also mounted on a separate, attached sub-cock and is part of the lunar drive train. If we remove the lunar drive train then there is no support for the upper end of this arbor, the second vertical arbor, and the planisphere won’t operate unless one mounted a single cock on the upper lunar dial support to carry the upper end of this arbor. It’s also a question as to why this arbor is so long. I think that both the planisphere dial and the lunar dial were constructed simultaneously. Otherwise there would have been parts discarded if one complication was made individually before the other.

A few more conclusions as to sequence of construction from the restorer.

The planisphere, from the construction point of view seems to be interrelated with the lunar dial. In the first two photos you will see the 24 hour arbor is pivoted, at the lower end, in the planisphere frame and in the third photo, the upper end of the 24 hour arbor, in the lunar frame cock. Now which came first?

The 24 hour arbor is required for both dials. There was either a temporary cock for the top or bottom pivot or Pouvillon built them simultaneously. This is the first time this question has presented itself. So Pouvillon is able to integrate two complications as we have said before, but this is the first time we have seen it done between complications. Up until now each stage of construction is a stand-alone unit. If you remove the planisphere the lunar dial will not function and if the lunar dial is removed the planisphere will not function, although a simple cock would solve the problem in both cases.

The kinked universal drive to the orrery is, I think, a clear indication that he had not planned to fit the orrery originally. This means that the orrery was not a planned part of the main clock frame containing the time and strike trains, what we call the Phase One sequence of the clock’s construction. The comports with our earlier observations that Pouvillon first created the steel-framed two train clock as a stand-alone unit before ever conceiving of using it to create his astronomical clock.

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