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Continue Sun / Moon rise set, dial hand drive assemblies and differential frame  - May 2017



Buchanan writes: I have made the bearing tube for the drive to the moon great wheel. There will be another shorter tube on the other side of the main plate. There is no place for a conventional cock. The two steel flanged bushes are the bearing carrier for the slant wheel arbours as well as part of the setting clutch. It will be more self-explanatory when they are complete. These bushes are a stiff rotating fit in the frame and carry the stationary drive wheel to the rotating wheel train on each slant wheel. The present stationary drive wheel will be replaced with a wheel with a contrate wheel on the side that will be driven by the setting square.



Buchanan writes: I have cut the new double wheels as well as the two right angle wheels that make up the moon phase setting mechanisms. The stainless steel bearing tube will be friction tight with a clutch and the setting wheel will rotate the double toothed fixed wheel to set each moon correction period. I will send a video as soon as I have one operational. The square brass block is just a mock section of the final frame.


Buchanan writes: I have made some progress the last two days. This is the rear drive to the slant wheels. A lot of little messy details. Collets and frame bearings have to check clearances all the time.



Buchanan writes: The intermediate wheel on the rear in feed gear train is complete as well as the two matching wheels on the rear frame. I have also completed the transfer arbour that takes the drive through the back main plate. Next is pitching the output wheel on the slant wheel assembly. This will take a bit because I need to fix the slant wheel frames and a few other details.



Buchanan writes: In photo 767, (first photo), I am finding the correct position for the new bearing. I have the two wheel meshing and then glue a reference boss onto the plate in the correct position. This is held in place by an extended rod through the frame bearings.  I then set it up in the jig borer, photo 764 (second photo), exactly centre to the machine spindle. Once the plate is clamped onto the table, I knock off the reference boss and bore out the plate for the bearing. The bearing is half in the plate and half in the boss photo 766 (third photo). This boss will hold the large wheel in photo 768, (fouth photo), and also the curved drive arm for the last slant wheel, so it needs to be rigid.

Now I can set up the frames with a rod through the two frame bearings and this boss and then I can fit the steady pins into the flange on the pillar. After that there is one last bearing to fit on the in feed arbour and we will have a drive right up to the moon arbour.


Buchanan writes: We are on the way to the moon. I cut two more gears. One a 16 tooth pinion that I missed on the main gear cutting session and the first contrate wheel for the second last moon arbour. On the final drive where there is a kink in the arbour, do you want a bevel wheel drive or a universal joint like the Pouvillon. The contrate wheel is 5/8 inch 40 teeth and the pinion is 3/16 inch 16 teeth.

The Pouvillon is another astronomical clock from my collection Buchanan had restored for me.


We now turn to the fabrication of the frame containing the set of variable differential wheels as well as securing the front plate with the readout drive assemblies for this module.



Buchanan writes: Here is the mock up frame. I think I can reduce it in thickness a bit more. There are still the moon phase set of right angle gears and two more wheels at the back end to come. Also a small sub frame to support the back end input wheels. This will be mounted on the flat pad below the outermost slant wheel bearing. The frame design will be refined but this is the shape that seems to present itself. It can only get better.

Here Buchanan has made a frame in the same curvilinear, ivy leaf style as in the rest of the machine.

Later Buchanan had a change of mind and writes:

I was discussing the slant wheel frame with my son. He made a comment that we have no curvilinear frames at right angles to the main frame. They are all visible from the front. He said the when you look at the clock from the side the frame looks out of place. I have considered this and think that he is correct so I want to make a round stainless pillar and two vertical frames as a better proposal. They will be on the same principal as the drop down frame below the fly fans. I also think that they will look lighter and disappear into to a similar background. When you look at the clock from the side we only have straight lines.

His son was absolutely right! I had a similar problem with the frame, but could not put my finger on it. To me it looked clunky and heavy when inserted into position. Fortunately the frame so far was only a plastic mock-up.


These drawings represent the new frame design. The ivy design is now parallel to the main frames with similar designs. These will be joined by stainless steel pillars.


The frame design is rough-cut on a jeweler's saw from the brass stock.


The frames begin their finishing fabrication. The rough frame on the left begins to get further refinement.


Here Buchanan uses a block and super glue to hold the slender frames in place during drilling and milling.


A hand held graver is used for the final touches. Next a comparison of the frames before further refinement, right and after, left. One can see the thinner, refined profile.


The completed frame and next a side by side comparison is seen between the first frame and revised frame design. We have reduced the bulkiness of the frame considerably, especially on the left side where it would mount to the movement frame.


The variable differentials as well as the input drive that is positioned from the rear of the assembly are mounted to the revised frame.

The partially completed output drive assembly on the left is now attached to the frame; a preliminary peek what the sun / moon rise-set module will look like. 


Can you find the frame for this module? Instead of standing out it has disappeared into rest of the mechanism.


This video shows a demonstration of the Janvier style variable differentials governing the moon's rise and set within the sun rise / moonrise - set module.

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