Back Up Next

Complete planisphere module  - May 2018

In this segment the planisphere module is completed.

 

Buchanan writes: Yesterday I machined the second part of the base. I am waiting for artwork for the setting dial and brass for the main bezel. I will be fitting the two base parts together and starting to machine the setting dial today.

 

The ring depicted here will also become the setting dial for the planisphere. The double nomenclature for the months is necessitated by the narrow window through which the months will be read.

 

Here we see the 468 teeth being cut for the setting dial. See video below,

 

Buchanan writes: The setting ring is complete now, the engraving was full of burrs so I had to go over it by hand. I can fit the enamel now and make the sun hand. Then the bezel in the rough with the setting window. I will fit a temporary paper dial until the end. The ring is 61/4 inches in diameter.

 

The black fill for the engraving is a tough automotive two-pack black epoxy rather than the traditional black wax which is far less durable.

 

A decorative brass nut is shown here to secure the planisphere enamel disc. All of the calligraphy was copied by the enamellers in 2012 from the original artwork produced by Buchanan in 2011. Now six years later the star disk is united into the machine. This is the last example of a part made several years earlier that comes into the fabrication of the clock at a later in time.

 

The first photo shows the hand turning of the setting ring edge to create a bezel as seen in the second photo.

 

Buchanan writes: I had to make a spacer ring to go behind the enamel to move it forward to clear the arbor ends. I will fix the setting  ring to the main brass disc with screws into the edge of the main brass disc. So we will have 12 little blue screws between the month names opposite the first of each month. This is another nice touch that Buchanan adds time and again to this project.

 

 

 

Buchanan writes: I have spent this morning tidying up the sun. The second photo shows the sun face through the microscope and reveals the rough cross-hash surface produced by the mill. The fifth photo shows the same part after hand finishing to reveal a smooth surface.

Buchanan writes: The last photo is of the layout of degree markings for the planisphere aperture. We may need to use less concentric rings but the radial curved lines look cool. They also give us star information, which we don’t have anywhere else so we may be able to string out an extra complication or two, if we label the lines correctly. One is the declination, I think, and the other is the hour angle. I cant think of any more. The sun does move around the ecliptic, so if we could mark is path you would have the position of the ecliptic in the sky.

 

 

The first two photos show the sun’s eyes are being made. In the first photo the two blued screws. The end of each screw in rounded and polished and then blued. The eyes of the sun are then drilled and tapped and each screw is just the right length to be fully screwed in to be flush with the face of the sun, next photo. The fourth photo shows a happy and wizened face.

 

 

These illustrations show Buchanan's choices for the Latin inscription on the planisphere mask. The fourth photo is an idea for the guilloche design on the remaining portion. Buchanan writes: Here are a few kick off proposals. The engine turned background will be on each one but the print will be in a polished smooth area with a frame. Somewhat like the brass test piece. Photo 510, third example, is my preference.  Both of us agreed on this.

If you have a type of engine turning that you would like me to try to replicate let me have a picture. I do think some kind of radial pattern would look appropriate to a linear or square pattern.

 

The first photo is a sample engine turning Buchanan had done for the center of the Sun/Moon rise dial and is shown on the fourth illustration above. I had submitted the example in the second photo, showing the back of a pocket watch, which was my choice for the planisphere mask background.

 

This is the initial mockup of the planisphere mask. Does this look a bit like a stone material? It's made from the kitchen countertop product, Corian. A curious choice of material, but Buchanan says it machines well and is suited for the purpose.

 

 

The grid is now cut out and the Corian is spray-painted. The result was very good. Buchanan writes: Some more countertop and a few comments.

This is only countertop material. Brass will look much, much crisper. Finer and shallower engine turning needed. Inscription plaque will need to be adapted to the lettering. The spiders web will be less than half as deep much thinner and no radii at the intersections.

Also perhaps a couple of silvered plaques to describe the lines: a N,W, S and E for the direction and a few of degrees for the height. That makes two complications for the stars positions. A brass ring for the ecliptic (if I can think of a method to  attach it to the enamel) would bring it to 3. As well as the position of the sun in the sky, 4. This is brilliant and shows how Buchanan is always looking out to improve the impressive nature of the project through an ever greater complication count.

 

 

Today Buchanan finished the Corian mockup of the planisphere mask. On all the other dial work we have a conventional enamel dial ring surrounded by a metal bezel ring on the inner and outer edges. The planisphere has a solid dial disk and is mounted behind a metal structure that reveals only 40% of the disk surface through an oval aperture. This structure is the mask.

The guilloche design on the mask surface came out beautifully. Buchanan suggested a few changes to make it a bit more refined. I think this will work well with whatever bezel design we decide on for the other dials. At this point I am still looking for a rope-style rim. The knurled rope design will be not be as shiny as the smooth contoured surfaces as depicted in the mockup bezels and will offer a softening effect. He also suggested that the since a rope design has a handed direction, that we make the rope mirrored for the dials on the right and left sectors – brilliant!

The positioning of the disk, being recessed behind the edges of the mask’s oval opening gives a shading effect that makes the edges slightly darker than those toward the center of the opening, and is what Buchanan was depicting in the original artwork. That subtle shading did not make it into the actual enamel work, but the effect works. The effect is evident in the third photo.

 

The planisphere is now shown with the Latin inscription “Os homini sublime dedit coelumque tueri Jussit et erectus ad sidera tollere vultus Which translated means “To man god gave an upwards gaze, bidding him behold the sky, raise his erect countenance towards the stars.” This was chosen because the clock’s theme is astronomical and elegantly shows God's creation. It depicts astronomical data from three magnitudes. At the local level the planisphere shows the stars as man would see it from Earth, hence the inscription. The next level is the tellurian showing Earth’s immediate neighborhood with the moon, and inner planets of Mercury and Venus around the sun. And finally, at the third level is the orrery (the last component to be made and shown still in mockup form as seen below) depicting the solar system out to Saturn. The orrery is based on the 17th century design by Mathias Hahn, and at that time the planets past Saturn had yet to be discovered.

This video shows an example of where the sun would be in the sky during the summer solstice at latitude 42 degrees North, Chicago Illinois, USA. One can see the sun emerges from the horizon mask on the left and disappears below on the right far below where the arm holding the sun is below a horizontal position resulting is the longest day that the sun is above the horizon. The opposite will be true at the winter solstice where the sun will intersect the mask when the arm is above a horizontal position.

The astronomical machine fully dressed up with orrery mock up. Everything else is real.

The clock where we stand today.

Back Up Next