Continue planisphere module  - March 2018

In this segment one will see a number of instances where adjustments and some reconfigurations had to be made to fit this module into the existing machine structure.

This month  Buchanan develops the drives for the planisphere. The planisphere has two input drives, sidereal time to the star disk and mean solar time for the sun. The sidereal drive derives from the demo drive on the left with the solar input from the right coming from the tellurian. In reality both sides are turning at mean solar time, the gear set placed just below the center demo select push selector for the two speed transmission is what derives the sidereal input. Buchanan had studied the wheel and tooth sizes of these four wheels carefully to develop a symmetrical look to where the drives come evenly from the left and right sides and dip down towards the center to just above and partially behind the planisphere dial work. It comes out to almost a perfect sideways figure ‘8’ or like the sign for infinity - ∞.

As we were discussing this assembly Buchanan realized that the planisphere wheels were tucked behind those that comprised the demo drive input from the tellurian. Originally these were to be part of the planisphere module; mounted to the main pillar upon which that module is mounted. However, that is not possible as they are behind the input wheels. This turns out to be a bonus since the wheels will now be mounted via dumb arbors to the center pillar of the main clock frame and remain there. This allows the planisphere pillar to be trimmed away to where it will disappear behind the dial work, whereas before it had to rise above the upper rim to catch the arbors to which the wheels would be mounted. This will allow the wheels to float above the planisphere dial.

Buchanan writes: To establish the final positions for both input gears I had to properly screw on the thermometer bracket.  This meant that I had to dismantle the clock to the point shown here, (first photo). This now takes a little while, about half an hour. Then I had to dismantle the thermometer bracket to be able to drill the two screw holes. Then reassemble and glue in position on the clock, I had to make an extended drill and tap, (second photo) When the glue had set I drilled the holes in the main frame (third photo), then removed the bracket from the clock, removed all the glue, dismantled the gears on the bracket to drill the holes clearance for the screws. Make two special screws. Tap the holes in the clock and clean off all the swarf. Then on the international time bracket (this had screws already) I had to thin down three gears, (fourth and fifth photos) this meant that I had to dismantle each gear to be able to machine it. The steel pinion required the removal of the thermometer bracket again. Then I fitted the planisphere disc to the demo drive wheel. This needed a spigot and a spacer and the shaft had to be shortened as well. Then I cut the spokes. Then everything had to be reassembled. I also have the artwork for the thermometer corrected ready for the printer and chased up the glass dial printing which is ready for collection the other side of Sydney. I also prepared the blanks for the last two gears to take home to cut the teeth on this evening.

So while it looks like I fitted one small gear today there was a little more happening.

Buchanan writes: I had to fit the lower sidereal gears behind the planisphere pillar before I could go any further. Photos are showing measuring the distance between pivots, first photo and the two sidereal drive gears mounted, second photo, and the gears that are mounted fitted in the clock with the front Solar idler gear balanced in place. You can see the Sidereal gear behind the Planisphere clamp arms in this photo (photo three). Third and fourth photos, show how much of the gearing will be exposed, and then the four gears in the fifth photo. The only frame visible will be the single bearing for the solid gear above the planisphere dial, third and fourth photos.

I can mount the four sidereal gears on the main clock, fifth photo. This is like juggling in real slow stop motion. Nothing happens fast but we have 400 hundred balls (gears).

The wheel set directly above the large planisphere wheel is now spoked out.

Deryck writes: I have the next gear set almost fitted. As you can see in the second photo, the gear has a temporary brass arbour with a big flat head. I have glued this in place so that I can make sure the gears are meshing properly. I will remove the frame and set it up in the jig borer with the brass arbour central to the spindle, then knock off the brass arbour and machine the frame to take the bearings. Next after this is the wheels for the sidereal drive and then the rotating gear assembly on the planisphere disc.

Buchanan writes: I have the main wheel complete for the sidereal drive. I had to swap 2 more gears around for easy removal purposes and this required that the main wheel had to be set back against the frame so we have another interesting wheel. I have the next gear set complete; tomorrow I start in hanging 4 more gears in mid heaven. It is a bit of a problem to work out how to arrive at the centres as there is not much to measure from.

The first three photos show how this setback was accomplished using six spoked offset collet.

Buchanan writes: I have the next two gear sets nearly complete. I am trying to figure a way to hang them on air as there is not much else to hang them on.

This photo shows one pair the gears from the gear set positioned where it needs to be using a long stick. One can see that there is nothing nearby to support these wheels.

Buchanan writes: This is the process for mounting the last two gear sets.  

First I glued on an oversize brass plate onto the main clock frame. This will become two small brackets finally. Then I made two flat discs with an attached arbour. These were placed in the gear set and glued in place with Loctite, first three photos . This gives a little more time than superglue. It will not set while you are moving the part but as soon as it remains stationary for about 3 seconds it grabs. Now I can remove the back plate and drill it for mounting screws and dumb arbores. Then I can remount and check before I finally cut out the back plate into two individual cocks. This will take most of the rest of today. Then on to fitting the dial plate. I aim to have all the gearing done by Wednesday.

The last photo shows the gear pair within the context of the planisphere wheel work.

These four photos show how Buchanan made the two wheel pairs float on air. The wheels are supported on a pair of dumb arbors set into a set of custom brackets. These are then counter-sunk and aesthetically blended into frame. This is reminiscent of the small brackets that were made to hold the power reserve arbors within the main frame back in March of 2010. This sort of retrofit work, offering a clever, yet elegant solution is very labor-intensive.

The first photo shows three more wheels to be made that will rotate with large brass disk to which the enamel planisphere dial will be secured. Next a drawing of the planisphere frame showing how the current rectangular brass piece will be machined into its final curvy ivy vine design in keeping with the rest of the machine’s frames.

The planisphere main frame is machined in the first three photos. The fourth shows the bracket and pair of locking arms.

These two photos show the locking arms in the open and locked positions. These secure the planisphere module to the movement.

This photo shows the planisphere wheel work mounted to the main frame. It looks like the movement for a an elegant great wheel skeleton clock.

Another view of the planisphere works mounted to the movement.

Now Buchanan begins to fabricate the lower base support for the planisphere main frame. On this a second curved piece will cradle the dial. The first photo shows the cutter engaging the brass stock to create the decorative edge. The second photo shows the cutter profile next to the resulting profile on the brass base. The next two photos show the subsidiary base positioned next to the main movement base.

Buchanan writes: I have spent today recessing the Fasoldt Screw heads and adjusting the whips to miss everything. So I now have the strike working with the planisphere in place.   

I am adjusting front to back positions of various gears on the planisphere before I go further. And there are the two clutches for the sun hand and disc to squeeze in somewhere as well.

Here we see the many adjustments needed to fit parts that are added to the machine after prior mechanisms have been made. While Buchanan is a wizard at anticipating these types of mechanical conflicts, the complexity and sheer number of parts invite these problems. The Fasoldt frame screws were originally made as all the other screws, to be a modified cheese head to stand fairly proud from the frame. The large planisphere wheel made these impossible, thus the change to a recessed position. The same was true with the Fasoldt detent whips. These sweep a fairly large area and have been a source of conflict in the past with the two adjacent winding squares. Notice the small clearance between the whip and planisphere wheel in the third photo.

Buchanan writes: I spent today reassembling the clock. I did housekeeping as I went along. Adjusting end shake, correct spacing front to back of wheels, make and pin collars on the end of dumb arbors, first photo, adjust the fit of the thermometer, (you can see how a wheel runs half inside it) note more details to attend to on the next disassemble, and more little details. Everything is working now with the planisphere installed. So I can now carry on working on it on the bench. This fitting of the planisphere was far more involved than I first expected.

The front of the clock is now complete as far as gears are concerned. So I took a few photos of it with no dials on. Unfortunately it won’t look much more complicated from the front. Only the orrery on top.

 I’m sure Buchanan is glad there are no more wheels on the front!

Buchanan writes: These photos show the bearing housings for the sun hand drive. The first and second photos are of the process known as pointing, where the centre of the gear is marked out on the plate in the jig borer.  I am paying the price of not watching front to back use of space on the Fasoldts. The dial looks like it will be pushed forward a few millimetres. There is a limit to how much I can compress this disk wheel work, but I am doing my best.  It should start to look like something soon.

These four photos show how the three rear wheels on the dial disk will be secured. They will revolve with the entire disk and will drive the sun hand though the hole visible in the disk.

Buchanan writes: I have the sun hand wheel and arbor fitted complete. First photo, is pressing the sun hand arbor into the collet. Second photo, is the planisphere disc fitted on its arbor with its setting clutch. All I have to do on the gearing is the fit the double gear, third photo, onto its arbor and add a clutch between the double wheel for the sun hand. That will complete the gearing for the planisphere. There is the sun hand to make.

Buchanan writes: I have the last gear set with clutch complete. I have a little adjustment to do and then I will complete the pedestal and onto the setting ring and sun hand. 

I don’t normally include comments by the general public, but this statement sent to me this month was so eloquent in its description and purpose behind this project that I thought It should be shared:

I'm newly arrived to your project, and indeed new to interest in horology. But what a gorgeous piece! It's an physical embodiment of the ideas we have of thinking of time, and in fact also in some ways a museum of horological ingenuity, as for example in how it incorporates several types of remontoire(s). It's wonderful to see you so generously sharing your love of mechanical beauty, ingenuity, and time in the form of an entrancing legacy. Thank-you! Time stops as we watch it go by in the motions of this clock, while we are mesmerized by this artistry and vision.