Differences Between Spilhaus Space Clock Models
In owning several of these clocks with a wide serial number range, I have noticed a few changes that were made over the years of their production. Several of these differences, notably with the large space disks, are noted on the prototype and unlighted clock pages. At approximately serial number 1000 or so, the aluminum gears were replaced by nylon gears. Also, the clock hands were changed, the sunrise/sunset oval on the star disk was changed, and a couple of holes in the metal chassis were deleted. The earlier clocks have a white guide for the large disks that inserts at the top, it looks like the white guides in the pictures of the gears below. This guide is not fixed in place. The clocks that have it also have a thin piece of plastic glued to the inside top of the brass arch, presumably to act as a stop for this guide so that the motion of the disks doesn't carry it to the side. Some of my clocks have the plastic stop but no guide. I assume they were removed sometime in the past.
The picture below shows three of my clocks side by side. From the left: prototype, early production (ser. # B690), and late production (ser. # B 2559). The unlighted model is the same as the B690 clock, except the printed text data is in a different location and the electrical connection is horizontal instead of vertical. The adjustment shaft housings are at different angles on the prototype clock and the aluminum back goes all the way to the top. Also, the housings were made out of nylon instead of aluminum on the later production clocks. The clock motor is different on the prototype - the adjustment knob comes out of the left of the motor housing. On the production clocks it is to the upper right of the motor housing and comes out perpendicular to the back of the aluminum back. The plug of the prototype is also in a different location.
The next set of pictures shows the differences between the gears of the prototype and production clocks. The leftmost picture shows the prototype's gears and the right picture shows the gears of a production clock. The gears from the left: The first gearshaft of the prototype has a single large gear whereas the production clock has two small gears. The second, third and fourth gearshafts are basically the same for both clocks, differing only in positioning. A special thanks to Michael Sands of The Sands Mechanical Museum for use of the picture of the production clock gears.
Notice the white plastic guides for the five large space disks used on the prototype and production clock above. The picture below shows a different black round guide that is used, in the same positions as the white guides, on my unlighted model. Note the three curved cut outs on the horizon disk that fit the black guides. This horizon disk is different than the ones on the lighted and prototype models.
The picture below shows the inside of the arched brass top of the unlighted model. There are three brass pieces glued to the inside of the brass top that help to prevent the disks from being dislodged when the clock is handled. The left side is actually two stacked pieces of brass. The top piece is shorter and only goes about 2/3 of the way to the front. The horizon disk rests where the front edge of this piece is. Removing the disks is difficult since the horizon disk catches on this piece of brass, it is a really tight fit.
Updated March 5, 2011