Definitely not a small calculator. In inches, it has a height of 23 inch, is 18-inch-wide and 10-inch deep. For fans of the metric system: a height of 58 cm, 46 cm wide and 25 cm deep. Operates with values up to 1024, and can count and multiply, as multiplying can be seen as repeated counting. (5 x 7 becomes 7+7+7+7+7)
Does not use batteries or a solar panel. Does not use any power source at all, except gravity. The numbers are represented with marbles, as well the input values as the result.
I found an example of this principle on the web and I decided to build one myself. With some modifications, as a mechanical calculator needs the look of a machine. And as it uses no electricity, the machine may have an appearance as it could have been used in the 19th century.
(As one goal of the machine was to make people familiar with binary numbers, there is much attention for setting up the numbers)
The movie above does not give any clues away. The movie below will show you the entire principle:
Building the machine
Most of the building part is easy and can be understood by looking at the pictures. There are only two parts with a little higher range of difficulty: the flipflops and the mechanics to operate the sliders.
At first, the flipflops were entirely made of wood, but reacted a little unpredictable. With sums like 3 + 3, the flipflops need to act very accurate, as the flipflop on line 2 must deal with 3 marbles: one is stored in its memory, one as handed over from line 1, and one comes from the upper slider. To solve the inaccuracy, I added some aluminum strip on top. After this adjustment, all operations became accurate.
The other part with a higher level of difficulty are the sliders and the handles to move them. Inspired by the old-fashioned cash registers, I’d like a handle for operating the machine. As there are two sliders (a top slider to make it easy to place a value, and a result slider to hold the marbles on the sum-line) which work together, I’ve used two handles: a “count-up” handle, which adds the marbles to the central part of the machine (you can call it memory), but also opens the lower slider to let marbles pass which are no longer needed in the memory. As you store two marbles after each other on the row with value “1”, only one marble on the row with value “2” is needed in memory: the other falls down, and as the result slider is open, it won’t stay on the sum-line but falls down to the marble reservoir. The second handle shows the result, by closing the lower slider, and turns all flipflops to their start position. If a flipflip was holding a marble, it will fall down, and remain on the sum-line. There you can read (or count) the result of the sum.
As the upper slider is always closed when no handle is used, it has a spring that automatically close the slider. The lower slider remains in its last position. (Actually always open, except when a result must be shown)
The movement of the handles is transferred by nylon rope and handmade pulleys. Pulleys are not necessary, but an easy way to keep the rope where it belongs. As the accuracy is not 100% (all had been sawn by hand, I have no CNC router), it turned out to be a little problem to turn all flipflops to their original state. To solve that I used some thick copper-wire between the hinging unit and the plug of the flipflops.