Marble Machine

Gerhard Enste, a member of CompuRama, has been able to build this machine. On 14 February 2009, he demonstrated his maschine to the members by solving the chain calculation 5 + 2 + 1 + 2 = 10.

In spring 2013, as part of the course "Rechnen in Holz" (calculate using wood) six children from the third and fourth grade of Ratoldus-Schule and Tegginger Schule extended the machine. They build wooden boards to convert positive and negative numbers from the decimal to the binary number system.

Martin Völker, member of CompuRama and head of the former course, produced a German documentary film, in spring 2015 :

The computing marble machine of the CompuRama (12:25 Min.)

The carpentry of the "Pestalozzi Kinderdorf Wahlwies" supported the construction of the machine. Therefore, CompuRama is highly grateful!

Plans for the Convert Boards
Adobe Acrobat Dokument 60.6 KB

This plans were used for the construction of the convert boards. We printed the plans on DIN A4 paper, cut them out and fixed them using tape to the boards. The red circles on the left and right side mark the holes for the pins. Those pins fix the position of the transport-"register" below the chosen number. The blue circles mark the holes for the chosen number. The person that reconstructs the boards, has to adjust:
- the width of the boards
- the height of the rows
- the position and size of the blue holes
to his marble machine.
We drilled the holes into the boards and positioned the honed pins. Afterwards we drilled the holes, for the positioning pins, into the transport "register". Then we put the register under each number and marked the number holes on the register. In the middle of the so obtained marks, we drilled the blind holes into the register by adding 2 mm. Thus, we compensated the inaccuracies of the drilling of the number holes. Finally, we characterized the left side of the register and the boards with red and the right with a green colour, so that the register and the board are placed together in the correct direction.

The basic idea and model of the marble machine have been used from:

A German video documentation of a similar machine is available:
(2:34 Min)

During the following video (2008), from minute 4:57 to 7:14, a simulation of a marble machine is demonstrated:
(slightly distorted sound)

A pretty weird, german science fiction story (about five densely written DIN A4 pages) in which also something like a marble machine appears, can be found at:
This page also contains some more www addresses of marble machine.

As a comparison to an electric abacus and in general, to mechanical calculations with binary numbers here, finally, the reference to a simulation of the Z3-adder is available:
(Please choose "Simulation des Z3-Addierers starten" on top of the page.)

On the occasion of the premier of the new documentary film regarding our marble machine, an article in the local newspaper "Südkurier" was released on 6 October 2015:
"Schüler bauen Rechenmaschine aus Holz".

brown table with devices

This photo was taken at the booth of CompuRama during the "Kulturnacht Radolfzell 2015". It shows the current expansion of the marble machine including new bars and the measuring tape, to convert the binary result back to a decimal number. The short bar for the "1" sliped under a board in the picture.