How to open a Madas

Below, here’s a video showing how to properly open a Madas.

This demonstration, for beginners, indicates the different steps that should be followed.

It is important to carry them out in the order, taking care to not drop a small screw inside the machine.
Work slowly, carefully, using an appropriate screwdriver. It is perhaps necessary to grind the tip of the screwdriver so that the latter perfectly adapts to the width of the screw slot. Use also a precision screwdriver to remove the keys on the keyboard.

Observe that all screws have not the same format. In particular, the two special flat-headed screws (one on each side panel) which have bushings behind to support parts of the mechanism. The screws are special, and the bushings can get lost when the panels are removed if one doesn’t know that they are there.


When the machine is open, you can begin to clean and lubricate movable parts which are stuck. At the end of the video, you can see an example. These specific parts are generally very strongly glued by old dried grease. Most of the time, it is not necessary to remove other parts of the machine. However, it is often tedious to find the places where are deadlocks. It is a job that requires experience. Concerning the method of cleaning and lubrication, there is no perfect and definitive solution.

The subject has been treated comprehensively by John Wolff.
This information is available on the site “John Wolff’s Web Museum” (Notes on Overhauling a Mechanical Calculator)