Ray Mackay


There are Web sites throughout the world containing pictures of mechanical calculating machines. Not many such sites have details of the internal workings of such machines, although collectors and hobbyists like to endeavour to restore them. Without specific information this task can be risky and damage to the machine may result. The enclosed pictures and drawings cover the the MADAS 20BTZG and are provided to assist such hobbyists and enthusiasts. The information should be used in conjunction with information at

The author wishes to thank Geoff Bowles for his assistance is allowing the taking of the pictures during the release of a jammed multiplication mechanism. The 20BTZG supplied by Geoff also indicates that many of these machines may be suffering from jellified oil which may need thinning out with kerosene and the mechanism re-oiling with light sewing machine oil.

The images are actually hyperlinks and clicking on them will take those interested that have the patience to the or original size (scan size) image.

A CD of images is available. It contains around 650 Meg of files, information, memorabilia etc and has now been upgraded to include the above MADAS images and the MADAS web site.  The CD also, now, includes PDF files of the exploded drawing of the inside of the MADAS 20BTZG.   This is, as you may realise, a non-profit venture simply designed to place the information in the hands of mechanical, and electronic, calculator enthusiasts. The idea is to release the information so that it doesn't get lost to future enthusiast.s

The following is a price list for people wishing to get the CD and able to send $AUD:

America $2-00 for the Blank and $3-50 Post and packing
France $2-00 for the Blank and $5-00 Post and packing
Switzerland $2-00 for the Blank and $6-50 Post and packing
Russia $2-00 for the Blank and $6.50 Post and packing
Germany $2-00 for the Blank and $6.50 Post and packing
Chile $2-00 for the Blank and $6.50 Post and packing
China $2-00 for the Blank and $4-00 Post and packing

Other zones are possibly similarly priced to one of the above located near your zone.  There seems little rational behind pricing as America is just as far from Australia as any of the others.  I guess planes go there more frequently as thus bulk handling is cheaper.

Ray Mackay

P.O.Box 1270
Doncaster East
Victoria    3109

Above view Above view - 2
Above - Keypad Above - Left view
Above - Right view Below - View 1
Below - View 2 Below - Keypad
Carriage Detail Carriage Detail - 2
Left View


From: Nicholas Bodley
Subject: Photos of MADAS
Date: Feb 14, 1999

Delightful photos!

What with the relatively-primitive setup I'm using, I had to wait until I logged off to see the images (long story; mostly irrelevant). Thanks, so much! About all I missed seeing was the control mechanism (which you might call "above right" in your naming scheme). Also curious about that group of dials closest to the operator, but there might be little of interest. (What are they for? An extra storage register?) I hope, someday, to see these same images with superimposed callouts. (Use narrow black strokes on top of wider white strokes...)

Adobe Acrobat Reader is a real slug (really slow) on my current machine; I'll be fixing up the fast 486 sometime soon. That means I didn't see the .PDF image, yet.

I realize with new vividness how little one can sometimes figure out about an unfamiliar machine when unable to turn a handcrank (or knob?), or simply to reach for a part and try to move it.

Sorry to delay replying; have a really-nasty case of pulled muscles in my right hip (artificial "mushroom" in place of the natural ball) and lower back, and was off line for a spell.

The images were so good (viewed with the zgv program running under Linux) (I'm still using Conex (really-good, geek freeware) for a dialup shell acct.)... so good that I could sometimes see typical, almost-gorgeous European manufacturing practice for precision mechanisms. Reminds me of American desktop machines (haven't seen a Marchant, yet), in which everything is only as "pretty" as it needs to be. The Europeans have a way of making things gorgeous! Makes me want to own one. (I'll bet the innards of Diehls are just as gorgeous, too.)

I'm still puzzled by the Leibniz drums/stepped drums in the MADAS. The simple-minded scheme would look like this, "unrolled", or as an M. E. would say, "developed", where each "X" is a gear tooth.


However, the stepped drums in the MADAS don't seem to look like this, and my guess is that it uses a scheme similar to Monroe and Friden, in which the 1..4 (or, maybe 1..5) tooth group is "re-used" for 6..9, by enabling a 5-tooth segment to add its count, so that the keyboard selects on a more-or-less biquinary scheme. In other words, for instance, pressing a 7 key, instead of moving its selector slide 7 positions, and selecting a single 7-tooth level of the stepped drum, actually would select a 5-tooth level as well as a 2-tooth level. True? (I actually can ask a one-word question!)

This scheme is used, I'm just about positive, to prevent the higher-numbered keys from being harder to push.

With best regards to all,

Nicholas Bodley


From: Geoff Bowles
Subject: Photos of MADAS
Date: Feb 15, 1999

Just a note to thank Ray publicly for all his help in fixing my MADAS and for persevering in his efforts to get some of his vast knowledge to stick in my tiny brain for more than 5 minutes! He has been tireless in providing advice and encouragement and I would have given up a long time ago leaving just a pile of nuts and bolts without him.

I am getting more comfortable in pulling apart and re-assembling the more basic parts of my machine and in identifying just how particular bits of it work - my hat is well and truly off to the people who designed these machines and to Ray, who learnt to fix them without any manuals at all!

Re the above quote, whilst not wanting to get too cocky - since I haven't actually got it entirely reassembled and working just yet (touch wood) - I would be happy to take any other photos of the internals that people would like to see. The same applies to my 1921 MADAS (the long brass one that came between the Millionaire and the above machine), although I won't be touching it at all until this one is completely back together - it's hard enough to keep track of where the bits of one machine go at a time!



X-Number World