View Full Version : Mechanical mechanism porn

11-11-2014, 10:08 AM
The workings of the Millionaire 'direct multiplying' calculator;


We have three of these machines at work, although only one is currently operational.

Paul Alciatore
11-11-2014, 04:16 PM
Boy, talk about a home shop project.

When I was in college in the 60s, the department had an electric, mechanical calculator that did addition, subtraction, multiplication, and division. It was fun to watch it chug through the multiplication and division by successive additions and subtractions. I bought my first electronic calculator, a four banger, a year or two after seeing it but no chug-chug.

11-11-2014, 06:35 PM
I once had a Friden mechanical calculator, which jammed and broke, so I gave it to the kids to take apart (long ago when such things were worthless). INcredibly complex and mysterious.

Now for grins, though, I have one of these:


The original design, by Odhner, was Russian. One of the few things those old Soviets could accurately say they invented first!

By the way, if you've ever watched the Billy Wilder movie The Apartment, you may recall that the hero works in an insurance office populated by rows and rows of those old Friden or Monroe calcs, and makes an amusing rhythm with it. It was possible to make some very complicated rhythms with a big Friden in multiplication mode, by multiplying one recurrent sequence by another - say 35353535 x 18181818. Loads of fun. It also had a "Div Stop" button, because it approached certain problems by approximation and simply threw away the remainders. As a result, it was possible to get utterly stalled on a division like 4/2, if you took it to eight significant figures. It would simply never stop.

The Brunswiga has a very complicated method of division, in which one rotates the crank back and forth, and when it's done, it rings a bell.

11-11-2014, 09:05 PM
Anyone have a Curta? Looked like a pepper grinder. I always wondered how they worked.

Lew Hartswick
11-11-2014, 10:37 PM
Anyone have a Curta? Looked like a pepper grinder. I always wondered how they worked.
In my sports car rally days I'd have given a lot to have one. But the money just wasn't there. :-(

11-12-2014, 10:18 AM
Anyone have a Curta? Looked like a pepper grinder. I always wondered how they worked.

Naturally, there is a web page devoted to the Curta - it may answer some of your questions:


Alistair Hosie
11-12-2014, 01:39 PM
It must take a special type of mind, or perhaps just years of engineering experience to design, and make ,then fine tune,something as complicated as this.I also was fascinated many years ago when Bronwen and I were not long married about six years . I bought her a knitting machine,This device was then state of the art and had a punch card mechanism to make your own designs .I just was fascinated by this machine as well as ( since then )weaving looms (industrial).Take care and thanks for the thread.Alistair