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Mechanical adding machine

You might be surprised why I am suddenly talking about adding machines on this website. It is a newly found subject I am eager to explore, and I figured it might be fun to do it together with all of you. I love electronics for the fact that it is easily interconnective. It is really easy to build something complex simply by mashing simple subcircuits together to solve a difficult task. But this method of designing also obscures the true art engineers possessed back in the ol' days: solving difficult tasks with little components and heavy design restraints.


In the modern world we have microprocessors, and our goal is to turn any physical interaction into something digital as efficiently as possible. That way stuff can be tied together quickly with code by a couple programmers, and it simplifies the designing process. As a con, this also makes modern electronics significantly more unreliable. The physical components are smaller, making them having a smaller life expectancy, there's also way more of them, meaning that theres more links in the chain where one can fail. But analog electronics isn't the only way to accomplish a complicated task with fairly little means... there was a time where solving problems mechanically was also a very viable option! Allow me to take you back to the Deutsche Demokratische Republik (East Germany) in the 50's, 60's, and 70's!

Before the time electronics weren't very miniaturized, complicated tasks were almost exclusively done by mechanical systems. Things like vacuum tubes and early transistors were notoriously expensive, and fairly unreliable. You'd often see that large electronic computers of the time spent a fair amount of time not being in operation because a vacuum tube burnt out. For critical applications, they sometimes built two, so they could quickly switch back and forth between the one that worked and the other that had to be repaired. This resulted in a fruitful environment where mechanical calculators could develop into very complicated, but relatively reliable and affordable machines. One of these machines was called the "Ascota 170". Maybe one of the most versatile mechanical computers to be ever commercialized! This machine was sold as a "buchungsmaschine", a bookkeeping machine. These were built for small businesses to... bookkeep! These bookkeeping machines could run small programs to perform a complex mathematical task, and tabellize a result. Multiple programs could be made by request at the manufacturer, and were hot-swappable. These machines are pretty similar to the program "Excel" nowadays, and are fully Turing-complete! And whilst for some reason, on the internet it is pretty popular to hate on engineering east from the iron curtain, I think it has something magical. These engineers really knew how get as much function out of as little parts as possible. This machine is a perfect example... and at a price of a Trabant! When one popped up closeby in Germany, I got a friend of mine excited enough to join into that project of acquiring and restoring an Ascota 170.


During my research, I came across Wim Hasselo. A specialist in mechanical calculators and photographer, with an incredibly well documented collection. He happened to have made efforts tackling these monsters, and I went to ask for advice. With this being my first steps into the world of mechanical calculators, he gave me prescious advice: fathom an Ascota 110-4e, before you tackle the 170. The mechanism behind the keyboard and printing system are similar, the arithmatics unit is exactly the same! So that's exactly what I did intended to do! I ordered an 110, my buddy and I jumped in the car, drove past the Ruhr-area and pick up the 170 using our... rough... German speaking abilities, drove past Wim to see these mechanisms operate in person together with a great explanation (which I'll further discuss down below), and went back home to completely ignore his advice and starting to dismantle the 170 in a destructive wave of excitement:

Ouch!! I like to think of myself to be a clever guy every now and then, but it is usually immediately followed by shooting myself in the foot. Atleast we took pictures of the dissasembling process, but how about we go back to square one, and actually follow up the advice I received... lets make ourselves a little bit more acquainted first with the Ascota 110! 

A quick introduction

Germany absolutely is the number one place to get yourself a mechanical calculator in Europe. People seem to have held onto a TON of them, and there seems to be a lot of German brands in general. They're cheap and easy to find, a lot of sellers seem to use PayPal, and with a little bit of luck they're willing to ship the calculator to you! I tried to find the cheapest Ascota 110-4e to mess around with, and take apart. This resulted in an old listing from late 2019 with the calculator I needed for only 30 euros including shipping to the Netherlands... what a steal! The pictures looked grainy and blurred in such way it appeared the photographer sneezed whilst taking the picture. The machine looked a bit crummy too, so I hoped to receive a beaten up calculator in a poor enough condition where I wouldn't feel guilty for dissasembling it... Boy-o-boy was I wrong! Whilst the calculator was really dusty, and the original cover had a mould problem, the machine behind the dust was in almost brand-new condition! An hour worth of scrubbing and elbow grease shows the following transformation:

The situation gets even worse... IT STILL WORKED PERFECTLY!!! What a waste of money!! I wanted a project, and I got myself a finished product. I'll feel too guilty dissasembling it, and I want to save myself the bad feeling of ruining a beautiful piece of history. I wanted to post a restoration, but that's not gonna happen now. What I will do, however, is to provide an explanation how the device works as a reference for the Ascota 170 restoration. 

Operating principle keyboard

I am not well acquainted with the terminology around mechanical calculators. Therefore I'll be keeping one eye pointed towards Wim's explanation (in the left menu, click "rocking segment" under the "calculating technologies" tab), whilst trying to come up with my own explanation.

Due to the holidays I'm taking a break with most projects. Therefore content won't be added to this page for a while! 17-07-2022

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