Saturday, 9 January 2010

Divisumma 24

It's arrived! My circa 1960 Olivetti Divisumma 24 electromechanical calculator has arrived from Italy. It's in good condition although so far I haven't got it fully working.
First a little background. When I was about 17 (a long time ago!) I worked one summer at an advertising agency doing analysis of some surveys. For this I was equipped with a Divisumma 24. This was, for its time, an amazing machine. It could not only add and subtract, but also multiply and divide, for numbers up to 12 digits. It was very compact, unlike most such machines, and also a very nice piece of industrial design. It fascinated me, and I was especially intrigued as to how it worked. I wrote to Olivetti, and they kindly sent me a green booklet describing in complete detail how one of the simpler machines - just an adding/subtracting machine - worked. A while later I wrote to them again, thanking them profusely and practically begging them for information about the Divisumma. Obviously my letter went to someone else, because this time I got a reply more-or-less accusing me of stealing the book and asserting that Olivetti would never, ever, under any circumstances, give such information. So that was that.
I still have that little green book, and a few weeks ago I took it out of the bookcase and re-read it. I was as intrigued as ever about how the Divisumma worked. A lot has changed in 40 or so years - Olivetti no longer really exists, for one thing, and nobody has used mechanical calculators for three decades. So with Google's help I discovered this source for Olivetti manuals, and a great many others too. A few days later a parcel showed up with seven volumes of green-covered manuals, and I started reading. It's not that hard to understand how it works, but what is truly mind-boggling is that someone was able to design it. Even allowing that it was a process of evolution from simper machines, it is still extremely impressive. Unlike software, which has some structure to it, these are three-dimensional puzzles, where two completely unrelated functions that just happen to need to do something at the same time, can share the machinery. (For example, the mechanism that arranges double line-spacing for totals just happens to be in the right place to reset a lever that controls the way the registers engage for memory operations).
Of course reading these manuals just whetted my appetite again. A bit of searching showed someone in Italy who had one to sell. I paid about $150 for it, but of course the postage - even surface mail - nearly doubled that. And this week it arrived. The seller had done a super job of packaging, including a wooden framework to protect the machine inside the box. It was complete, apart from one minor knob on the keyboard, and the power cord. It even had a roll of yellowing paper.
I rigged up a power cord for it (don't tell the safety nannies about this) and plugged it in. Unfortunately, it didn't work - one of the keys was jammed, and the motor just ran without anything happening. Not really a surprise, but a bit of a disappointment. So then it was off with cover. That comes off surprisingly easy, no screws, just a couple of toggles.
The insides of the machine are in remarkably good condition. There was some fluff around the keyboard, but no rust or damage. All the metal parts seem to be cadmium plated, which means they look the same as the day they were assembled.

I need to say something about the manual, too. The Olivetti technical manuals are also works of art. Every tiny aspect of the machine's operation is described in great detail, with beautiful engineering drawings for every page showing the various levers, bridges, pins, racks, springs and so on - just those relevant to the current description. Once you've digested that, they also include complete instructions for assembling a machine from scratch. The numbering of the parts is consistent through the seven volumes, so once you read in chapter VIII (as befits an Italian product, much use is made or Roman numerals) that lever 73 is key to some particular function, whenever you see lever 73 later on, you know exactly what it does.

So with the help of the manual, I was able to figure out what was jammed, and unjam it. And the machine worked! Well, briefly. For about fifteen glorious minutes it would add, subtract, multiply, divide, and move numbers to and from the "memory" . Even the 30-year old ribbon worked, well enough to read anyway.
But then disaster struck. I started a divide, but instead of the usual kerchunk-kerchunk of the running machine there was just a faint hum, the horrifying noise of the stalled motor. I unplugged it and tried a few things, and eventually it unjammed. Phew! But then I realised things weren't working right, and when I looked, I realised that disaster had struck. Right in the very heart of the machine, a frame had got twisted so badly that it had let a metal rod fall out. This was a totally inaccessible place, without completely dismantling the machine. I was mortified. Just when things had been going so well (I had never really expected the machine to be working), and now, just so much scrap metal. I could almost have wept.
I studied the manuals again, and very carefully, removed the paper roller and associated bits and pieces, saving all the parts in little plastic bags. There was only one problem - a circlip which in the time-honored tradition flew across the room. Luckily I found it easily. That gave me access to the mechanism, from above. Then the real fun started. I found that I could just get a pair of tweezers between the individual elements of the register, and that way I could hold the rod in more or less the right place to insert it. But actually getting it into the holes at either side of the frame was another story. Let's just say it took a long time. Finally the trick was to hold everything in place with wire (actually green garden wire, which gave a certain rusticity to the whole operation). After several hours I had it back in place.
Very carefully I turned the machine over by hand. It seemed to work correctly. But then I discovered how delicate these machines really are. Just like an exceptionally old wine, which is wonderful when opened but undrinkable within ten minutes, so it seems that my early success with the Divisumma was not to last. Every operation revealed some new misalignment or jam, and when that was fixed, another one showed up.
There is really a lost trade and craft here. Back in the day when these machines were commonplace, every town had numerous little back-street workshops, where bent-backed mechanics in brown coats would pore over them when they jammed or refused to work. I'm sure it was a common occurrence. In the few weeks I was using the Divisumma all those years back, it jammed once and had to go for repairs. Probably every machine was in the shop every few weeks. "Oh yes," the brown-coated old guy would say, "looks like the returbitating cam has shifted again, just move it a bit and tighten up the unflurging spring while I'm at it..." and the machine would be as good as new... for a few more weeks.
Anyway, my Divisumma definitely needs some more tender loving care before it will be dividing again. It's a wonderful piece of engineering, and I'm very lucky to have it. It's certainly something to fill those long winter evenings!

8 comments:

hypGnosis said...

Just curious, but did you ever get your D-24 back into operating condition? I serviced these machines up until the time they were replaced by electronic calculators. If I can be of any assistance... please let me know.

Anonymous said...

Well, I was not one of those bent back repair men, but at about 12 years old my father taught me everything there was to know about the Olivetti Divisumma 24, 26 and a multitude of other Olivetti machines. He had been an office machine mechanic even before Olivetti merged with the Underwood typewriter company. As time progressed I began to help my father at work and in high school during the 70's I was earning $10.00/hour while my friends were making $2.50 to $3.50. This paid for my college after which I ended up working for Olivetti until they down sized in the 80's. I have fond memories of those green covered technical manuals which I studied from cover to cover.
The Divisumma 24 was the best of the Divisumma series and was quite reliable when properly timed and adjusted. I once got paid about $400 to reassemble a D-24 that a gentleman's son had completely disassembled. That was a lot of money in those days. The most common problem with the D-24 as with most mechanicals of the day was lubrication. Particularly the racks, sliders and the add wheels. They needed to be periodically rinsed with a solvent and re-lubricated with a very light pure machine oil. The add wheels in particular would get clogged with the ink from the ribbons.
I hope you get it working. It was quite a mechanical marvel and very interesting to watch it work. Now at 57 years old, I wish I had saved a few of the antiques I used to work on. Have fun.

Bob Davenport

Anonymous said...

I used to work for a business machines company in the early 80's in the suburbs of Detroit. Electric Comptometers were the rage, but the Olivetti D24 always captured my imagination. I always wanted one, but they only had broken ones in the office and it never occured to me to get a broken one and fix it. I just figured I would always find one in working order, but I never did. A relative had a school then too and I have to say everything Olivetti made was functional, long lasting and a work of art as well. My favorite was the Praxis 48 typewriter. It was light as a feather and yet did beautiful work. It had features no other typewriter did for 10 times the price. If you hit two keys at once, rather than jam up the typebars, it would stop them from moving towards the page and freeze the keyboard. You had to backspace to unlock it. But hey, it saved a ruined piece of work or having your page covered with that nasty correction fluid!

Anonymous said...

Great tp see someone still is interested in the Olivetti D24.
I used to repair them in the 60 and 70'ds. What a fantastic machine. I just finished repairing my Olivetti M24 and Divisumma 24. Its is really nice to see them running again. If you need help in getting yours to work please feel free to contact me nschmid420@charter.net
I still have some parts for these machines.

Tex 36 said...

The D-24 was a great machine, and a marvel of design. I worked on them, and progressed up to the Olivetti Audit accounting machines. These machines, to which were later added a punch-tape facility were absolutely brilliant book-keeping machines. I am in awe of the designers who developed these machine. Perhaps the only thing which let them down was the quality of the steel from which the components were made. I also worked on Addo-X accounting machine where the opposite situation existed. The steel was brilliant with the Addo's (As you would expect from Sweden), but the design was light years behind the Olivetti.I also worked on Friden calculators, including the square-root machine, which was a nightmare.Great,great days.

jimmiemach said...

Wow! You don't know how much I enjoyed your comments and those that followed. I sold those machines up until they were upgraded to the D 26 and so on. I sold a ton of the Divies from the time I started with Underwood in 1960 until the famous downsizing of Olivetti in the early 80's. They were very reliable.I also like the comment from one fellow on the Praxis 48. I sold them by the dozens. I can still remember going into our Cincinnati office from the back entrance and seeing Bill Rizzo working on them and the accounting machines. His work bench was the first one as you came in the door. I think Bill was a brilliant craftsman. When our dealers gave up on the D24 they would send it in and Bill would quickly get it repaired. Thanks for the memories.

George Krausse said...

Before I came to the US in 1956 I worked 2 years for Olivetti (Branch office) in Hamburg.In 1954 ? when the Divisumma came out they would send older Mechanics to Ivrea for training.The machine was obviously to complicated for All-around Mechanics to handle.Arriving in San Francisco (June 56) the time Olivetti try to establish itself on the west coast + Alaska and Hawaii I met by accident the the General Manager on Vacation on sunday and started working in the City on Monday! They send me , the german mechanic , with a shipment of machines allover .
Fun Time for a 22 year-old Boy

Sandy Johnson said...

I was an Olivetti Canada technician from 1969 until 1979 after which I worked for an Olivetti dealer. Eventually the typewriter and calculator business gave way to computers, of course and we technicians gradually changed what we worked on with the changing products in changing times. I ended my working days servicing photocopier/fax/printer/scanner units which are networked with computers - quite a change from the mechanical cash registers, typewriters and adding machines I started out with.
A couple of the most frequent problems with the D24, the M24 and the T24 were breaking symbol racks and worn out fiber gears - the one on the camshaft which is driven by the worm on the motor shaft. I still have the fiber gear splitter we user to remove that gear, which we replaced by a split gear into which a couple of metal
pins were inserted to hold it together. Silver soldering the symbol rack was done very carefully with a propane torch after packing asbestos around it to keep the other parts from being overheated. I have several D24s and an M24 and a T24 as well as many other Olivetti, Underwood, IBM and other machines.
Sandy Johnson