Enigma progress update.

July 15th, 2017

Right, an update and another badly made film!

I am at the point now where the basic mechanism of my Enigma machine is proved to work. I don’t have a keyboard yet but the mechanism the keys operate on, the pawls and rotors and so on, are all working mechanically. I won’t do the electrical parts until later.

Apologies for the bad filming and the gloves. My camera is not great and it’s bloody cold here!

In other news I have started a new job, back to software testing and eventually test automation. It’s nice to not be going backwards financially again! I am working in the city for a startup based on The Terrace which is amusing as when I first moved to Wellington I lived on a flat on The Terrace and used to travel by bus to Miramar to get to Weta each day. Now I get to do the exact opposite and travel from Miramar to The Terrace. I find working in town is great, even with the commute (30 minutes on the express bus), since I get to use the library again and then get time to read. So I have been reading everything I can about Bletchley Park, Enigma, Ultra, cryptography and so on. All fascinating stuff.

I am currently reading “Enigma: How the German Machine Cipher Was Broken and How It Was Read by the Allies in World War Two” by Wladyslaw Kozaczuk. This is a great book explaining exactly what the Poles did with Enigma, something that has been woefully under reported over the years. Basically, before the war, they completely broke Enigma and it was their work that really helped the British with their own code breaking during the war.

The three mathematicians were Marian Rejewski, Jerzy Różycki and Henryk Zygalski but there were others who played a huge part in it all including French military intelligence. There is a brief description about it all here: https://en.wikipedia.org/wiki/Biuro_Szyfr%C3%B3w

The story of what they did and and how it all came about and what they actually went through is totally fascinating. It would make a excellent film if they stuck to the facts (so don’t let Americans make it and if the British do, someone keep a close eye on them). As I learn more and more about the history behind the Enigma machine the film The Imitation Game annoys me more and more! But I suppose I have it to thank for getting me interested in all this in the first place.

I am currently looking for a copy of that book (the 1984 edition – the later reprint isn’t as good) but it’s quite expensive!

Anyway, these are some close up pictures of bits of the machine to make up for the blurry, wobbly film!

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Printing the new side piece with extra stiffening. And the mounting foot printed as a separate piece.

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The pawls with brass weights so they always fall into the rotors. You can see the little buffers they pivot on when the keys aren’t pressed. On the real machine the pawls are spring loaded but I was too lazy to do all that! Given my Enigma machine doesn’t have to operate in the back of a half-track while invading France I feel it is OK to do a little simplification!

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The sprung loaded pieces that keep the rotors in their fixed positions but that allow them to ‘click’ around. I still have a little wracking on the two brass shafts that these spring loaded levers work against so I will add a printed stiffening piece joining the two brass tubes to the right of the levers in the picture above.

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The reflector and the lever and ramps that push it into the rotor stack. The brass rod at the top stops the reflector from rotating.

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The keyboard plate axle mount. The base plate is printed with raised edges into which the mounting brackets fit tightly against to ensure the positioning is totally accurate.

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Showing how the pawls engage the ratchets on the rotors. You can see in the last picture how the left most rotor is in it’s notch position which means on the next key press the middle rotor will move along with the first. The third rotor won’t move since it’s pawl is riding on the edge of the rotor and so it can’t engage the third rotors ratchet to move it.

So, next I want to start looking at the keyboard and how that will work. I have a ton of small micro switches so need to work out how to make the keys, how to add springs so only the key being pressed drops and how to make it so the key travel first moves the rotors and only then engages the switch. I should probably order a bunch of spring off Aliexpress now I think of it!

I am also going to reprint the reflector and entry wheel at some point. Each has a tiny lip on the outside edge that catches the rotor stack when you try to insert/remove it. It doesn’t affect the operation of the machine, it just annoys me! I will also add in pockets for more hex spacers to attach the bolts to. Currently the plastic is just tapped for the screws and while this works I like the idea of having nylon threaded inserts in there better. That method worked very well on the rotors themselves.

Finally it is hard to say how many hours I have spent on this project so far. Learning Fusion 360 takes time and there is much printing of parts, seeing how they work then modifying them. I don’t think any part I have made is exactly the same as in the real Enigma. Everything has to be redesigned and remade.

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This is my box of experimental parts. There is a good 1.2kg of printed plastic in that so far. These are all parts that didn’t work in the machine, not failed prints. I actually get very few failed prints these days. The printer is working extremely well! I happily leave it going for days at a time. With a web camera pointed at it and Repetier server running on it I can remotely monitor and stop it if needed.

One Response to “Enigma progress update.”

  1. Flying Faller Says:

    Is there any chance you will release the 3d models? I’ve been looking into making an Enigma Machine for a while now but I haven’t found a cheap and accurate solution until I stumbled upon your videos and site.