CAD – Target Enigma

[John HinkleyParticipant @johnhinkley26699]

Dave,

As you are still having trouble with the spring design tool, can I suggest that you go to the Traceparts.com web site and search for “tension springs” which will give you the choice of CAD models from which to choose.  Almost any format is catered for, including Solid Edge.  You may have to register in order to download, I can’t remember. If that is the case and you don’t want to, pick which one you want and PM me your email and I’ll download it for you and forward the file to you.

I use the Traceparts site quite a bit and, to save searching through pages and pages of parts, I often find something generically similar and then stretch or squash with the scale facility to obtain the size that I require.  Probably not the preferred way to do things, but it works for me.

John

 

[John Hinkley]

On John Hinkley Said:

Dave,

As you are still having trouble with the spring design tool, can I suggest that you go to the Traceparts.com web site and search for “tension springs” which will give you the choice of CAD models from which to choose.  …

 

Good tip!  I registered with Traceparts, found a suitable spring after a mildly tricky learner driver search, and downloaded it. Arrives inside a zip file, but not too difficult to extract the part into SE.

SE also offers 3dfindit.com.  Seems the user has to start by opening one of several catalogues, and you can’t just list ‘all springs’.  As I found what I wanted faster with traceparts, I’ll stick with it.

Many thanks,

Dave

[SillyOldDufferModerator @sillyoldduffer]

A bitty day yesterday, but useful progress:

Found a website with a good technical explanation of Enigma internals.  Including how the machine steps.  Quite interesting to see what I guessed correctly and what I got wrong!

Mocked up a SPDT switch made of strip-board to see how springy it is.  Result over short travel is encouraging.  Needs to be tested over a realistic long travel though and it might fail after many operations.

Got a better understanding of what might be going wrong with wheel lettering.  Many failures!  Next picture shows success, SE just did it, no aggro:

One cause of trouble is letter selection.  When hovering with the mouse, SE highlights snap opportunities hidden behind, and, if the part is in an assembly, it shows snap possibilities in other parts as well.  Chaos ensues if one of these is accidentally selected with the letters, and it can  break the model!  When letters are embossed correctly by Normal Protrusion, the operation can be undone.  However, if the emboss was incorrect, perhaps because of an accidental extra selection, then Normal Protrusion is damaged internally, and it may be necessary to delete everything.   Also discovered that letter height appears to be nominal – 6mm Ariel is not the same height as 6mm DejaVue.

Dave

[SillyOldDufferModerator @sillyoldduffer]

I’ve started the Mk2 model, this one approximately full size, and benefiting from new information received.

Turns out the rotors and rotor assembly are more complicated than I thought, and though closer, my latest attempt is still off target.   More work needed!

Long list of corrections to do!  For example, I’ve separated the odometer drive pawls along their axle with brass spacers, when the original uses coil springs.   The coil springs push the pawl into the ratchet as well as space the levers.  My rotors are too fat,  and the roller arms are tensioned the wrong way round.  I guessed extension springs, a close look at real pictures suggests compression springs.

The more I dig into Enigma the more impressed I am by the original design.  Tempting to have a go at the British  Typex which is even more elaborate, picture from Crypto Museum:

History records that the Allies captured several Enigma machines and the even more valuable key management documents, both used to great effect.  Although Axis codebreakers did well in the early part of WW2, they failed to make any headway against Allied rotor systems.   Did Germany ever capture a Typex?  And if so, what did they do with it?

Back to the grindstone…

Dave

 

[SillyOldDufferModerator @sillyoldduffer]

WW2 continues in Castle Duffer with mixed progress on Project Enigma.  Added a battery box, plugs, key platform, lamp holders, and many tidy ups.   Keep finding new subtleties in the original machine and more Solid Edge feature.   Decided to follow Jason’s advice and CAD my own springs:  partly for the learning, and partly because searching catalogues is boring!   (Back to the catalogue if I ever build this for real, I will have to buy them!)

The real machine is built on pillars, and I think my version is ugly:

Also, unsolved problems with the keys and how on earth I will I squeeze 26 switches into the space available.  There must be 3 banks of switches in the photos and I can only see two.  Possibly one is double-banked in some way.

Still have to debug why the mechanism doesn’t animate properly, design the lid, add a rheostat, and surround the whole with a wooden box.  And I’m sure there’s plenty I’ve missed. In theory I could CAD the wiring loom.   Tempting after a tiring day to develop a closed box and claim there’s a finished Enigma inside that could be shown working except I’ve lost the key.  The beast needs beautifying too, the parts are all rather blocky – unfinished.

If anyone thinks CAD is easy, this version contains 74 unique parts in 21 sub-assemblies, all mated together and sized in a geometry allowing the thing to animate correctly.  Fasteners not included.   This is not a drawing!

Sadly for me Enigma can be emulated on a £4 Arduino and someone else has already written the code…

🙂

Dave

[rjenkinsgbParticipant @rjenkinsgb]

Very impressive CAD work! Mine is limited to single relatively simple parts for 3D printing.

A couple of thoughts on the electrical parts:

For the brass contact pins, could you use small brass screws, eg. cheese head for flat and pan or round head for the matching ones. You can get unslotted round head, used to look like rivets. 14BA is about 1mm thread diameter.

If you don’t mind using off-the-shelf parts, 2.5mm or 3.5mm jack sockets could be used for patch sockets; the most basic mono three terminal open frame type have a normally contact that’s opened by inserting a plug. You can use a solid brass pin for the plug, for external appearance.

 

[SillyOldDufferModerator @sillyoldduffer]

Thanks for the suggestions Robert, I’m open to them!

There are three versions of the project in my mind, and the boundary between them isn’t nailed down.   They are:

1. Started with a freelance version of Enigma, based on blurry photos, and limited information, so lots of guesswork & reverse engineering required.  I modelled at about 1/3 scale with half an eye on making a real one and that was a mistake because small parts become a watchmaking challenge that I’m unfit for!
2. Bought a book with better photos and descriptions.  Quite pleased to find my solutions were generally close to the original, but no surprise that my freelance design was wrong in many details.   So I switched to a full-scale model with parts closer to the original.  Still lots of reverse engineering needed because the book has no plans – I don’t even know how big a real Enigma was.   It’s all based on the size of the keyboard in the photos.   This is what I’m concentrating on at the moment.  Everything apart from the battery box, which is a sheet metal job, could be made in a home workshop with a small lathe and mill.  The result might pass casual inspection as a replica, but wouldn’t fool an expert – too many small differences.
3. The third version if I get that far will be production minded, specifically replacing metal as much as possible with 3D-printed plastic and standard components.   Your suggestions fit neatly into this camp, and is the most likely to made real – less work, time and money.  The result will look modern.

Using mono jacks is a good way of saving time, ditto lamp holders, or even LEDs.  The amount of work in replicating the original components is significant, here’s the equivalent of the mono-jack, actually a little more complicated than it appears because there are two insulated pushers inside the sockets:

And the German lamp holders are remarkably solid, perhaps intended to be Milspec shock-proof:

Another possibility is the complexity is due to design starting in 1919 before standard lamp holders and such were available.  Though I thought telephone systems had them by then.  Right pain to make though, especially in a workshop not set up for production work.

Part of the endeavour is improving my CAD skills.   Mostly I do the same as you – CAD single parts for 3D-printing or metal-bashing, keeping it simple.   Very taken with assembly though: CAD makes it much easier to design multiple parts working together.   And goodies like 2D plans and STL just pop out at the end.  All that’s needed is the time and inclination to learn how to use the tool…

Thanks for the ideas, much appreciated.

Dave

 

 

[SillyOldDufferModerator @sillyoldduffer]

As predicted putting the covers on hides a multitude of sins!

Both covers took about 15 minutes before I was torpedoed.   The rotor assembly was too low, meaning an operator couldn’t set the spur wheels or read the rotor letters.   Led to another ramble in the rough working out how to lift it without breaking every moving part in the rotor assembly, scary!  Can’t just be jacked up because the rotors are linked to the thumb-wheel locks, and the odometer drive pawls, and they’re connected to the keyboard. Fixing that lot took a couple of hours.  Need to increase the diameter of the spur wheels and the rotor letter wheels, both fussy jobs.  Solid Edge doesn’t seem to allow objects modified around the circumference to be edited in the usual way, hmmm.

Also added the lamp letters, and struggled to paint them black.  Q and O aren’t in-filled properly even though other letters like A B & D took the paint correctly.   Possible software bug.

Next challenge is the plastic light shield.  Fits under the lid I guess to concentrate light under the working bulb and stop it confusing the operator by shining through adjacent windows.  Looks like 26 double curved bevels moulded in a plastic plate and I’m not sure how to model the curves.

Dave

 

 

[SillyOldDuffer]

On SillyOldDuffer Said:

[…]  – I don’t even know how big a real Enigma was. […]

 

I presume you have seen the photo on this page, Dave … but just in case:

https://www.codesandciphers.org.uk/lorenz/fish.htm

MichaelG.

.

See also:

https://thehistorypress.co.uk/article/how-lorenz-was-different-from-enigma/

[SillyOldDufferModerator @sillyoldduffer]

That page is for a Lorenz, a different machine, but the size is still uncertain.  I think the Lorenz was bigger and heavier than an Enigma.  These ladies give an idea:

My book covers Lorenz up to a point.  Enigma was man portable, approx typewriter size, so could be used tactically and in ships and submarines.  Needed two men to operate, ideally 3, and the handwritten output was handed to a radio operator who sent it in morse code.  Clumsy!

Lorenz was a teleprinter system, sending 6 bit baudot code ideally over a landline connecting fixed headquarters.   One man operation, no morse, except it took a lorry to move one.  However, because landlines were often cut or not available, the Nazi’s were forced to use radio links.   A major communication centre in Konigsberg, then East Prussia, now Russian Kaliningrad, linked Berlin to Norway, Finland and the northern Russian Front by radio, all intercepted in the UK off the back of the aerial.  The Lorenz cypher, in theory stronger than Enigma but flawed, was also broken, again mostly due to operators breaking the rules.

Anyway, not found a source giving measured dimensions for any of these machines. Based on photos with people in them Enigma was about the size of a typewriter, so I’m only accurate to within a hands breadth!   If I was well I’d make contact via SMEE and drive to Bletchley with a camera and tape measure.

Dave

 

[Michael GilliganParticipant @michaelgilligan61133]

Sorry for wasting your time, Dave

… Yes, I knew it was for Lorenz, but it had a nice [albeit low-res] photo with a chap’s hands near to the machine.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

… Perhaps this is more to your taste:

https://www.cia.gov/legacy/museum/artifact/enigma-machine/

MichaelG.
.

[ no I haven’t spent the last six hours searching  🙂 ]

[Michael GilliganParticipant @michaelgilligan61133]

See also:

http://www.mlb.co.jp/linux/science/genigma/enigma-referat/node2.html

MichaelG.

.

Edit: __ in case anyone is interested: Jack Copeland’s book [which includes Turing on Artificial Intelligence] is available for download, here: https://ia801702.us.archive.org/19/items/turing_202010/Turing.pdf

[Michael Gilligan]

On Michael Gilligan Said:

See also:

http://www.mlb.co.jp/linux/science/genigma/enigma-referat/node2.html

MichaelG.

…

Brilliant!  “The dimension of the machine are about 13.5 * 11 * 6 inch. The weight is about 26 lbs. ” or as the CIA put it 32 cm x 26 cm x 15 cm. (L x W x H)

I’m on the wrong computer to check all the dimensions but know my version is 30cm wide, a 15% error.  Might be able to correct the problem, but I fear it will generate dozens of changes.  Solid Edge can only scale individual parts, not an assembly, so no shortcuts.

Cheers,

Dave

[Michael GilliganParticipant @michaelgilligan61133]

I think we can take this as definitive:

https://www.dpma.de/docs/dpma/veroeffentlichungen/de416219a_chiffriermaschine1918.pdf

MichaelG.

.

Ref. https://www.dpma.de/english/our_office/publications/milestones/enigma/index.html

[Michael GilliganParticipant @michaelgilligan61133]

Sanity-Check on the dimensions:

https://www.computerhistory.org/collections/catalog/B197.81

MichaelG.

[SillyOldDufferModerator @sillyoldduffer]

Health permitting still plodding away at Enigma, 95 parts in 26 assemblies and rising.  Going well but finding many misunderstandings and missing details when carefully comparing my guesswork with the real McCoy.

For example, I sussed that the rotor assembly is released by the operator turning a handle on a cam,  and designed this:

The real cam, found in a photo, is like this, held by means unknown inside the reflector case:

Modelled the rheostat block, used to control lamp brightness:

Rheostat problems:  my photos show 8 contacts, not 5, and only 4 are needed. Something not right.  Assumed ‘Batterie dki” was two settings, and it’s one: “Battery Low” in English.   My spring contact is much less beefy than the German one, and my switch has no click stop, ttoo simple.

Text labelling issues galore!  I haven’t found a suitable font, so words and numbers aren’t authentic.  Don’t have a font that will render the German eszett symbol ß in Solid Edge.   As in “Ludendorffstaße 6”.

Even the wooden box is complicated.  Done piano hinges, but not mortice joints, or the leather strap on the back, various clips, the Brass lock, or the slider arms that prevent the lid over opening.

 

Having trouble with SE’s Part Painter, which applies randomly.  Also getting SE to render decimals with a point rather than a continental comma separator is getting my goat.     Another go at the Spring tool failed.  Also, why animation isn’t working properly, except probably me not setting the mates spot on and/or removing interferences.

Many other cosmetic issues if this was to be an accurate replica: my plugboard plugs and sockets are a shade too big, how to spring the rotor pins, colours, accessories and many small details.

I expected this actual size model to be quick and easy.  Not so. Small things wasting loads of time.  I’m a fair way off coming up with a metal/plastic hybrid model that could be 3D-printed (mostly).

3D modelling has taught me a fair bit about pre-WW2 German design.   Asking why the original differs from my version often reveals German engineers attending to details I hadn’t noticed!   Apart from not using modern off the shelf components that didn’t exist back them, Enigma is competently designed.

Pleased at how close my version is compared with the real thing: mine weighs 9.6kg (21.6lb), compared with 26lbs quoted in Michael’s example.

Dave

 

 

[SillyOldDufferModerator @sillyoldduffer]

Learned more about driving Solid Edge with fewer accidents.    Classic me thinking the software works way ‘A’ when it actually works way ‘D’, and takes no prisoners.   Good progress on the wooden box, and also experimented with Keyshot.

SE produces good rather than photorealistic images and I’ve been sharing them as screenshots, so nothing exciting, like this:

Keyshot is a render engine, designed to process images in a multitude of ways.   It reads the Model (not a copy of the image), and displays it in basic form. Then the user can place lights, backgrounds, colours, and apply all of the adjustments available to a camera – depth of field, vignetting, etc.  There’s a lot to it!  Chief advantage to me is that rendered images can be much higher resolution than SE and tarted up to improve appearance.   Enigma was painted in Black Crinkle, which Keyshot can do.  Can’t see crinkle on the crunched down forum image, but it does show the wooden box looks less dead when rendered as Light Oak.

Zooming in shows the crinkle:

SE does the usual 2D engineering stuff auto-magically in glorious black and white:

 

Individual part, 1 of 99, dimensioned:

Or as an STL file for CAM…

Although SE did most of the heavy lifting, for example by lifting new dimensions from parts already in the model, not requiring me to keep track, there are still 14 pages of handwritten notes and doodles.   However, once the tool is conquered, CAD is orders of magnitude more efficient than 2D draughting methods.   If only it didn’t require so much effort to learn!

Dave

 

 

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