M-94 Cipher Device (WWII US Army)

thingiverse

Google Image the name to find lots of photos of what this is supposed to look like completed. Still needs a bit of tweaking: I haven't worked out how to do threads yet, hence the optional knob with hex hole in it for inserting a 1/4 inch nut. Also a shaft end with a square hole through it to take a 1/4 inch coach bolt. Obviously a cipher device is not much use without the letters on it, but not only will putting all the letters and text on the parts take ages, they'll be so small that few extruded-filament printers will be able to capture the detail at actual size (this thing is tiny). Instead the idea is to print them out on paper in columns and cut out the strips to stick onto the disc perimeters. Of course you need to make 25 of the 'disc blanks'. And I would forget about the shaft and just use a length of 1/4 inch threaded rod, or a 4 1/2 inch long bolt. I'm speaking in ye olde imperial measurements, of course, because this gizmo was originally designed in America before WWII. Print Settings Printer Brand: MakerBot Printer: MakerBot Replicator Rafts: Yes Supports: Yes Resolution: .02mm Infill: 20% Notes: Since the real things are made of aluminium, this would look best printed in silver filament. If you can get the stuff to stick to the bed or the raft. Not that I'm having trouble or anything... Post-Printing Those steps along the indicator arm could be avoided if printed on it's side. Prints OK on the old Makerbot at work, though the 'silver' filament I'm trying to use is doing odd things on the first couple of layers. But dimensions are good and the parts fit together. Have also tried with a U-Print: outrageous cost and lousy resolution, but the support comes away more cleanly and easily. I've included two files for printing out the lettering to go on the discs. One is a full Photoshop document for those who might want to fiddle with it, the other as a JPEG for those without Photoshop. The first/top letter (or number) in each column just identifies the disc and should be cut off. Actually, this identifier is superfluous, since each disc can be identified by the first letter to appear after the 'A'. Cut the strips 3.5mm wide (find the 'W' in each column and cut a smidge outside it.)(Be sure to use a metric smidge, not the old imperial smidge, which is a gnat's bum too wide.)(Metric gnat's bum, obviously.) Strip length from top to bottom should of course match the circumference of the discs. About 115mm worked for mine. You should be able to cut at the bottom edge of the top letter/number (removing it) and at the bottom of the last letter. When sticking the strips to the discs, note the 'A' always goes adjacent to the little bump inside the rim. A final layer of clear tape over the top will protect the printed lettering from wear during use. Correction - I tried to include a JPEG, but it didn't show up as a 'file'. I applied 'magic tape' over the lettering before cutting the strips to protect them. This is silver self-adhesive stuff that looks just like aluminium with the frosted tape on it. This is fiddly and tedious. But worth it! Be careful to glue the indicator arm to the indicator disc at a perfect right-angle. I'm using a 5inch long coach bolt here because I'm lazy and found one close to hand. You could paint the parts silver, but it wouldn't stand up to much handling. Better to print the parts in silver, or even pale grey. How I Designed This There are plenty of photos of these gizmos on the Net, but very few dimensions, and surprisingly few good pics that show the details clearly. So I've used the few dimensions I could find (special thanks to a member on the cryptocollectors Yahoo group) and scaled from the photos. As a result, I dare say dimensions are slightly out, but I think it looks reasonable. Any accurate dimensions would be greatly appreciated and incorporated into future versions.