That’s an interesting offset driver comparison. Both have the same model number. Hmm.
I’m actually trying to educate myself on the JP Danielson date codes. So far just tricking out what AlloyArtifacts has to say about it.
The 312.1 is something else, not a date code.
Looks like the first step is to guesstimate the decade from the construction details, patent stamps, letterform. The LNN (letter-number-number) date code system started around 1939. The 12pt broached hangerhole puts a cutoff date in 1947, but the “typewriter font” letterform cutoff is 1942.
Then the last digit of the year is the right-most number, in this case “0.” Only 1940 falls between 1939 and 1942 (or even 1947).
The middle number is always 1-12, so I assume 1=January...12=December. (Debatable, I’m sure.) So 11= November.
Now the exciting, and possibly pointless part: what does the leading letter mean? In my example, “K”.
I analyzed 61 examples represented on the AA site, and my conclusion is the letters are production days per month. Probably none are Sundays. Also, AA has NO EXAMPLES of “Z”. Maybe they don’t exist, or maybe they’re just more rare. It seems to me that 25 (or 26) letters is just about enough to cover a 6-day workweek four to five times per month. How exactly they were used, I’m not sure. If “A” is the first production day in a month, the month starts on a Sunday, Monday or Tuesday and has 31 days, seems you’d need that Z and then another “letter” after that! And what to do with holidays?
But that’s assuming a Gregorian calendar. I recall there were
“rational” calendars used by some businesses (Eastman Kodak) even into recent decades (1989), which might better fit the A-Y workdays pattern.
From the 61 examples I used from the AA site, J&P occurred 5 times, K 4, ABCHLOSTX 3, EGQUVWY 2, DFIMNR 1, Z 0. It’s not a very large sample size for statistical analysis, but they do seem to bunch up in something like a moire pattern, so there appear to be two cycles colliding in this sample.
I think a few thousand examples would help, but who has the time to spare? It’d be really nice if someone discovered an internal Danielson document from 1937 or 1938 that explained it all. I think it’s possible to figure this out, but not worth the effort. Certainly the benefits are less impactful than breaking Enigma.