Spurred on by extra datapoints of Underwood typewriters left-foot numbers on The Database (Thank you James!), and now looking only at the Underwood 5 samples, there are enough points to reasonably map a relation. [Updated graph; showing 24 Underwood 5 numbers.]
It is not quite a linear fit (the portfolio mix of Underwood was evolving), but a polynomial fit gives a pretty good correlation. Using that fitted relation and the serial numbers from the agelist, then an 'auxiliary' agelist based on frame numbers can be created:
This agelist from frame numbers (a.k.a. the front-left foot numbers) probably has a margin of about a quarter-year either way. Note that after 1926 the first digit of the frame number can be missing, but the full number likely still stamped on the carriage side.
This 'auxiliary' agelist very likely can also give a year-estimate for Underwood typewriters that fall in other serial number ranges than the 5, but were built from the same frame-casting and assembly line.
There's more information still to be had from more data - e.g. there are hints that 1916 saw a significant, sudden shift in the Underwood portfolio -or factory set-up. Also there are hints on batch-sizes, and production buffering was not completely first-in first-out either.
I.e. as more frame-numbers become known, the data will improve and more information can be extracted.
But already possible is a rough "front-left foot agelist" :-)
[Update: volume estimates.]
After 1929 the data becomes hazy; maybe because of portfolio shifts or because of the market upheaval from the October stock market crash. After October the sales of expensive business equipment such as typewriters (or Elliot Fisher bookkeeping machines!) probably collapsed.
Nevertheless, between about 1905 and 1929 there seems a robust set of numbers; both for Underwood 5 serials and for all Underwood frames (on that typewriter-frame line, at least). This means an estimate can be made of the volumes and volume-share of the ubiquitous Underwood 5 for the company:
This shows the fluctuations of the overall sales, and also that the share of Underwood 5 (and 4) machines is more than 90% of machines in 1905, but by the end of the 1920s has dropped to about 60% of sales. It has become a less dominant product for the company - typewriter sales have become more diversified; the business market perhaps becoming more receptive to special features such as wider (and more costly) carriages.
Great work. With more WUS info, it'll provide some date info there. Need those late 5s near the ribbon switch over for the end of the run number. That will provide a closest yet approximation of how many 3/4/5s were made. Then add the ribbon switch update machines from 370 to 399 for a grand total. And this be the end of the "it is a rebuild number" 'theory'.
ReplyDeleteCurious for more WU numbers - would be neat if chronology could be created for these after a century!
DeleteWhenever I see a number-pair I add them to the set - it grows slowly, but grows. By the way, the 3-banks have a similar thing - seems that this frame numbering was just part of how Underwood did manufacturing..
Trying to get two additional WU feet numbers.
ReplyDeleteMore data
ReplyDeleteno 5 / 707920 / 843397
no 5 / 935533 / 1159914
no 5 / 714178 / 842404
no 5 / 2195629-5 / 2931080
no 6 4499188-11 / 787839
Thank you!!
DeleteAdded them to the dataset; updated graph with the extra nr 5's - machines are a bit 'clustered' still. The extra points hardly impact the agelist - that's maybe a very good sign; showing that it is approaching what's achievable.
Some pondering on nr 6's and 46's still. Am btw curious; does your 6 have the longer number stamped in the carriage-frame, under the right-hand nickel-plated cover?
Anyhow - many thanks! Approaching a likely-true agelist :-)