Go to the Typewriter Database and click on Olympia. Then, rather than clicking on your model name to see the machines others have uploaded, scroll down and you'll see the models listed for Olympia and serial numbers by year. I think mostly it's the serial number range beginning with a certain year.

Thanks!

Typingrav wrote:

I'm having a similar problem. I went to the Underwood page on the database, but the serial number-686970911 doesn't seem to match any of the photos on the site.

Serial #6,814,000 to #6,900,000 = Jan. 1951
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The first thing is that you have to drop the last two digits from that number you posted because it indicates the platen length and isn't part of the actual serial number (there should have been a hyphen in front of the '11' on your machine).

And you need to ignore the photo in the database because it isn't representative of all the standard model variants that existed between 1931 and 1968.

As for the model itself, it's an Underwood Rhythm Touch. The database tends to identify models by how they appeared in a manufacturer's internal documentation, but I prefer - in the absence of a model badge on a machine - to describe typewriters by how they were described/labeled by a manufacturer in their marketing of the typewriter to the public.