From the mailbag: Fraction of an Inch Adding Machine

Usage 3: First operand
Karen wrote in to say:

Thanks so much for the 2007 article on Make your own 1952 Fraction-of-an-inch Adding Machine. I inherited one of these and was delighted to find information about it on your web site. Now that I have explored your web site a bit, I am adding it to my favorites!

4 thoughts on “From the mailbag: Fraction of an Inch Adding Machine

  1. This is so awesome! I remembered seeing it somewhere but didn’t realise it was your own site. I’m inspired to have a go at making a laser-cut version – I’ve recently been playing around filling laser-etched lines with Dykem layout blue and then scraping off the excess with a razor blade/sandpaper to leave a nice crisp line. I’m imagining a couple of nice white Delrin discs with etched markings…..

  2. If you took a stand and shifted all your kits metric, there would be no issues with adding 9/16″ and 11/64″

    Fun fact: the only 3 countries NOT using the metric system are USA, Meinma and Liberia

    1. Really? This again?

      With all the great things to say about the metric system, your best argument boils down to “I don’t want to learn how to add fractions.”

      * If we “took a stand” and shifted all of our kits metric, we would be able to advertise things like pin spacings of 2.54 mm, instead of 0.1 inches. Right. Huge improvement.

      * Exactly where has one of our kits suggested that you add 9/16″ and 11/64″? That’s baloney, and you know it. We found an interesting artifact (back from the days when fractional inches were common) and wrote about it. If you don’t think that a fraction-adding slide rule is interesting, you don’t have to. But using it as an excuse to bash us (or americans in general) doesn’t exactly do any favors for your argument.

      Fun fact: The US joined the meter convention over 110 years before New Zealand.

  3. woohhh I think I touched a nerve. Just trying to point out its easier, no need to get upset


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