Surely somebody remembers these pocket mechanical add/subtract calculators.
I was thinking of trying to make a large one from wood as a math teaching
aid. Has anybody here done it? The mechanism is pretty simple, and it
looks like it would be easy to build, but we all know how the easiest
looking projects can turn into a mess when it comes to actual execution.
I can't give you any help on designing and building one but I seem to
recall seeing one years ago. This looks like an exciting project though.
If you do make one please publish your project on a website somewhere
and let us know how it goes.
I had one like that when I was a kid. I think it was the Exactus model shown
on the web site... the instruction manual looks familiar to me! I still have
a circular slide rule with the case and instructions... I got the slide rule
just as the TI pocket calculators were starting to drop from the $400-500
range to about $100 in the early to mid-70s. I figured the slide rule would
be a neat relic. Wish I'd realized that about the Additor type calculator.
I can recall how carefully you had to stick the stylus in the little notches
and move them... To get accurate results you really had to pay attention and
have a feel for the tool, much like using my hand tools vs. running things
over my jointer or through my planer. ;~)
Lots of them still available on eBay - enter
in the search box, and the bottom of the page will show several Addiator
type devices in the eBay stores section, as well as a couple in the auction
I inherited granddad's log-log duplex Pickett slide rule. It was good for
some funny looks when I used it on a radio exam. I still use it from time
to time when I'm stuck without a scientific calculator.
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