Wooden Addiator plans?

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.
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Joe Bramblett, KD5NRH wrote:

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.
Dave WD9BDZ
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Sorry no plans but I do have an Addometer with its original leatherette case. Mine is about 12" long and probably would not fit your pocket very well.
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Talking about abacus ? I bet the third from the bottom on this page : http://www.vintagecalculators.com/html/mechanical_calculators.html
Kingson Four-Rule
Martin
Joe Bramblett, KD5NRH wrote:

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Best regards
Han
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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. ;~)
http://www.vintagecalculators.com/html/exactus.html
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. ;~)
John
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Lots of them still available on eBay - enter mechanical calculator 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 section. Kerry
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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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