There was a brief period through the 1960s into the 1970s when the last word in electronics was the calculator. New models sold for hundreds of dollars, and owning one made you very special indeed. Then the price of the integrated circuit at their heart fell to the point at which anyone could afford one, and a new generation of microcomputers stole their novelty for ever. But these machines were by no means the first calculators, and [What Will Makes] shows us in detail the workings of a mechanical calculator.
His machine is beautifully made with gears hand-cut from plywood, and follows a decimal design in which the rotation of a gear with ten teeth represents the numbers 0 to 9. We’re taken through the mechanical processes behind addition, subtraction, multiplication, and division, showing us such intricacies as the carry lever or a sliding display mechanism to implement a decimal equivalent of a bitwise shift multiplication.
We have to admit to be particularly impressed by the quality of the work, more so because these gears are hand made. To get such a complex assembly to work smoothly requires close attention to tolerance, easy with a laser cutter but difficult by hand. We heartily recommend watching the video, which we’ve placed below the break.
Meanwhile if you’d like more mechanical calculators, take a look at one of the final generation of commercial models.
I have the remains of a friden computerized accountancy desk with pegboard programming and a IBM model C typewriter for input/output. internally the brains of the machine was a friden STW10 mechanical calculator, with every button needed activated by a solenoid and the output read back with decimal encoders. it must have been from the late 60’s and Friden didn’t like electronics at all, simple relais and mechanical calculators was all they had and used. unfortunately the machine was broken up for parts decades before i could get my hands on it.
Regardless of its state, you should photograph it and share. Sounds fascinating
Agree!
It’s a wooden Curta!
https://curta.org/
That is awesome .. and true dedication to a project. Impressed. Those guys that came up with the ‘first’ mechanical box back in time, as in ‘invented’, is mind blowing (at least to me). The inventor and the craftsmen to make it so. Really cool.
Now, I suspect, one could just CAD your idea up. Fit the parts on screen, test in software, and then 3D print the parts and test results and iterate as mechanical problems are found. Probably make a much smaller, lighter box in the process.
You put first and invented in quotes and I’m reminded of the antikythera machine; doubtless it was not the first of its kind, it is clearly too advanced in both design and technique. I wonder what the first one was. Most likely we’ll never know
I’m not a maker, so could you explain what you mean by test in software?
Do modern CAD programs simulate motion, like inter-meshing gears?
That is a thing, yes.
From what I understand, some 3D CAD applications can. For example the Boeing 777 airplane was build entirely in 3d CAD and all parts test fitted, checked for clearance, etc. before a part was ever machined (reference https://en.wikipedia.org/wiki/Boeing_777 ). Neat stuff. I am not a ‘real’ CAD guy as I only dabble in freeCad and do simple stuff!
Whew! Don’t let them outsource it to the wage-depression squad next time and it should be fine
Very cool! I’m blown away that this was all cut by hand on a scroll saw. My lazy a** wouldn’t have even generated the toolpaths for a CNC. Kudos to you!