I Built a Mechanical Calculator [video]

https://www.youtube.com/watch?v=E0pJST5mL3A

by lispybanana • 1 year ago

127 33 1 year ago

whyage• 1 year ago

Great work, excellent video.

tombert4• 1 year ago

I love thinking about the "what if?" universe where we never figured out semiconductors and transistors, but still had roughly the same level of human progress. Would everything be clockwork like Syberia [1]? Would we have something akin to iPhones but done entirely with electro-mechanical stuff with antennas? I guess this is sort of the appeal of something like Steampunk.

Mechanical calculators are ridiculously cool to me. If I ever become an eccentric billionaire, I really want to buy an original Curta calculator [2], just because I respect the genius and engineering required to design such a thing.

The one in this video is also very cool. Very satisfying to watch all the gears turn at once.

[1] https://en.wikipedia.org/wiki/Syberia

[2] https://en.wikipedia.org/wiki/Curta

sebzim4500• 1 year ago

You don't have to be a billionaire, I got a Curta mark I for ~£850 on ebay and it's like the world's greatest fidget toy.

tombert4• 1 year ago

£850 is actually cheaper than I thought it was, but it's still a bit much for me to justify right now. If I spent a grand on a fidget toy, I think my wife would be pretty mad at me.

Whatever patents that they had have to be expired, I kind of wish someone would make reproductions. I know there's the 3D printed ones, which are cool in their own right, but since 3D printers aren't super precise the parts have to be huge to compensate. I want as close to a one-to-one reproduction as possible, but I guess there's not much money in it.

fooker• 1 year ago

Maybe without semiconductors we would stumble upon something better sooner.

Maybe optical/biological/quantum computing.

bnkd_• 1 year ago

Great work !

renlo• 1 year ago

Great video, I really enjoyed how down to earth it was. It reminded me of The Secret Life of Machines [1], where we get to peek behind the curtain and see how seemingly "magical" machines (in your case a digital computer) emerges from simple fundamental concepts.

[1] https://en.wikipedia.org/wiki/The_Secret_Life_of_Machines

theendisney• 1 year ago

You can just continue the division by inputting the remainer i think?

rtkwe2• 1 year ago

I don't know if he mentioned, the name doesn't show up in the transcript, it but this seems to be very close to an unrolled Curta, the main difference being that it doesn't use 9s complement for subtraction so it has a more complex bidirectional carry mechanism. Otherwise the function is very similar down to shifting the turns and output accumulator to multiply the entry number. The big drum he makes many of is just one in the Curta that actuates every output dial through a full rotation.

9s complement makes subtraction extremely satisfying on the Curta because it causes a carry on (almost) every single output and turn accumulator dial.

WilliamG523• 1 year ago

Hi, I made the calculator and this video. As I discuss throughout and particularly towards the end of the video, my design is based on Thomas de Colmar's Arithmometer (~1820-1860) and Leibniz's Stepped Reckoner (late 1600s), both of which predate the Curta (1930s). Or rather, the Curta is a super cool and elegant refinement of those (and other) designs. I think it is more accurate to say the Curta is like a rolled up version of those (and my) calculator.

The "big drum" you mention is sometimes called a Leibniz Wheel, though this naming convention is misleading in some ways: http://journals.cambridge.org/abstract_S0007087414000429. As that article argues (though I disagree with some points), the history of calculating machines is more nuanced than a linear progress narrative suggests. So, I tried to keep my narrative a little tighter and not go much into the calculators of the late 19th century and the designs in the 20th century like the Curta. Also, the Curta's (awesome!) story has been told many times, so I did not feel the need to go into it. Sorry to go on this long, but I think this history is fascinating and how we tell it speaks to how we understand how technology changes through time.

gregschlom• 1 year ago

Just wanted to say, fantastic work and video. I really enjoyed watching it.

glth• 1 year ago

Great video! Very instructive.

mjd• 1 year ago

Your machine, and the video, are astounding. The complexity and precision of your design, and the clarity of the explanation were all marvelous.

Thanks so much for bringing this to us.

MrMcCall• 1 year ago

I just want to say that this is one of my favorite YT videos of all-time. Content, presentation, project, execution, pace, music : all perfect. That is NO exaggeration. You have made my day better, young man.

Well done, young sir! Thank you for your hard, difficult work, and sharing it with us.

ETA: And you got a lol from me at the end!

Animats2• 1 year ago

The carry propagation hardware is the hardest to make work right. The low-digit add has to power the entire chain of carries. As the number of digits increases, it gets harder to do that, because so much mechanism has to be pushed.

There are carry mechanisms which use an external power source for carry propagation. Babbage's Difference Engine has one.[1] All the pending carry values are stored in a latch for each number wheel. Then a cam system applies the carries one at a time. This scales to large numbers of wheels.

[1] https://youtu.be/vdra5Ms__9s?t=247

rtkwe2• 1 year ago

You can definitely feel it when doing subtraction on a Curta, there's significantly more drag involved in it both because you're generally adding a larger number so more teeth interact but also the wave of the carries going around. However the low digit doesn't have to power all the carries though on a Curta because all the carry does it shift a gear up that then interacts with a single tooth (or 9 during subtraction) on the drum that performs the carry for the next digit up.

There's a whole page of Curta info [0] and a 3d simulator [1] where you can see how similar the setup is and some of the ingenious tricks to fit all of the functions of this machine into a little larger than a grenade sized package.

[0] https://www.vcalc.net/cu.htm

[1] https://www.satadorus.eu/x_ite/yacs_2_0/yacs_2_0.html

WilliamG523• 1 year ago

Yeah carry propogation is tricky. Matthew Jones (the historian who wrote the book I discuss in the video) calls it the "Sufficient Force" problem. Babbage certainly did solve the problem, but so did Thomas de Colmar in his calculator and all the derivatives it spawned (including mine). This is because the mechanism that performs the carry is driven by the central drivetrain and furthermore each column is offset in the cycle (by 1 tooth of the drive sprockets) so that carries ripple, instead of happening all at once. See 20:35 in the video. This means that a low-digit add does not directly power the entire chain of carries, it just triggers them. And furthermore, you can basically keep adding columns without worrying about the force increasing drastically: Thomas de Colmar even made a "piano Arithmometer" with a 30 digit capacity.

While carry propagation is certainly a hard problem to solve (just ask Leibniz), I had much more difficulty getting the zeroing mechanism to work smoothly - in a way it's a similar issue because you need to move a bunch of parts all at once, which from a force perspective is difficult.

Oh I should mention that Pascal also solved the sufficient force carry propagation issue in the Pascaline with his "sautoir" mechanism.

matt-attack• 1 year ago

Yep. The whole time I kept thinking, “oh so that’s why I have to that to the curta” or “oh so now I get what’s happening in my curta!”

orbital-decay• 1 year ago

What is the simplest way to do mechanical logic? Without all those fancy looking gears. I wonder how far it can go if you actually optimize it.

tocs3• 1 year ago

I have had an interest in building a mechanical computer for a long time. It has not ever gotten farther that some research into what route to take. There are lots and lots of simple logic mechanisms (many, many in use in real world applications). It can go as far and be as capable as you have time for.

jecel• 1 year ago

An interesting option is rod logic, which is the mechanical equivalent to a PLA (programmable logic array).

https://www.jamiekawabatarobotics.com/?p=40

pgarza00001• 1 year ago

https://www.youtube.com/watch?v=G_SC7oWL78A

The Whiffletree was used in mechanical calculators. It's an interesting way to encode digital data mechanically.

drcode• 1 year ago

the madness of cutting hundreds of gears by hand, many with a 45 degree bevel, I couldn't even imagine.

madness!

simonjgreen• 1 year ago

For a second video, this is amazing. It also took me to their first video which is a mechanical hand, also out of wood https://youtu.be/gxT8TfI5DaE

lo_zamoyski• 1 year ago

Mechanical computers are a great reminder of what computation is and what it isn't.

Computation as studied by computer science is not a physical phenomenon, but a mathematical construct that claims to formalize the notion of an effective method. This claim is perhaps most tangibly expressed in the form of the Church-Turing thesis.

Computing devices are not objectively computing. They simulate the formal construct. Anything that can be used "computer-wise" can be said to be a computer in the same manner that anything that can be used chair-wise can be said to be a chair. But there is nothing inherently computational about the device itself.

Joker_vD• 1 year ago

Computing devices are not objectively computing. They simulate the formal construct.

Isn't it backwards? I don't think that e.g. herding sheep into the pen while making a mark on the door for each sheep "simulates counting sheep". Instead, you can use the formal construct "counting sheep" to describe this physical process: "doing this and this will count the sheep".

Otherwise you may very easily end up puzzled why maths is so unreasonably effective in natural sciences.

I Built a Mechanical Calculator [video]

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