The Turbo Entabulator: A 3D-printed Mechanical Computer

An anonymous reader writes "Have you ever been sitting there, quietly computing something and thinking to yourself, 'If only this process were somehow billions of times slower, less reliable, and involved lots of physical labor?' If so, the Turbo Entabulator is the machine you've been looking for! It's a (nearly-entirely) 3D-printed mechanical computer. With three single-digit counters for memory, it's driven by a hand-cranked, Jacquard-style punch card reader. You can even download the files and build your own."

Good for teaching ...

[gstoddart]

So nobody is likely to use this for actual work, but as a teaching aid, it definitely goes a long way. Explaining with a working physical device the principles of basic computing and Turing machine type things is pretty cool

And, if someone has done this, it's only a matter of time before we start getting some super awesome 3d printed Rube Goldberg type or Steampunk-type of devices.

Re:Good for teaching ...

[plover]

I was amused that he built it because his 3D printed Jacquard Loom was even less reliable.

3D plastic extrusion printing is fine for printing a pencil cup or a replacement game token, but a precision manufacturing process it is not. There's a reason machined parts have tight tolerances: without them, moving parts bind, jam, and break.

Mechanical calculators

[Clueless Moron]

I have one from around 1958, and it's quite satisfying to use. [photobucket.com]

They can multiply and divide as well as adding/subtracting. The above link shows the result of doing 355/113: 3.1415929 with a remainder of 23.

The top left is an accumulator, the top right is a counter, and the lower register is the number you want to add/subtract (entry register). So to do 355/113, the procedure is

1. Pull all three 3 metal tabs on the sides to clear all registers
2. Enter 355, press the rightmost red arrow button to shoot the entry register number all the way to the left
3. Crank forward once. You now have 3550000000000 in the accumulator and "1" in the counter's leftmost position.
4. Squeeze the two rightmost chrome handles together to clear both the counter and entry register back to 0
5. Enter 113, press the rightmost red arrow button to shoot the number all the way to the left. You're done entering numbers at this point.
6. Crank backwards to subtract from the accumulator until it is less than the entry register (takes three times). Don't worry if you overshoot; a bell will ring to indicate underflow and you just add it back. The counter now shows three in the leftmost position. The red dot indicates that it notes you started off subtracting, so it's counting backward cranks as +1 instead of -1.
7. Press the right arrow to shift the entry register one position to the right
8. Repeat the subtracting process, shifting right until you can't go any more right. You're done.

It sounds more complicated than it is, but really it's just long division. It takes about 20-30 seconds to do that division. That sucker works as well as the day it was built. I've looked inside; it's a mechanical marvel.

Oh yeah, those white slider tabs are for placing the decimal points where you want them