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The 3D-Printed Curta Calculator


The 3D-Printed Curta Calculator

Adam walks us through his collection of analog calculators, culminating in one of his newest favorite objects: a 3D-printed Curta calculator that's a perfect scaled reproduction of the intricate mechanical computer. This incredible replica was engineered and built by Marcus Wu, who started the project two years ago.

Read about Marcus' journey to design and build this 3D printed Curta calculator here:

Shot by Gunther Kirsch and edited by Norman Chan

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Tested is:
Adam Savage
Norman Chan
Simone Giertz
Joey Fameli
Kishore Hari
Frank Ippolito
Sean Charlesworth
Jeremy Williams
Gunther Kirsch
Ryan Kiser

Thanks for watching!


3D Printed Curta Calculator Assembly

Assembly of a 3D printed Curta Calculator.

Parts, Bill of Materials (including tools and non-printed parts), and Build manual located at

Build progress blog at

How the CURTA Works

The CURTA calculator is a marvel of engineering and a favorite of collectors. This video describes in detail how the CURTA Type I calculator works. (The operating principles of all the CURTA models are the same as for the Type I.) This video was created using the YACS CURTA simulator, which you can play with at

CURTA Calculator Assembly

Zusammenbau einer Curta Rechenmaschine
Demonstration of CURTA calculator assembly
CURTA was manufactured from 1949 to 1971 at Contina AG in Mauren, Liechtenstein
CURTA history is displayed in the museum MuseumMura, 9493 Mauren, Liechtenstein

3D Printing and Testing the Makerbot Coin Sorter

We have lots of coins at the house, so I thought it was time I 3d printed a coin sorter. I found one on Thingiverse, and printed it twice. Once on the Ultimaker 3 using Colorfabb HT, and once on the Lulzbot TAZ6 using Polymaker Polylite PLA.

#3dprinting #coinsorter #highfive

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CURTA Mechanical Calculator Demonstration

How to do addition, multiplication, subtraction and division using a Curta Mechanical Calculator.

Plus 1 Minus 1 on a 3D Printed Curta Calculator

Adding and then subtracting 1 on a 3D Printed Curta Calculator to return to zero. Subtraction is one of the most difficult operations for the 3D printed calculator to get right as it does subtraction through addition. Subtracting the same value just added to return to zero requires every digit of the calculator to be operating flawlessly. Each digit must rotate all the way through 9 while carry cascades through all digits sending them back to zero.

More details on the project at
3D Print files are available at

Home Shop Curta Calculator Episode 1

Join me as I venture down a road less traveled and begin to build a Curta mechanical calculator in a home machine shop. The Curta is a device of mechanical marvel - over 100 unique part numbers and over 600 parts make up just one Curta. The Curta can add, subtract, multiply and divide with a hand crank!!!

This video is the beginning video in a vlog / montage style journey. Tooling needs to be manufactured. CAD models need to be constructed. G code needs to be created. A story needs to be told. The Curta's brilliance emerged out of the ashes of World War II, quickly eclipsed by the electronics revolution. But that revolution only hid the brilliance of the Curta and it's development story. So let's retell the story from a machinist's perspective!

In this video I start by making up some chuck backplates for the rotary table. The backplates were manufacturing out of older cast iron lifting weights and machined up very well.

Follow me on Instagram or Twitter for almost daily updates and stay tuned for further announcements on how you can directly support and get involved with this project. #curtabythecogwheel

Music for the video was created by Philter and was used with permission. Many thanks to Magnus for allowing me to use this music. Check out Philter Songs used were from albums Queen of Crows (Miyazaki Mountain) and The Classic Tapes (The Lounge and Bathtime in Heaven). Also thanks to @The Joy of Precision for letting me know about Philter!

If you want access to the original drawings you can find them here:

Show and Tell: The Curta Calculator

Sean Charlesworth joins us in the Tested office this week to share one of his prized possessions: a Curta mechanical calculator. Designed in the 1940s before electronic calculators, this hand-cranked device was considered the the most precise pocket calculator available, and was used by rally car drivers and aviators.

Learn more about the Curta Calculator here:

The Amazing Story of the Curta Calculator


Re-upload from 6 months ago due to content issues. Enjoy!

Telling someone 100 years ago that we all have powerful calculators in devices in our pockets today would've absolutely blown their mind. Back then, calculators were large mechanical devices that sat on desktops and were used by the technical elite. The common person would have nearly no way to access a calculator of any means, nonetheless a portable one.

However, in the mid-1930s, a man named Curt Herzstark had an idea that changed the world of calculators forever. He worked as a mechanical calculator salesman in the former Austrian Empire and consistently heard customers complain about how bulky these mechanical monoliths were. They were expensive and just too large to be practical in many applications. Many even desired something completely new: a calculator that could fit in a pocket.

For 10 years, Curt worked on a mechanical calculator concept that would drastically reduce their size and allow him to create a device that perfectly met the needs of the market.

All images and videos courtesy of the creative commons or used in accordance with fair use. For any comments or inquiries about use, please see the contact section on our channel page.

Namaste by Audionautix is licensed under a Creative Commons Attribution license (

3D Printed Curta Demo revisited

The original 3D Printed Curta video did not yet have the results dials painted. These are now painted and this demo shows that the Curta does work as designed.

Functioning 3D Printed Curta Mechanical Calculator

After a year and four months of planning, modeling, printing, and assembly I now have a functional Curta.

I still need to paint it and add in numbering and lettering to be able to read the results.

3D print files are now available at

Curta Calculator Unboxing

Adam Savage commissioned a 3D Printed Curta Calculator from me. We worked out a trade of a Curta for a Curta. He unboxed his in this video: Here I am excited to unbox the one he sent me -- a Curta Type II!

3D Printed Curta Demo

Demonstrating functionality in my 3D printed Curta Calculator. I perform a simple addition and subtraction of two. Unfortunately there are no numbers on the results dials so the result cannot be seen, but the rotation of the dials can be seen.

Blog post on the build progress:

3D print files available at

3:1 3D printed Curta Calculator test trice

Not finished, but it adds!

The 3D Printed Curta Calculator

3D printed Curta model, a pocket mechanical calculator, Part 1

This is part 1 of the 3d printed Curta building process.
The Curta itself is a wonderful and elegant device. This 3:1 fully functional model is based on the original Curta type I is, even more, a masterpiece.

All credits of the model go to Marcus Wu, for his wonderful design.
See the for the original video from Marcus Wu

3D Timelapse: Curta Calculator - Upper Housing (Part 1/250)

Tech Icons: Cliff Stoll - The Curta Calculator

To see more interviews with Tech Icons, visit

The legendary Cliff Stoll tells the story of the invention of the Curta Calculator

Curta Calculator/Curta Calculator Design, How To Use and How It Works (Curta Calculator Animation)

This beautiful educational video will tell you all about Curta Calculator. Here you will know, what is Curta Calculator, Curta Calculator design, the working of Curta Calculator and how to use Curta Calculator. So this is a very useful curta calculator animation to clear all your concepts about Curta Calculator.

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