Curt Herzstark had been working on the calculator in the 1930s until the Nazis forced him to focus on building other tools for the German army. He was taken by the Nazis in 1943 and ended up in Buchenwald concentration camp. There, he told the officers about his plans for the CURTA. They were impressed and interested enough to let him continue work on it so they could present it as a gift to the Führer. The CURTA mechanical calculator literally saved its inventor’s life. / The CURTA Calculator Page

3D printed version by Marcus Wu

Curta Calculator Type I scaled at 3:1

• github (scale 3x) / Printables / thingiverse
• onshape 3D (scale 1x)

Some facts:

• There are around 240 printed parts – around 100 unique parts.
• There are about 100 non-printed parts (ball bearings, springs, screws, nuts, etc)
• The original Curta had over 600 parts.

I combined many of them for simplicity when 3D printing. It weighed 1357g (just about 3 lbs) before painting. I used around 2 spools on the successful prints, but it was 3 spools counting failures. I first started researching for this project in April 2015. I had my first functional Curta in the Fall of 2016. This is the second Curta I’ve built and the first one I’ve painted. CAD work was done from the original engineering drawings in OnShape.

Functionning

Assembly

• Instructables

see also

• Calculation before we went digital
  • Evolution of the Calculator 2,000 BCE - 2020
  • Mechanical Computer (All Parts) - Basic Mechanisms In Fire Control Computers
• How the CURTA Works - describe mechanical principle behind operation - (Leibniz Stepped reckoner) - with one common cylinder
  • Pocket Mechanical Calculator - Addiator/Addifix
• CURTA Calculator Assembly
  • This Amazing 70 Year Old Calculating Machine