Sep 1, 2016 | By Tess

Before the electric calculator was invented in the 1970s, a pocket-sized mechanical device called the Curta was one of the best options for calculating simple mathematical equations. The device, which consists of a small barrel with number sliders and a revolution counter that can add, subtract, divide, or multiply numbers, was invented in 1938 by Austrian inventor Curt Herzstark. While many of us may never have (and probably never will) use a Curta, one software developer’s interest was piqued by the device and he set about making his very own functioning 3D printed Curta.

The maker in question, one Marcus Wu, took up the 3D printed Curta project over a year ago and, despite much doubt surrounding the project by observers, he has finally completed a working 3:1 scale model of it! The calculator device, which Wu painstakingly designed using Onshape, was based on the original device’s engineering drawings and printed on a gMax 1.5 3D printer. Fortunately, Wu detailed his whole process on his blog, so we can see for ourselves exactly how he achieved such an incredible 3D printing feat.

What becomes very apparent through the blog is that making the Curta was anything but an easy task, as the maker faced a number of challenges in all steps of the process. From turning the engineering drawings into 3D printable parts, to making sure the parts would be durable enough to function, to breaking many 3D printed parts, and to overcoming a number of precision-related issues, the journey was full of ups and downs. Finally though, after a long 18 months and much patience and perseverance, Wu has successfully assembled and tested his own Curta, which weighs about 3 lbs is made up of roughly 240 3D printed parts and 100 unprinted parts such as screws, springs, and ball bearings.

Now that Wu has succeeded in creating a functional 3D printed version of the Curta calculator, the next and final steps of his project will include numbering the sliders on the device—which will inevitably help with the math part—and painting and finalizing the calculator’s decorations. For this last step, Wu has already gotten a head start designing his Curta’s logo (inspired by the original engineerings drawings) and is looking for tips on how best to paint the device without affecting its functions.

If you’re inspired by Wu’s hard work and 3D printing skills, you’ll be happy to hear that the dedicated maker is planning on making his designs and 3D printing files open-source, so that anyone up to the challenge can make their own Curta calculator. This may take some time, however, as Wu stated that he wants to double check his files and write up a comprehensive tutorial for future use. If you want to see the Curta calculator in person, Wu will be presenting it at the Charlotte Mini Maker Faire on October 8th at Charlotte, NC's Discovery Place. For those who simply want to see the 3D printed calculator device in action, check out the video below:



Posted in 3D Printing Application



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Joe D wrote at 9/8/2016 4:03:45 PM:

Of course, we are yearning to see the mechanism inside working. I know that 3D printed transparent material is not really see-through. But, I wonder if a laser cut polycarbonate cylinder can be used for the outer housing. Then, the interior parts colored to make them stand out more as they move.

g wrote at 9/2/2016 2:00:24 AM:

Awesome work! Happy it was on a gMax too.

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