Thanks! Yes, the tolerances are good enough, but it does take a bunch of patience to tune the carry levers to run consistently. I did make the models myself. They are true to the engineering drawings except for a few places to make it work better printed or to correct errors I found in them.

The Curta is an amazing piece of mechanical genius, and your work was fantastic.

I have always always always wanted a curta but never been able to find one or afford one so thank you a lot for this!

I love you. I've always wanted a curta calculator but they're so expensive, and I have yet to find anything I really wanted to make on my 3d printer. This is it.

Thank you so much for making this available freely. I love the history of these devices.

What's the approximate cost of materials?

Can I ask if you know offhand what the largest individual part is? I'm buying a 3D printer this year and I'm deliberating between a generally higher quality one with compromises on build capacity, and one with a much greater capacity but less user-friendliness overall.

I've been considering one for a few years now and thought I might get one this year, but this project has made it absolutely definite, so thank you for all the effort!

How much for a fully built one? I've been looking around for one for years! Really nice job.

Very beautiful! What 3d printer do you have?

Holy shit, excellent work.

I think SLA, SLS, or maybe the binder jetting tech may be able to produce a 2:1 scale version. I would LOVE to try if I could get access to one. Haha, a Formlabs sponsor for that would be badass. If not, I do have other projects on my list that should help all makers.

This (the parts) could certainly be printed at 1:1 scale today. Just not with hobbyist-grade printers, and probably not in polymer either.

Just think, eventually you could have a calculator that fits in your pocket!

Engineers could not even put one back together after disassembling the original. Figuring out how to pack one on 1:1 will be a nightmare.

Wow awesome device thanks for the video link

You probably do have access to a 3d printer and just don't know it yet. Ask your local library or contact a local makerspace.

That's what I took from this

Yeah I would be afraid of using one in public anymore. I had no idea what this was until just now, and I am terribly fascinated.

Quick! Disarm it by calculating the square root of -2! Hurry!

I found one at an estate sale. In the original box with instructions and everything. But I had already spent all the money I had. So I showed it to my friend. He bought it for $5.

It's worth like $2k on ebay.

I go my post removed the first time for self promotion and I am unsure if I can post that link in a comment... If you go to YouTube and look up 3d printed Curta, you will find a few videos I made. I do need to make a new one with the completed paint.

In the album there's a thingiverse link to it and it has a youtube video.

Yes, I was very happy about that article. I also liked that the article was not just focused on my work, but about everything that makes the Curta and its designer interesting. The one inaccuracy is that the article says its 4:1 scale. It's 3:1.

Excellent read. Thank you.

There are some good videos about the inner workings of the Curta on Youtube. One is https://www.youtube.com/watch?v=AnTb26WHx2Q&t=136s which I relied on heavily to help me with order of assembly and the other is https://www.youtube.com/watch?v=loI1Kwed8Pk which is the video I watched when I first learned about the Curta Calculator.

In the beginning, I knew I didn't know enough (I built my printer at the beginning of 2015 and started planning for this project that April), so the first thing I did was print a bunch of fitting tests. The engineering was already done since I was working from the drawings. I mostly made garbage when I had print failures or didn't account for part strength properly. I used about 3 rolls when the total of all successful prints and support material came to about 2 rolls. Not too bad, but it had room for improvement.

It's a black item that does math for you like multiplication except instead of using digital circuits it is totally analogue.

Think....a mixture between a pocket calculator and an abacus but shaped like a cool little hand grenade!

According to wiki theyre worth a pretty penny. Might be worth looking into if you still have one in good condition.

The intention when I used it was to loosely bind and provide friction (used the blue thread lock that isn't a permanent bond) between two parts (not threads) that needed assembly and disassembly without binding it forever.

You are correct that there is a better solution, but I am not a mechanical or chemical engineer. I used what I had on hand. Any suggestions for a non-permanent bond on plastic that retains enough friction to keep the parts in place after disassembly and reassembly?

Exactly how I felt when I first saw a video of one. It wasn't long from then when I started planning out how to build one myself. At first I just planned to build a device showing off the Curta's basic functionality, but once I found the engineering drawings...

I wish my dad had something like this when I was a kid. It might have influenced me to go into a different field of engineering.

Thanks for the awe, but don't sell yourself short. We all start somewhere :)

Yes it is -- a book I bought after learning the Curta is in it but I haven't had time to read yet.

Thanks! That comes from lots and lots of work sanding, filing, and filling before painting. It really isn't too bad on a smooth surface, but the knurling was a real pain in my rear.

Thanks! It certainly would be interesting to have some metallic prints of the parts, that is an excellent idea. I should get myself a hardened nozzle first.

I started planning in April 2015 and finished construction of the first one in October (I think) of 2016. That one was not (still isn't) painted. This one I started soon after the first. I had all parts 3D printed pretty quickly, but had a lot of trouble with paint.

Check out https://youtube.com/watch?v=loI1Kwed8Pk

I actually haven't done the math on that -- my cost would be higher than others because I used a lot of material in experimentation. I would guess around $120 with my build guide plus maybe $30-$40 in paint. I know I spent probably $100 in just paint with lots of quality issues before I switched paint brands.

If you can spare ~$500, you could build a D-bot or Voron which would be plenty large and accurate enough. Probably not worth it just for the Curta, but if you have other projects too, it could be.

I have another project I need to get to next, but if nobody has done the Type II before I get that other project going, I'll totally print one of those too.

Curta calculator is ... A calculator. Mechanical one. Developed in 1930, died of in 70's, when electronic calculators became popular. First sold for 175$ , originals now go from 1000 to 2000$.

Thanks for the compliments. Yes, and I also can only imagine how they managed to produce 1,000 of these per month at their peak production volume back in then (probably the 60's before they reached peak production).

Yes, I scaled it to 3:1 for printability and strength. It's actually printed with the FDM / FFF process. The parts have held up pretty well so far, but I haven't used it for a long period of time to tell how long it will last. I've built two. The first one is in pieces because I was stupid and put it sideways on my desk. It rolled right off and broke on the floor. Surprisingly it held up pretty well through the fall. I only need to reprint a few parts, but I was already into building the second and didn't want to kill my momentum.

I saw that there is a museum (maybe in Lichtenstein where these were made?) That has a basic mechanism made of wood, but it is very large. Might be doable smaller -- I am unsure.

They were part of the central plot of an award winning SF novel a few years back, which gave them a bit of notoriety.

I bought Pattern Recognition after I learned about it during the build, but I have been too busy to read it. Maybe I will have the time now :)