This tool is the addition-only version of the mechanical calculator. Or as commonly known, the Addiator.

Need to add some numbers?

But if you find yourself without your mobile phone, computer, calculator, smartwatch, or a spare scrap of paper and a pen, this is the tool for you! Now you can add numbers like the cool people did in the olden days. I believe these came out around 1920, so over 100 years ago.

I found this device when deep in a YouTube session and was keen to see it working.

I have also designed two other versions of this, both of which will also do subtraction. However, this one is the smallest and quickest to print if you just want to see how it works.

Printing

This print was created for multi-colour printing with an AMS, so you can modify the colours as needed.

If you are importing the STL files individually, load all the files starting with TOP, which will then group correctly.

Repeat the same for the SLIDE.

I've included a single colour, pre-combined, SLIDE and TOP if you are just printing one colour.

The Bottom and stylus are single colour only.

How to Use

It seems a little complicated to start, but once you start using it and learn the rules, you can very quickly start doing large additions.

Reset the device by tilting it forward until the numbers all read ‘0’.

Insert the stylus into the slots next to the number you want to add and drag it to the bottom.

If the slot has an ‘Up-Arrow’, slide it up to the very top instead, then over to the left and then down.

If you then see a ‘+’, insert the stylus into the ‘0’ position and again move it up, over, and down.