Soroban - Fully Parametric & Configurable Abacus

I recently watched a video of Japanese school kids using their Soroban to calculate at incredible speed; apparently it also helps with learning to do very fast mental calculation. I was impressed, and wanted to try and learn that – after designing and printing my own Soroban, naturally 🤪

I designed this Soroban in FreeCAD (Link branch version 2023.01.31).

The model is fully configurable and you can easily change the number of rods/digits, beads, and most dimensions by editing the spreadsheet values inside the CAD file.
That also means you can change it to a traditional Soroban with five earthly beads, or a Chinese type Suanpan with two heavenly beads. Or even a hexadecimal programmer's soroban!

I don't own a standard Soroban, so I don't know if the dimensions are correct/typical. If you do, please comment so I can improve it!

To change the parameters:

1. Download the FreeCAD file (.FCStd)
2. Open it with FreeCAD Link branch (you can get it here: FreeCAD Link Branch)
3. Double-click the “parameters” spreadsheet icon in the model tree on the left
4. Edit the spreadsheet values – The model will update automatically!
5. Select the parts/bodies in the model tree and do File → Export (or Ctrl+E) and save as .stl
   ("frame", “innerframe”, “bead”, one after the other)

FreeCAD will automatically recompute the model each time you change a spreadsheet value. This can be slow – you can right-click the “soroban”-document in the model tree and select “Skip recomputes”. When you're done editing the values, re-enable, or click the recompute button (F5).

Assembly:

1. Cut your rods to the required length (≈75mm for the STLs I uploaded). I used pieces of 2.85mm filament.
2. Thread the beads onto the rods.
3. Place/snap the rods into the frame.
4. Snap the inner frame into the outer frame. This may need a bit of force.
5. Put the indicator dots into the small holes. I used pieces of 1.75mm filament.

There are plenty of tutorials for learning Soroban calculation on youtube and elsewhere.

When you make one, let me know!
Enjoy!