About construction set
The main join element is screw M4 or plastic pin. Construction set has been actively developed since 2011 and it contains more than 300 different pieces, named as beams. You can create your own pieces and open source library for OpenSCAD can helps you with that.
Construction set is distributed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license. Authors want to share their hard work on that, so any 3D Printer owner can print any piece with any colour for free. But for next project financing some material might be charged.
Specification
Basic unit is beam in size 8 mm x 8 mm x 8 mm. If beam has a hole, diameter of hole is 4.8 mm. Basic element to join beams to each other is screw M4, which has been replaced to 3D printed pin. Pins look like as little bit wider fork, so they holds in the holes much firmly. But it depends on used printing material, so it might be a challenge print it right.
- beam size 8 mm
- half size beam 4 mm
- hole diameter 4.8 mm
- shaft size ⌀ 4.3 mm x 3.7 mm
- shaft hole ⌀ 4.5 mm x 3.8 mm
- gear wheel width 3.8 mm
3D printing
Most of pieces is best to print from PLA or similar materials. It can be also printed from PET, but pieces are more flexible. Layer height 0.2 mm is good enough. Print with higher layer might not look so good, but it should work fine (it depends on printer and printing parameters). But mostly it is possible to print with higher layer.
Pins and shafts are printed from PET and similar materials. Both of them have to be print in landscape, to better adhesion to print sheet. For better precision in height (that means width) pins and shafts (3.7 mm), we suggest to print with 0.2 mm layer height, and use Height range Modifier in Slicer from 1.8 mm to 1.9 mm with layer height 0.1 mm.
Some specific pieces (wheels or rolls) are printed from more flexible material (TPU). When you will print from TPU, don't forget, that material have different mechanical parameters. Pins can fit more loosely, or might be harder to round it around shafts.