OpenSCAD Hirth Joints

https://github.com/mechadense/scad-lib-hirthjoints

Author: Lukas M. Süss aka mechadense
License: LGPL-3.0
Description: A minimal function for generation of hirth joints.

This is more meant as a library.
Deliberately kept minimal.

Customizer (on thingiverse - TODO needs debugging)
is just meant as a quick preview of what can be done.

Note that there is no math for sanity checking of supplied parameters.

Usage tipps:

use hirth ( n = 12 , r = 24 , zbase = 8 , slant = 60 , a1up = 10 , a1down = 12 , cuttype = "cylindrical" , dbore = 12 , acone = 0 )

• Always keep down_angle bigger than up_angle or the roofs will hit the valleys.
• If you use ist as a cutter then increase r and decrease dbore compared to the counterpart such that the teeth will fit radially.
• For printing a hirth interface at the bottom of a FFF-3D-print one can avert the need for support material by cutting off half of the teeth. This still meshes with full teeth but not with cutoff teeth.

Notes:

This is the third and so far most performant attempt.
It uses convex hulls to span volumes.

I found that the crux for Hirth joints is to 
*operate in spherical rather than in cylindrical coordinates*

The generated joints are geometrically correct.
Just as these ones I recently found are:
https://www.printables.com/model/114737-hirth-joint-with-source-files-and-documentation
Same for preceding ones listed below.

TODO – I will update the links to printables links once those are migrated too.

History of preceding attempts:

Elegant but inefficient & buggy (attempt two):
Intersections of approximated halfspaces
– https://www.printables.com/model/430631-customizable-hirth-joint-csg-version-library-depre
– https://www.thingiverse.com/thing:397553

Earliest (attempt one):
Vertices and meshing: https://www.thingiverse.com/thing:387292

Category: Robotics