waterline + pocketing. Can it be done?

[koppi]

Two days ago I came across http://touch-mapper.org/

It exports STL files from OpenStreetMap data. This allows for creating a tactile map for blind people.

Because I do not have a 3D printer, only a small CNC mill and there's no good CAM software available on Linux, I decided to give a try to opencamlib and wrote an STL to G-Code converter wrapper, see:

Demo: https://github.com/koppi/stl2ngc/wiki Video: https://www.youtube.com/watch?v=ldCAnd6YzOU
and Code: https://github.com/koppi/stl2ngc/blob/master/stl2ngc.cpp

One problem with stl2ngc.cpp is: the zigzag algorithm works, but the G-Code job time is quite too big. I would like to have a mix of the waterline and pocketing algorithms, but I do not know, howto put this idea into code.

@aewallin Can you give me any advice?

[aewallin]

I didn't work on combined algorithms yet.

I think you could run the waterline algorithm at a certain depth, or perhaps multiple depths, and if you find deep "holes" you can identify these as good candidates for waterline-pocketing (instead of zigzag machining).
I didn't make a pocketing algorithm yet. A zigzag algorithm for pocket could be fairly simple to make, but with many islands or holes it gets tricky to optimize the number of lift-offs you have to do. Another option is offset pocketing using openvoronoi or clipper or another library. Again you have to link the offsets together somehow.

I don't have much time to work on CAM algorithms unfortunately....

[ksuprynowicz]

Hi!
@koppi
You can try using opencamlib with BlenderCAM:

https://github.com/vilemnovak/blendercam
https://github.com/vilemnovak/blendercam/wiki/Using-BlenderCAM-with-OpenCAMLib

You can import STL to Blender, generate waterlines with opencamlib using BlenderCAM GUI, and create pockets from them with BlenderCAM. No programming needed at all :)

@aewallin And thanks for the awesome CAM library. Without it BlenderCAM relied on Bulletphysics, so drop cutter sampling and waterline quality was not good enough to use in commercial setting.

Here's a version that works with VTK6(ugly fix) and has some memory leak fixes in waterline algorithm (found with Valgrind):

https://github.com/ksuprynowicz/opencamlib