Back again. Implementing CNC-like controls

EverythingOpen conference presentation done, back to project work. I'm implementing CNC-like controls to home the axes and set the zero positions for XY and Z to allow CNC-like control.

This is not a straightforward as it seems. I can't just tell the GRBL to home because the XYZ on the GRBL does not correspond to the XYZ of the stage. So to do a HOME I have to first position the stage XY to zero, then move stage Z to zero. This stops me dragging the probe over the stage, and I think that bit works.

Setting new zero positions for XY and Z before beginning "work" has a similar problem, so I have to design a relative zero for all axes and factor that in for all move commands. Haven't done that yet.

Finally, I'll want to read in a gcode file and move the stage around. Again, this requires translating stage positions into relative positions, then moving the towers with GRBL. I'll experiment with using jscut http://jscut.org to generate the gcode from SVG files. I'll probably have to implement some kind of scaling system for the gcode because I'm not sure how jscut will handle very tiny numbers (Inkscape certainly fails on this).