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Openbuilds GRBL PostProcessor

Why?

The built-in 'GRBL Generic' post-processor that comes with Autodesk Fusion360 has a number of problems. Looking into the code (these post-processors are written in JavaScript) I realised it was more a quick & dirty hack.. After finding a nice Class Reference I decided to give it a try and write a better GRBL Post Processor

Assumptions :

1. Functional restrictions of GRBL - currently version V0.9j

• 1.1 only 3 axis - so don't bother with 5-axis functions - When these functions are called, an alert is raised
• 1.2 no automatic tool change - no need to send tool-change commands - Post-Processor should warn if multiple tools are used in 1 NC file
• 1.3 radius compensation is not supported, so raise an alert when used
• 1.4 see: https://camforum.autodesk.com/index.php?topic=7571 / https://github.com/vlachoudis/bCNC/issues/88#issuecomment-129568125 . This issue needs further investigation - could be solved with more digits..
• 1.5 GRBL does not support 'Canned Cycles'.

2. Based upon making things simpler and thus more solid

• 2.1 don't try to save a few characters on blocks that only appear once per section - do a proper initialisation at each section start
• 2.2 always send comments. They will be ignored by GRBL, only appear at file/section begin and make the GCODE more readible
• 2.3 don't use linenumbers : GRBL doesn't use them, and when editing each editor has them anyway, so why have them in the GCODE...
• 2.4 don't remove spaces... UGCS can do this for you before sending it to GRBL
• 2.5 don't use G28 to return to home. Use G53