Which post processor do I use for an OpenBuilds machine with a BlackBox controller?

What to select

OpenBuilds publishes its own post for this software, written for OpenBuilds machines running Grbl 1.1. It comes in two versions, and these are the names you will see in the list:

• OpenBuilds GRBL (mm) (*.GCODE)
• OpenBuilds GRBL (Inches) (*.GCODE)

Both save a file with the .GCODE extension. The post files themselves are kept in OpenBuilds' public repository, and their change history shows they were adapted from the standard Grbl post with help from the software maker.

Steps

1. Open Machine > Machine Configuration and use Search Machine Online to look for OpenBuilds. If found, download it and the posts are attached for you.
2. If you cannot find it, open Post-Processor Management from the Machine menu and look for the two OpenBuilds GRBL entries. Add the one you want under Associated Post-Processors.
3. As a last resort, get the .pp files from the OpenBuilds repository and use the Install Post-Processor icon.
4. Save the toolpath and open the .GCODE file in your sender to run it.

What the post does (useful to know before the first run)

• The file starts by setting the units (the mm version sends G21) and absolute positioning, then moves to the Home / Start Position from Material Setup. Make sure that position is sensible for your machine.
• Spindle start is followed by a short dwell of 1.8 seconds so the spindle can come up to speed before cutting.
• Arcs are output as true arc moves. The change log shows very small arcs are converted to straight moves through a minimum arc radius setting (1 in the mm version, 0.04 in the inch version), which avoids arc errors on tiny curves.
• The header was updated in 2020 specifically for the BlackBox.

Tool changes

The post is not an ATC post. Save one file per bit and zero Z after each change.

Pro tips

• Use the mm version unless your whole workflow is in inches. GRBL boards are metric by nature.
• If you run a laser, check that your copy of the post is current through Update Post-Processor List, since laser output was added in a later revision of the Grbl post it is based on.
• See the entry on GRBL hobby machines for the general rules of this controller family.