GRBL Router post
At a glance
- Z-aware linear and helical G2/G3 moves for contour, bore, and chamfer
- Adaptive pockets replay the full move stream with planar links and separate Z lifts
- Explicit Z peck and retract moves for drill operations
The bundled GRBL Router post targets GRBL-based routers and hobby CNC machines. Select it on your
machine profile's Post tab and it becomes the machine's post for
every job. The program opens with absolute mode, G20 or G21 to match the machine's units, the
XY plane, feed-per-minute mode, and your chosen work offset; the spindle starts with M3 S using
each operation's tool RPM and stops with M5 at the end of the cut.
What it emits
Contour, bore, and chamfer paths post as Z-aware G1 linear moves and G2/G3 arcs — imported
arc geometry is never flattened into chords, and Bore's helical entries post as true helical arcs.
Adaptive pockets replay the generated move stream exactly: linking moves stay planar at their link
height, Z lifts and plunges are separate commands, and the dynamic lead-in/lead-out arcs post as
G2/G3 rather than sampled segments. Drill operations write their peck and retract cycles as
explicit G0/G1 Z moves, since GRBL has no canned drilling cycles.
Options
Post options live with the machine profile: work offset (G54–G59), a fallback spindle RPM for
operations without one, safe retract height, arc output as I/J center offsets or R radius
words, word spacing, and the output file extension (gcode by default). Like every JetCad3 post
it's a plain-text .jcpst file — Edit Post… on the Post Process dropdown opens the source if
you need to tweak the dialect.
Streaming with GcodePilot
This post is tagged for GcodePilot, JetCad3's built-in sender, so the Post button reads Post to Machine: generate, post, and stream over a USB serial connection without leaving the app. See post to machine for the full workflow.