gcode_preprocessor.py¶

CLI: scripts/gcode_preprocessor.py, code in triaina/preprocess.py (also used by the service). Standard library only; Python 3.9 or newer.

python3 scripts/gcode_preprocessor.py INPUT [-o OUTPUT] [options]

Options¶

Option	Default	Meaning
`-o, --output PATH`	`INPUT` with `.cut.gcode` suffix	Output file. `-` writes to stdout
`--max-feed MM_MIN`	`1500`	Every `F` word is capped at this
`--default-feed MM_MIN`	`1500`	`F` added to the first XY move if the job never sets one
`--z-threshold MM`	`0.0`	Z at or below this means "cutting"
`--no-wrap`	off	Omit the `CUTTER_MODE` header and `PRINTER_MODE` footer
`--home`	off	Emit `G28` before `CUTTER_MODE`

Exit codes: 0 success, 1 cannot read input or write output, 2 bad arguments.

What it changes¶

Input	Output	Why
`M3`, `M4` (spindle / laser on)	`CUT_PLUNGE`	LightBurn and laser posts signal "tool on" this way
`M5` (spindle / laser off)	`CUT_RETRACT`
`G0/G1 Z<=threshold`	`CUT_PLUNGE`, Z word removed	Real cut depth comes from `z_cut` on the printer
`G0/G1 Z>threshold`	`CUT_RETRACT`, Z word removed
`T<n>` (tool change)	`CUT_RETRACT`	Lift before any pause; Klipper has no tool table by default
`E` words	removed	No extruder in cutter mode
`M82 M83 M104 M106 M107 M109 M140 M190 G10 G11`	removed	Heaters, fans, extruder mode, firmware retract
`F` above `--max-feed`	clamped
`N` line numbers, `*` checksums	removed	Meaningless after rewriting
Comments, macro lines, other G/M codes	kept

Plunge and retract are only emitted on a change of blade state, so a multi-pass job that steps from Z-0.1 to Z-0.2 keeps the blade down and does not emit a second plunge.

Relative Z (G91) is tracked. If a file starts in G91 with no known Z, the sign of the move decides.

Output layout¶

; processed by triaina gcode_preprocessor
; removed: E x120, M104 x1
G21
G90
CUTTER_MODE
CUT_RETRACT
... body ...
CUT_RETRACT      ; only if the job left the blade down
PRINTER_MODE

Python API¶

from triaina.preprocess import Options, process_lines

out = process_lines(open("job.gcode").read().splitlines(), Options(max_feed=1200))

process_lines is pure (no I/O) and returns lines without newlines. classify_z_move(new_z, z_threshold, blade_down) returns "CUT_PLUNGE", "CUT_RETRACT" or None.