Cutting a design file

The dashboard turns a design file into cut G-code on the Pi: no Kiri:Moto, Inkcut or Inkscape export needed. Choose Cut design as the job type and drop the file.

Formats

Format	Read with	Notes
SVG	svgelements	Units, viewBox and transforms honoured. Text must be converted to paths (Inkscape: Path > Object to Path); text elements are skipped with a warning
DXF	ezdxf	Lines, polylines, arcs, circles, splines, ellipses, blocks. $INSUNITS sets the scale; unitless is read as mm. Text is skipped
PDF	pdftocairo (poppler-utils)	First page only. Text is converted to outlines automatically
AI	pdftocairo	Only PDF-compatible files ("Create PDF Compatible File" in Illustrator)
EPS	ghostscript, then as PDF
PNG, JPG	Pillow + potrace	Black-on-white logos trace well; photos do not. Width is required (or shrink to fit): pixels have no real size

setup_pi.sh --service installs the three programs. A missing one makes only its format fail, with the apt install line in the error.

Options

Option	Default	Meaning
Width	the file's own size	Final width in mm; height follows the aspect ratio. Required for PNG/JPG
Shrink to fit	off	Scale down to the bed if the design is larger. A design is never shrunk silently: without this, too big is an error
Weeding border	0 (none)	Rectangle this many mm around the design, for peeling the waste
Blade offset	[cut] blade_offset (0.25)	Tip offset of your blade; 0 disables compensation
Image threshold	128	PNG/JPG: pixels darker than this are the design
Light on dark	off	PNG/JPG: trace light shapes on a dark background

Knife reach. The knife sits beside the nozzle, so near one edge of the bed the nozzle would leave its axis range before the knife gets there. When the printer is online the service reads its axis limits and the knife offset from _TRIAINA_VARS and places the design only where both fit. For example, with the shipped offset_x = 32 and an X axis maximum of 235 mm, the knife reaches X 203 at most. If the printer is offline the job says the area was not checked.

Bed size, margin, corner cutoff, overcut and feeds come from the service config.

What happens

file -> polylines (mm) -> size and place on the bed (lower-left at the margin)
     -> optional weeding border -> cut order -> blade-offset compensation
     -> G-code with CUT_PLUNGE / CUT_RETRACT -> preprocessor (CUTTER_MODE ... PRINTER_MODE)

Embedded bitmaps inside an SVG are skipped with a warning.

Cut order. Inner shapes are cut before the shapes around them (the hole of an O before its outline), so pieces cannot shift on the mat. Otherwise the nearest next shape is cut, and open lines may be reversed to save travel.

Blade offset. A swivel blade's tip trails the holder by about 0.25 mm, so an uncompensated knife rounds every corner. The holder is driven ahead of the design by that offset, and at corners sharper than cutoff_deg it swings on a small arc around the corner so the tip pivots in place. Closed shapes are cut overcut mm past their start so the ends meet. The tests check this by simulating the dragged tip: it stays within 0.02 mm of the design and reaches every corner.

Preview and checks

The job is converting while this runs (seconds; a large PDF or photo on a Pi 3 can take a minute), then ready. Before starting:

• open Preview: the bed, the margin, the cut lines (blue) and travel moves (orange, dashed);
• read the details column: size in mm, number of paths, a time estimate (a lower bound: acceleration and plunges are not counted), and any warnings such as skipped text;
• download the G-code if you want to inspect it.