lril3d-slice

name	lril3d-slice
description	Use when a verified part needs turning into machine instructions — print time, filament grams, AMS slot mapping, purge waste, or a G-code preview. Also when the user asks how long a print will take or what it will cost.

lril3d-slice — G-code, time, and grams

Thin skill, thick library. No preset names or thresholds belong in this file — they live in profiles/slicer.json. Read PRD.md §12 and §9.

This skill does not send anything to a printer. --export-3mf produces a file; putting it on the printer is lril3d-print's job, behind its approval gate. Hand off to that skill rather than uploading anything here, and never as an unprompted next step — sending is a decision the user makes, not a convenience you add.

Slice

from threedp import slicer
result = slicer.slice_part("models/<name>/out/part.stl", material="PLA")
print(result)

Materials are the keys under presets.filament in profiles/slicer.json. outdir defaults to a slice/ directory beside the input. export_3mf="sliced.3mf" takes a bare filename.

What the wrapper refuses, and why that matters more than what it returns

slice_part raises SliceRejected rather than returning a number the slicer did not produce. When it does, report the refusal. Do not retry with different settings hoping for a number, and do not present a rejected slice as a small part.

• 0.00 g is a rejected slice, not a light part. The vendor presets are not self-contained and the CLI does not resolve their inherits chain, so an unflattened preset slices successfully at a filament density of zero. The wrapper flattens; if you ever see a zero, the flattening broke.
• return_code 0 is not success. Asking for a plate that does not exist returns 0 and "Success." and slices nothing at all.
• A non-zero return code does not mean nothing was produced, either. Both signals are unsound alone, which is why four conditions are checked.
• A print time of zero is refused for the same reason a mass of zero is.

Read the result

slice    plate 0   25m 08s (1528 s)   10.85 g of PLA (density 1.26 g/cm3, filament_id GFA00)

filament_id is not cosmetic: use_ams is silently ignored unless it is set, which prints successfully from whatever happens to be loaded. printer.assert_3mf_is_dispatchable checks it on the actual file before any send.

AMS mapping and purge

slicer.ams_mapping(["PETG", "PLA"])          # -> [2, 0]
slicer.purge_waste(matrix, [0, 1, 0], multiplier=1.0, density=1.26)   # -> (mm3, grams)

The mapping is forward-indexed (correction C5): array position is the filament index inside the 3MF, array value is the AMS slot. Backwards, it prints in the wrong colours and looks like a slicing bug. Values are not capped at 0–3 — a second AMS unit occupies 4–7 — and the external spool is 254.

ams_mapping maps the inventory faithfully, including when the inventory is wrong. It knows nothing about the printer, on purpose. Before a print goes anywhere near the machine, lril3d-print reconciles profiles/filaments.json against live telemetry and refuses on a mismatch; if you are reporting a slot to a user outside that flow, say it is what the inventory claims, not what is loaded.

An external spool has no AMS slot and mapping to one raises — it is fed by hand, and it is not "slot 4". Purge with no density returns grams of None, never 0.0; report the volume and say the mass is unknown.

Preview it

from threedp import gcode
gcode.write_preview(result.gcode, "models/<name>/out/part.preview.json")

The viewer picks that file up and hot-reloads it. The preview is a channel, not a gate — the same rule as renders. If it says TRUNCATED, say so; a preview that was cut short is not the whole toolpath.

When it does not work

1. SlicerNotFound — Bambu Studio is not installed at any configured path. The error lists what it tried. Set THREEDP_SLICER to the executable rather than editing code.
2. return_code -17, "not compatible with the process preset" — the machine or process preset was renamed. A process preset's compatible_printers is a list of printer names.
3. preset ... not found — a Bambu Studio update renamed something in the profile tree. The error names the path it looked in; fix profiles/slicer.json.
4. A blank preview on the P1S screen means the G-code was sent, not the 3MF. The CLI's G-code carries no thumbnail block at all — one thumbnail_size config line and nothing else, which is what Phase 2 measured. The 3MF does: Metadata/plate_1.png at 512×512, a real render (correction C7). lril3d-print sends the 3MF, so the screen preview works. If it is blank, the wrong artefact went across.
5. Timeout — a comparable part slices in about a second on this machine, so a timeout is a hang rather than a slow model. Do not raise timeout_s to make it pass.

Non-negotiable

Report the measured numbers from the SliceResult and nothing else. Banned: "roughly", "about 10 grams", "should take around". The result carries exact values; use them. If the slice was rejected, the sentence is "the slicer refused this result because ...", never a softened estimate.