kernelcad-print · diff
git:20260914.d5cc24c to git:20260914.4fa587e
39 added, 4 removed. Audit A to A.
---
name: kernelcad-print
- description: Close the physical print loop — slice a model to real G-code with a slicer CLI (export target:'model' format:'gcode'), then upload it to a network printer and start the print (send_to_printer). Load when the task is "print this" / "send this to my printer", not just "export the mesh".
+ description: Close the physical print loop — check FDM printability and pick the print orientation first (dfmSpec process 'fdm'), slice a model to real G-code with a slicer CLI (export target:'model' format:'gcode'), then upload it to a network printer and start the print (send_to_printer). Load when the task is "print this" / "send this to my printer" / "will this print without supports", not just "export the mesh".
---
# kernelCAD — print loop
## When to load this skill
Load when the task goes past a file on disk: the agent needs a physical
part, not just an STL/STEP. This skill covers the last two hops —
- model -> G-code, and G-code -> printer.
+ model -> G-code, and G-code -> printer — plus the check that should come
+ before both: will it print, and which way up.
+ ## Before slicing: FDM printability check
+
+ Declare the check in the script and evaluate it — it is cheaper than a
+ slice and says *why* a print would fail:
+
+ ```
+ dfmSpec({ process: 'fdm' }) // as modeled, +Z up
+ dfmSpec({ process: 'fdm', buildDirection: '+x', nozzleMm: 0.4,
+ maxOverhangDeg: 45, maxBridgeMm: 10, printer: 'generic-fdm' })
+ ```
+
+ `evaluate_script` / `kernelcad evaluate` then fail on unsupported overhangs
+ (`dfm.fdm.overhang-unsupported`), over-long bridges
+ (`dfm.fdm.bridge-too-long`), walls under 2 × nozzle
+ (`dfm.fdm.wall-below-nozzle`), and a part too big for the bed
+ (`dfm.fdm.exceeds-bed`); small holes/pins, low bed contact, and tip risk
+ warn. The overhang hint names the best axis-aligned rotation and what it
+ buys, e.g. `Rotate -90° about Y (.rotateY(-90), or dfmSpec buildDirection:
+ '+x'): unsupported area drops from 938.2 to 0.0 mm²`. The full per-part
+ report with all six orientations ranked is `verify({ check: 'dfm' })` (the
+ `fdm[]` block) or `kernelcad dfm <file> --json`.
+
+ Act on it by declaring that `buildDirection`. The gcode export below reads
+ it and rotates the part into that orientation before the bed gate and the
+ slicer, so the orientation that passed is the one that prints. Without an
+ FDM `dfmSpec` the part is sliced as modeled. If you choose to print with
+ supports instead, raise `maxOverhangDeg` to 90 and pass `supports: true`.
+
+ Worked example (fails as modeled, passes and slices on its side):
+ `examples/print-prep/wall-hook.kcad.ts` and
+ `examples/print-prep/wall-hook-on-side.kcad.ts`; cookbook snippet
+ `fdm-printability-and-print-orientation`.
+
## Slicing: `export` with `target: 'model'`, `format: 'gcode'`
```
export({
target: 'model', file: 'part.kcad.ts', output_path: 'part.gcode',
format: 'gcode',
options: {
format: 'gcode',
printer: 'generic-fdm', // bundled bed-size profile; default
material: 'pla', // 'pla' | 'petg'
layerHeight: 0.2, // mm; default 0.2
infill: 15, // percent, 0-100; default 15
supports: false, // default false
},
})
```
CLI equivalent: `kernelcad export gcode <file> -o <out.gcode>`.
This shells out to a real slicer CLI (OrcaSlicer, or PrusaSlicer if that's
what's on PATH) — never a placeholder. Detection order: `KERNELCAD_SLICER`
env var, then PATH lookup of `orca-slicer`, `prusa-slicer`, `PrusaSlicer`.
- Before invoking the slicer, the model's bounding box is checked against the
- selected printer profile's bed size. Result diagnostics:
+ Before invoking the slicer, the model's bounding box — in the FDM
+ `buildDirection` when one is declared — is checked against the selected
+ printer profile's bed size. Result diagnostics:
- `export.gcode.exceeds-bed` — the model doesn't fit the bed. Scale down,
split into sub-parts, or pick a printer profile with a bigger bed.
- `export.gcode.slicer-unavailable` — no slicer CLI found. Install
OrcaSlicer (or PrusaSlicer) and put it on PATH, or set
`KERNELCAD_SLICER` to its binary path. The tool never fakes a result.
On success, the result carries `gcodeStats` parsed from the slicer's own
G-code comments — real numbers, not estimates: `estimatedPrintTimeSeconds`,
`filamentUsedGrams`, `filamentUsedMeters`, `layerCount`, `maxZMm`.
## Sending it to a printer: `send_to_printer`
```
send_to_printer({
gcode_path: 'part.gcode',
protocol: 'octoprint', // 'octoprint' | 'moonraker' | 'bambu-lan'
host: '192.168.1.50',
api_key: '...', // octoprint only
})
```
- `octoprint` — `POST /api/files/local` with `X-Api-Key`; uploads and (by
default) selects + starts the print.
- `moonraker` — Klipper's `POST /server/files/upload`; uploads and starts.
- `bambu-lan` — Bambu Lab LAN mode: FTPS implicit-TLS upload on port 990
(user `bblp`, password = the printer's LAN access code), then an MQTT
print-start command on port 8883. Requires `access_code` and (unless
`start_print: false`) `serial`.
Always try `{ dry_run: true }` first when talking to unfamiliar hardware —
it validates connectivity/auth without uploading or starting a print.
Failures come back as `tool.send-to-printer.unreachable` (can't connect/
auth) or `tool.send-to-printer.upload-failed` (connected, but the upload
or print-start command was rejected).
CLI equivalent: `kernelcad print send <gcode-file> --protocol <p> --host <h> ...`
## Full loop example
See `examples/print-loop-bracket.kcad.ts` and the `gcode-export-and-print`
cookbook snippet (`lookup_cookbook`).