Rhino & GrasshopperPythonRhino 6–8 · built-in Python (rhinoscriptsyntax)MIT licenseIntermediate

Export Rhino curves to DXF, one file per layer

CAM software that wants each operation as a separate import turns "export the drawing to DXF" into "export the drawing N times, once per operation, hiding everything else first." This script does that automatically: it groups every curve in the document by its current layer, then runs Rhino's own Export command once per layer, so a model with roughing/finishing/engraving on separate layers comes out as three clean DXF files instead of one that needs re-splitting downstream.

Before you run it

Rhino 6, 7, or 8 (script uses rhinoscriptsyntax plus the -Export command line)
Curves organized onto layers that already match your intended DXF split (one layer per operation, typically)
Run once interactively first and check the exact Export prompts your Rhino version shows — the script assumes the default prompt accepts a single Enter

The code

GitHub

"""Export every curve on each layer to its own DXF file - one file per
layer, useful for CAM software that wants each operation on a separate import.

Rhino 6/7: Tools > PythonScript > Edit, paste, run.
Rhino 8:   ScriptEditor.
"""

import os
import rhinoscriptsyntax as rs

OUT_FOLDER = "C:\\DXF\\"   # must end with a backslash


def main():
    if not os.path.isdir(OUT_FOLDER):
        print("Folder not found: {}".format(OUT_FOLDER))
        return

    curves = rs.ObjectsByType(4, select=False)  # 4 = curve objects
    if not curves:
        print("No curves in the document.")
        return

    by_layer = {}
    for obj in curves:
        layer = rs.ObjectLayer(obj)
        by_layer.setdefault(layer, []).append(obj)

    exported = 0
    for layer, ids in by_layer.items():
        rs.UnselectAllObjects()
        rs.SelectObjects(ids)

        safe_name = layer.replace("::", "_").replace(" ", "_")
        path = os.path.join(OUT_FOLDER, "{}.dxf".format(safe_name))

        rs.Command('_-Export "{}" _Enter'.format(path), False)
        exported += 1
        print("{}: {} curve(s) -> {}".format(layer, len(ids), path))

    rs.UnselectAllObjects()
    print("{} layer(s) exported to {}".format(exported, OUT_FOLDER))


main()

What you get

C:\DXF\
├── Roughing.dxf
├── Finishing.dxf
├── Engraving.dxf
└── ...

Roughing: 12 curve(s) -> C:\DXF\Roughing.dxf
Finishing: 8 curve(s) -> C:\DXF\Finishing.dxf
Engraving: 3 curve(s) -> C:\DXF\Engraving.dxf
3 layer(s) exported to C:\DXF\

How it works

rs.ObjectsByType(4, select=False) grabs every curve in the document by its object-type code (4 = curves) — no manual selection needed, unlike the curvature-finder script's rs.GetObject.
Grouping into a {layer: [ids]} dictionary first, then looping over the groups, is what turns "all curves" into "one DXF per layer" — the export step only ever sees one layer's curves selected at a time.
rs.Command('_-Export "..." _Enter', False) is the standard way to script a command that would otherwise open a dialog: the leading - suppresses the modal UI, and _Enter accepts the follow-up prompt's default.
Layer names are sanitized (:: and spaces replaced) before becoming filenames — Rhino allows characters in layer names, especially nested-layer separators, that most filesystems don't.

Gotchas & honest limits

Test the `-Export` prompt sequence interactively once before trusting this unattended — depending on your Rhino version and DXF export settings, there can be more than one follow-up prompt (units, ACAD version), and this script only sends one _Enter.

Curves on a locked or hidden layer are still returned by ObjectsByType but can't be selected or exported — a hidden layer will silently produce an empty or missing DXF for that layer.

Nested layers (Parent::Child) are flattened into one filename per full layer path, not one file per parent — usually what you want for a CAM-operation split, but check it matches your layer structure.

This exports curves only — surfaces, meshes, and annotations on the same layers are ignored, by design, since DXF/CAM handoff is almost always curve geometry.

Goes deeper

Cutting a 45-minute job to 20 with Rhino spline links

Want this adapted to your shop — or built into a real tool?

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