Rhino 3D Tip: Rhino Section — Precise Cut Profiles for Documentation and Fabrication

Use Rhino’s Section command to extract precise cut profiles for documentation, fabrication, and QA.

When to use Section:

• Generate true intersection curves where solids, polysurfaces, SubD, and meshes meet a cutting plane.
• Create profiles for CNC/waterjet, laser templates, or architectural sections.
• Produce clean 2D curves for drawings, hatching, and downstream CAD/CAM.

Preparation for reliable results:

• Set Units and Model Tolerance early. Tighten tolerance for small parts; loosen slightly for large sites.
• Organize a “Sections” layer with distinct color/linetype. Consider one layer per station/elevation.
• Verify geometry health: run Check on polysurfaces; repair meshes with MeshRepair.

Core workflow:

1. Select your objects (solids/surfaces/meshes/SubD).
2. Run Section and define the cutting plane:
   • Pick 2 or 3 points for an ad‑hoc plane.
   • Use the current CPlane or a Named CPlane for repeatable alignment.
   • Use Ortho/SmartTrack and Osnaps for accuracy.
3. Place resulting curves on your “Sections” layer and Group them if needed.
4. Optionally Hatch closed profiles and add annotations/dimensions in Layouts.

Multiple stations efficiently:

• Use Contour along a direction vector to create evenly spaced sections (e.g., every 100 mm or at floor elevations).
• Name layers by station (S-1000, S-1100, …) for quick filtering and plotting.

Quality tips for clean sections:

• Closed section curves on a solid usually indicate watertight geometry. Use ShowEdges (Naked Edges) to diagnose leaks.
• Simplify heavy results: SimplifyCrv to merge co‑linear segments; Rebuild (lightly) for fairer profiles where manufacturing allows.
• For mesh-heavy models, expect polylines; Weld and ReduceMesh beforehand for better performance.

Clipping vs. Section:

• ClippingPlanes are visual and dynamic; they don’t produce real curves.
• Section creates actual geometry you can measure, hatch, export, or send to CAM.

Documentation and export:

• Use Make2D in Detail views to combine Section curves with hidden/visible line styles.
• ExportSelected to DWG/DXF for drafting or to SVG/AI for graphics; set appropriate export tolerances.

Advanced workflows:

• Drive live sections in Grasshopper for parametric studies and batch exports.
• Pair Section with Project or Pull when you need profiles aligned to a specific construction plane or surface.
• For complex assemblies, section sub-models individually, then reference them into a master file to keep performance snappy.

Troubleshooting:

• Missing or fragmented curves: increase Model Tolerance slightly and retry; verify that objects are valid (Check).
• Unexpected gaps on meshes: refine mesh (smaller edge lengths) or convert critical parts to NURBS where feasible.

Pro tip: standardize section conventions (layer names, colors, linetypes, hatches) in a template file so teams produce consistent profiles every time.

Need Rhino or pro-grade plugins to enhance your sectioning workflow? Get them from NOVEDGE. Looking for best-practice advice or volume licensing? Talk with the experts at NOVEDGE—they’ll match tools and training to your pipeline.

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