Rhino 3D Tip: Smooth, Artifact-Free Edge Transitions in Rhino

Creating silky, artifact-free edge transitions in Rhino hinges on planning, clean inputs, and the right tool for the continuity you need.

• Choose the right approach:
  • FilletEdge (solids): constant-radius, G1 (tangent) continuity. Best for mechanical parts.
  • BlendEdge (solids): curvature-continuous (G2) “fillet-like” transitions for softer highlights.
  • FilletSrf / BlendSrf (surface-by-surface): precision control and repair when solid fillets fail.
• Set tolerances strategically:
  • Absolute tolerance ≈ 1/10 of your smallest intended radius (example: 0.01 if the smallest fillet is 0.1).
  • Model in real units; avoid scaling after filleting. Set this upfront in File > Properties > Units.
• Prep geometry for success:
  • Simplify: MergeAllFaces, ShrinkTrimmedSrf, unify surface directions (Dir), and eliminate tiny sliver faces.
  • Avoid stacked edges at intersections; consider remodeling overly segmented surfaces before filleting.
• Solid-first workflow (quick and robust):
  • For mechanical aesthetics, run FilletEdge with Chordal or RollingBall as needed. Use Setback at multi-edge corners to avoid pinching.
  • For visual smoothness, use BlendEdge with Continuity=Curvature (G2). Add handles to control bulge and maintain section quality through transitions.
  • At junctions, test Corner=Round or Setback variants to keep highlight flow continuous.
• Surface-by-surface method (when edges fail):
  • Untrim and ExtendSrf adjacent faces so they overlap cleanly.
  • Use BlendSrf with Curvature continuity on both sides for true G2 transitions. Shape handles let you manage roll and cross-section.
  • Trim back with Trim/Split, then enforce continuity with MatchSrf (G2, Preserve isocurve structure where possible).
  • Fill tricky corners using BlendSrf patches or MatchSrf to the surrounding blends in G2.
• Verify smoothness (don’t trust shaded view alone):
  • Zebra and Analysis > Curvature should show continuous, unbroken bands across transitions.
  • Use CurvatureGraph on input curves: smooth graphs prevent lumpy blends.
  • ShowEdges to catch naked/non-manifold edges early.
• Corner strategies:
  • Prefer Setback controls at vertices with >2 intersecting edges to preserve G2 highlight flow.
  • For organic forms, hand-build a small corner patch with BlendSrf and G2 matching to all neighbors.
• Performance and iteration:
  • Keep copies of pre-filleted surfaces on a locked layer for quick reworks.
  • Use History with BlendSrf when feasible to iterate shapes fast.
  • Create Named Selections for recurring edge sets to test multiple radii/bulges efficiently.

Pro tip: blurring the line between “fillet” and “blend” is the secret to continuously smooth results. Use constant-radius fillets where function demands it, and switch to curvature blends wherever the eye reads reflections.

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