Rhino 3D Tip: Remove Stacked Geometry with SelDup

Keep your files lean and reliable by eliminating stacked geometry. Here’s how to use SelDup to quickly find and remove duplicates in Rhino.

Why duplicates matter:

• Unexpected Boolean failures and surface joins due to coincident edges.
• Render flicker (Z‑fighting) from overlapping faces.
• Bloated file sizes, sluggish display, and slow Make2D results.
• Double-counted areas/lengths in Mass Properties and drawings.

Core workflow (fast and safe):

• Check tolerance first: File > Properties > Units. A realistic Absolute tolerance helps Rhino identify true coincidences without flagging near-misses.
• Run SelDup. Rhino selects visible, unlocked objects that are exact duplicates.
• Inspect the selection:
  • Use ZoomSelected to review the stack.
  • Toggle SelectionFilter (status bar) to limit by type (e.g., only curves) before re-running SelDup.
  • Use Isolate to focus on the problem area, then Show to return.
• Decide the action:
  • Clean and commit: Delete to remove extras immediately.
  • Review later: Move or ChangeLayer to a “Duplicates_Review” layer and lock it.

Pro tips for accuracy and speed:

• Prevent accidental copies: When using Gumball, Alt-drag creates duplicates. If you only want to move, avoid Alt or set Gumball’s DragStrength to a comfortable value to reduce mis-drags.
• Block instances: Identical block instances stacked in place are valid duplicates. SelDup will select the extras—delete with confidence if locations and names match your intent.
• Curves versus edges: If you intentionally used DupEdge for modeling, hide or lock breps before SelDup so you only test free curves, avoiding false positives you plan to keep.
• Large scenes: Run SelDup per layer or per object type using SelectionFilter to minimize the selection scope and keep feedback snappy.
• Audit before export: Always SelDup on:
  • Make2D source geometry to prevent doubled linework.
  • Laser/Waterjet outlines to avoid overcuts.
  • Render sets to eliminate Z‑fighting.

Handy one‑liners (macros you can assign to a button or alias):

• Delete duplicates now: ! _SelDup _Delete
• Review with focus: ! _SelDup _Isolate

Related clean‑up tools to pair with SelDup:

• Purge to remove unused blocks, layers, and materials once duplicates are gone.
• SelSmallObjects to catch tiny fragments created during imports or trims.
• SimplifyCrv / FitCrv to reduce near-overlapping curves that are not exact duplicates but cause clutter.
• Audit3dm before archiving to confirm model integrity.

Workflow checkpoint:

• Set realistic tolerances.
• Filter by type when needed.
• Run SelDup and verify counts.
• Delete or park in a review layer.
• Purge and save.

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