Rhino 3D Tip: Purge unused named definitions to reduce Rhino file size

Keep Rhino files lean and stable with Purge.

Purge removes unused named items so your model stays responsive and smaller on disk—ideal before archiving, sharing, or exporting. If you procure Rhino through NOVEDGE, consider making this part of your standard project handoff checklist.

What Purge cleans (without deleting actual geometry):

• Unused layers and sublayers
• Unused block definitions (including nested ones when requested)
• Unused materials, environments, and texture-based render content
• Unused linetypes, hatch patterns, and annotation styles (dimensions/text)

When to run Purge:

• After heavy iteration, imports, or exploded blocks
• Before exporting (STEP/OBJ/FBX) to reduce payload
• Prior to archiving or sending models to collaborators via NOVEDGE cloud services or similar workflows
• After replacing component libraries or updating block sources

How to run it efficiently:

• Type Purge and review items listed; confirm to remove unused entries.
• Use the command-line version -Purge to expose options. Enable Nested=Yes if you want to remove blocks that are only referenced by other unused blocks.
• Open BlockManager to audit block usage; the Purge button there is great for pruning orphaned definitions.

Safe housekeeping workflow:

• SaveIncremental to create a safety snapshot.
• Hide or detach external references and unused worksessions; referenced items cannot be purged while in use.
• Run -Purge and opt into the categories you truly don’t need (Blocks, Materials, Linetypes, Hatch Patterns, Annotation Styles).
• Optionally run ShrinkTrimmedSrf on heavy trimmed surfaces and SaveSmall when preparing files for transfer—Purge complements, but does not replace, these operations.
• Check File Properties > Statistics to compare object counts and file size before/after.

Tips and cautions:

• Purge never removes objects in the model space; it only deletes unused “named” definitions.
• Linked blocks: If a definition is still linked or in use in any instance, it will not be purged.
• Render assets embedded by plug-ins may repopulate after reopening if those plug-ins auto-load content—verify after a restart.
• If you rely on Named Views, Layer States, or Snapshots, do not purge them unless you’re certain they’re not part of your documentation workflow.

Automate it:

• Create an alias (Options > Aliases) named “pp” that runs -Purge, then confirm options at the command line.
• Add a toolbar button labeled “Clean” that runs -Purge, followed by SaveSmall, as your one-click housekeeping macro.

Result: cleaner file structure, faster opens/saves, reduced memory footprint, and fewer surprises when sharing with teams. For licenses, upgrades, and expert add-ons that complement a clean Rhino pipeline, check NOVEDGE.

You can find all the Rhino products on the NOVEDGE web site at this page.