Loose Bits Cleaner 1.0.0

Lists the loose parts of a mesh with volume (mm³), size (mm) and triangle count, previews the small ones by selecting them, and deletes them or keeps only the N largest parts. Blender 4.2 LTS or newer, tested on 4.2 LTS and 5.2 LTS.

Install

1. Extension zip (recommended): loose_bits_cleaner-1.0.0.zip. Drag it into Blender, or go to Edit > Preferences > Get Extensions, open the drop-down at the top right and choose Install from Disk.
2. Legacy zip: loose_bits_cleaner-1.0.0-legacy.zip. Go to Edit > Preferences > Add-ons > Install from Disk, then tick Loose Bits Cleaner.

The panel is in the 3D Viewport sidebar. Press N and open the Clean tab.

Clean a model, step by step

1. Import or open your model (File > Import > STL, OBJ, glTF or 3MF).
2. Set 1 Blender unit =. STL files are almost always in millimetres, so choose 1 mm. The line under it shows how many millimetres one unit is now.
3. Select one or more mesh objects and click List Loose Parts. The list shows every loose part, largest first: number, volume, size (bounding-box diagonal) and triangles. A cube icon means a closed part; a ~ before the volume means the part is open and its volume is estimated. Parts below the threshold are red with a bin icon. Nothing is changed yet.
4. Choose what Small means: Volume (below a number of mm³), Size (bounding-box diagonal below a number of mm) or % of largest (below a percentage of the largest part's volume). Set the threshold; the red marks in the list follow right away.
5. Click Select Small. Blender switches to Edit Mode (vertex select) with exactly the small parts selected, so you can see them. The arrow button on a list row selects just that part.
6. Click Delete Small Parts. The report says, per object, how many parts and triangles were removed and the volume that is kept. Ctrl+Z undoes it.
7. Or set Keep (for example 3 for a plate with three real parts) and click Keep Largest: every part smaller than the N largest is deleted.

Settings

A threshold of 0 never marks anything as small. The largest part of each object is never removed by Delete Small Parts.

How parts are measured

• Part: vertices connected by edges, the same as Blender's Separate > By Loose Parts. Loose vertices and edges without faces are parts too ("wire", 0 triangles).
• Volume: for a closed part, the exact enclosed volume in world space (scale and rotation applied, inside-out parts still positive). For an open part, the volume of a ball with the same surface area (marked ~).
• Size: the diagonal of the part's bounding box in mm.
• Order: largest volume first; ties by size, then triangle count.

Tips

• Not sure about the threshold? Use % of largest at 1 %: it works the same for a 20 mm and a 200 mm model.
• Flat flakes and open surfaces: the Size rule does not depend on volume at all.
• Always click Select Small first on a new model and look before you delete.
• Several objects selected? Each one is cleaned on its own and keeps its own largest part.

Limits

• Only loose-part removal: no hole filling, remeshing or repair.
• Parts that overlap without sharing edges count as separate parts.
• Works on the base mesh, not on modifier results (modifiers stay on the object).
• Linked duplicates share one mesh, so cleaning one cleans all of them.

More tools from Sonneblom Digitaal

At the bottom of the panel there is a small More tools from Sonneblom Digitaal box. AI Mesh Fixer opens the Superhive page of our separate, paid repair add-on in your browser; All our add-ons opens our shop page. Nothing is opened unless you click, and the add-on makes no network calls.

Licence

GPL-3.0-or-later. Made by Sonneblom Digitaal.