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Mesh Healer finds the most common mesh defects and fixes them in one panel: disconnected parts, holes, self-intersections, flipped normals, zero-area triangles and small tunnels. Use it before you 3D print, simulate or measure a scan or a downloaded model. Mesh Healer is part of the Makers plan.
Mesh Healer has two modes. Local Repair fixes only the faulty areas and leaves the rest of the surface as it is. Auto Repair builds a completely new surface for the whole model.
Repair a mesh in four steps
- Select the mesh in the scene tree and click Mesh Repair › Mesh Healer. You can also click the Mesh Healer icon on the toolbar above the viewport.
- Click Local Repair if it is not selected (Mesh Healer remembers the last mode). Mesh Healer inspects the mesh and shows a counter next to each check: red means defects were found, a green 0 means none. Disconnected Parts, Holes and Self-Intersections are checked by default.
- Select the checks you want to fix and click Repair Selected.
- Look at the counters again and at the Information panel (Triangles, Holes, Components).
When you open a file with defects, MeshInspector shows the message The mesh contains errors. Click Repair Mesh to open Mesh Healer on this mesh, or Skip. Select Do not launch on file upload if you do not want this message.
For example, a head scan opens with 29 holes and 10 components. Mesh Healer counts 2 large and 8 small disconnected parts, 4 large and 25 small holes, and no self-intersections:
After Repair Selected, the small parts are gone and the large parts are joined (1 component), all 25 small holes are filled, and the 4 large holes stay open:
What may remain after Local Repair
- Large holes. Local Repair fills only small holes. A hole is large when its perimeter is longer than Minimum Perimeter: by default, one third of the diagonal of the model's bounding box. Mesh Healer leaves large holes open because they can be intended openings. The tooltip of the Large counter says: "To fix large holes please go to Fill Holes plugin or rebuild model." To close all of them in one step, use Bridge Fill All Holes; to close only some, use Fill Holes. Then run Mesh Healer again: a large patch can cut through the surface (see the worked example).
- Issues that one pass could not fix. If small holes, self-intersections or zero-area triangles remain after the repair, MeshInspector shows the warning "Some mesh issues remain. Please consider using Rebuild Model". Select the remaining checks and click Repair Selected again, or try a recipe below, or rebuild the model with Auto Repair.
What Mesh Healer checks
| Check | What it finds | What Repair Selected does |
|---|---|---|
| Disconnected Parts (on by default) | Separate parts of the mesh. Small parts have less area than Minimum Area (0.2% of the mesh area by default), the others are Large. | Removes small parts and unites large intersecting parts (Boolean union). |
| Holes (on by default) | Open boundaries, split into Large and Small by Minimum Perimeter. | Fills small holes. Large holes stay open. |
| Self-Intersections (on by default) | Triangles that cut through other triangles of the same mesh. | Cuts out the area and fills it again, or smooths it (see Cut And Fill below). |
| Flipped Normals | Parts whose triangles face inward. | Flips the wrongly oriented parts. |
| Zero-Area Triangles | Degenerate, needle-like triangles that have almost no area. | Fixes them. |
| Small Tunnels | Small handles and through-holes in the mesh, up to Maximum Tunnel Length. | Cuts the tunnels and fills the cuts. |
| Thin Walls (Printability Checks) | Walls thinner than Critical Thickness. | Finds only. Mesh Healer does not fix thin walls. |
| Undercuts (Printability Checks) | Areas hidden from the chosen direction (Axis). | Finds only. |
When several checks are selected, Mesh Healer fixes them in this order: small parts, flipped normals, holes, small tunnels, self-intersections, large parts, zero-area triangles.
The Selection block helps with manual fixes. Mesh Healer selects the faulty triangles it finds. Delete Selection deletes the selected triangles, which leaves a hole you can then fill; Save Selection on Exit keeps the selection after you close the tool.
Restart on Mesh Selection Change (on by default) restarts Mesh Healer when you select another mesh in the scene tree.
Advanced Mode
Turn on Advanced Mode (next to Inspect and Repair) to change how each check detects and repairs defects. A changed detection setting takes effect when you click Apply next to it. Save Settings, Load Settings and Reset Settings store your settings in a JSON file and restore the defaults.
| Check | Main settings |
|---|---|
| Disconnected Parts | Minimum Area: parts with a smaller share of the mesh area are small and are removed. |
| Holes | Minimum Perimeter: holes with a longer perimeter are large and are not filled. |
| Self-Intersections | Cut And Fill: on, the area is cut out and filled; off, it is only relaxed (smoothed). Mimic Patch keeps the patch close to the original surface. Touches as Self-Intersections also counts triangles that only touch. |
| Zero-Area Triangles | Triangles Aspect Ratio, Subdivide, Forced Fix: removes bad triangles with their surroundings and fills the hole in the last pass. |
| Flipped Normals | Mode, Virtual Fill Holes, Component Threshold: flips a part when at least this share of its area faces the wrong way. |
| Small Tunnels | Maximum Tunnel Length, Build Co-Loops. |
Repair Resolution and Deviation Map
Repair Resolution is the "maximum distance the healed mesh may deviate from the original surface". Mesh Healer sets it from the size of the model; choose a value that matches your printing resolution or is finer. A smaller value keeps more detail but takes longer, especially in Auto Repair.
Show Deviation Map colors the repaired mesh by its distance to the original: red where material was added, blue where it was removed. The scale goes from minus to plus Repair Resolution. Select Discrete Palette to see the colors as steps.
After Local Repair the map may look almost unchanged: removing parts and filling holes does not move the original vertices, it only adds new triangles in the holes.
Auto Repair: rebuild the whole model
Auto Repair builds a new surface for the whole model from voxels. It closes holes and removes self-intersections in one step, but it replaces every triangle, so small details within the voxel size can change.
- Click Auto Repair in Mesh Healer.
- If the mesh has holes, you see "Model has N holes. It is recommended to fix them before using Auto Rebuild." Fill the holes first (Local Repair or Fill Holes), or check the result carefully.
- Under Resolution, choose Standard, High, Ultra or Custom (your own voxel size). Finer resolution keeps more detail but takes longer.
- Click Auto Rebuild Model.
The settings under Advanced are the same as in Mesh Repair › Auto Repair Mesh; they are explained in Auto Repair Mesh. Auto Repair Mesh can also rebuild several selected meshes at once.
A rebuilt mesh usually has more triangles than the original, and loose fragments of a scan turn into separate solid parts instead of disappearing. Remove small parts with Local Repair before the rebuild, and reduce the triangle count afterwards with Simplify.
Recipes
Short fixes for cases where one click of Repair Selected is not enough. The video STL Repair Examples with Mesh Healer: No Rebuild Function shows these cases on real models.
Repairs do not work: flipped normals
Wrongly oriented triangles confuse the other repairs. Turn on Flipped Normals and click Repair Selected, or fix the orientation first with Flip Normals, then run Mesh Healer again.
Unwanted parts stay in the model
Parts that do not intersect the main body and are larger than Minimum Area count as large and stay. To remove them, turn on Advanced Mode, increase Minimum Area for Disconnected Parts, click Apply, then Repair Selected. To keep only the largest part, use Mesh Repair › To Components › Keep Largest Component (see Keep Largest Component). Check hidden inner parts with a section first: in jewelry, for example, a gem can have an inner shell on purpose.
A large hole is not filled
Close it with Bridge Fill All Holes or Fill Holes. Alternatively, increase Minimum Perimeter for Holes in Advanced Mode, click Apply and Repair Selected. A very large opening, such as the open bottom of a scan, gets a big patch: check that this is what you want, and run Repair Selected again to fix self-intersections the patch may create.
Self-intersections remain
In Advanced Mode, change Cut And Fill for Self-Intersections (on cuts the area out and fills it, off only smooths it) and click Repair Selected again. If many intersections remain, rebuild the model with Auto Repair or Rewrap.
Zero-area triangles remain
Turn on Zero-Area Triangles. In Advanced Mode, select Subdivide and Forced Fix for this check, then click Repair Selected. If some remain, delete the selected faulty triangles with Delete Selection (you can grow the selection first with Select › Expand Selection), and run Repair Selected with Holes checked to fill the gap.
Worked example
The head scan from the screenshots above is a typical scan with defects. To make it watertight:
- Run Local Repair with the default checks. It removes 8 small fragments, joins the 2 large parts and fills all 25 small holes. The 4 large holes stay open.
- Close them with Bridge Fill All Holes. The mesh has no holes now, but the large patch over the open face cuts through the surface: Mesh Healer finds 1 329 self-intersections.
- Click Repair Selected in Mesh Healer again. The self-intersections are fixed.
| Step | Triangles | Holes | Components | Self-Intersections |
|---|---|---|---|---|
| Opened file | 71 263 | 29 | 10 | 0 |
| After Local Repair | 71 597 | 4 | 1 | 0 |
| After Bridge Fill All Holes | 73 992 | 0 | 1 | 1 329 |
| After Local Repair again | 72 720 | 0 | 1 | 0 |
For a model with many self-intersections and zero-area triangles, watch Advanced Model Repair in MeshInspector: Statue of Liberty Case. The order used there:
- Run Local Repair with the default checks.
- If the result has new holes or lost details, rebuild with Auto Repair, using Custom resolution with a smaller voxel size.
- If the model is still made of several parts, split it with Mesh Repair › To Components and delete the parts you do not need.
- Fix the remaining self-intersections with Cut And Fill turned off.
- Delete the remaining zero-area triangles (Delete Selection) and fill the resulting holes with Repair Selected.
FAQ
Should I use Local Repair or Auto Repair?
Start with Local Repair: it keeps the original surface and changes only faulty areas. Use Auto Repair when Local Repair cannot fix the self-intersections or the model is too damaged, and accept that the whole surface is rebuilt.
Why are some holes not filled?
They are large holes: their perimeter is longer than Minimum Perimeter. Close them with Fill Holes or Bridge Fill All Holes, or raise Minimum Perimeter in Advanced Mode.
Does Mesh Healer fix thin walls and undercuts?
No. Thin Walls and Undercuts only find and highlight these areas. Thicken thin walls in your design or with other tools before printing.
Why does the Deviation Map show almost no change after Local Repair?
Removing parts and filling holes does not move the original vertices; only the new triangles in the holes differ from the original. So most of the surface has zero deviation.
