Repair Non-Manifold STL
Detect non-manifold edges and duplicate geometry in an STL file and safely resolve the deterministic cases — ambiguous topology is preserved and reported, never fixed by deleting triangles arbitrarily.
Your STL stays on this device. MeshWrench repairs it locally in your browser.
Binary or ASCII STL, up to 150 MB. This limit protects your browser from freezing — it isn't a Pro restriction.
Processed locally — nothing was uploaded.
Planned operations
Operations
Unresolved problems
None — every targeted problem was resolved.
Hole-fill details
Repairing many files? Batch repair is planned for Pro.
Before / after
| Measure | Before | After |
|---|---|---|
| Watertight verdict | ||
| Triangles | ||
| Unique vertices | ||
| Shells | ||
| Boundary edges | ||
| Non-manifold edges | ||
| Winding conflicts | ||
| Self-intersections |
Batch processing is a Pro capability.
Pro batch tools are being prepared. Purchasing is not available yet.
Drag files here, or click to browse
STL files only, same limits as single-file repair.
Manage presets
Review the plan before anything is changed
- Detected issues
- Planned operations
- Skipped operations
- Eligibility
- Warnings
How non-manifold repair works here
- MeshWrench analyzes your file and reports the exact non-manifold edge count.
- Duplicate-face and degenerate-triangle cleanup run — the deterministic causes of most non-manifold edges.
- MeshWrench re-checks edge incidence on the cleaned result and reports what's still unresolved, if anything.
- You get an honest before/after count — never a claim that every non-manifold edge was fixed unless it verifiably was.
Deterministic vs. ambiguous non-manifold cases
Deterministic: a non-manifold edge caused by a duplicate or degenerate triangle that this tool's own cleanup can identify precisely and remove. Resolving the duplicate/degenerate naturally resolves the excess edge incidence too.
Ambiguous: an edge genuinely shared by three or more otherwise-valid triangles, with no identifiable "extra" one. This tool preserves the geometry exactly and reports the edge as unresolved — it never deletes an arbitrary triangle just to force the incidence count down to two, since a wrong guess would silently remove real geometry.
A realistic outcome
A repair result of "improved" or "partially repaired" — non-manifold count reduced but not zero — is a legitimate, honest outcome, not a failure of the tool. The before/after comparison always shows the exact count on both sides.
Limitations
- Vertex/edge fan-splitting for ambiguous non-manifold cases is not implemented in this phase — a disclosed scope decision, not an oversight.
- Self-intersecting geometry is detected, never resolved.
- Fixing non-manifold topology doesn't by itself guarantee a model will print successfully.
Frequently asked questions
What is a non-manifold edge?
An edge shared by more than two triangles. A real, physical surface never has this — every edge should border exactly two faces (or one, at a boundary). Non-manifold edges usually come from duplicate/overlapping geometry or a genuine modeling error.
Can every non-manifold edge be fixed automatically?
No — and this tool is explicit about that. Only DETERMINISTIC causes (duplicate or degenerate triangles already covered by this tool's own cleanup) are resolved. A genuinely ambiguous non-manifold edge is preserved and reported as unresolved, never fixed by arbitrarily deleting a triangle to force the count back to two.
Why not just delete extra triangles at a non-manifold edge?
Because which triangle is "extra" is often not determinable without guessing — and a wrong guess can silently remove real geometry. This tool only removes triangles it can identify precisely as duplicates or degenerates; anything else is left for you to inspect.
Does removing duplicate faces fix non-manifold edges?
Often, yes — a common cause of a >2-triangle edge is an exact or reverse-winding duplicate face sharing that edge. Duplicate-face removal runs as part of this tool's cleanup and frequently resolves the non-manifold count on its own.
Is my file uploaded to check for non-manifold edges?
No. Detection, repair and verification all run locally in your browser, in a background Web Worker.