Repairing Meshes

Check and Repair Meshes

A good start is to try Rhino's built-in mesh repair. This is very helpful for resolving small errors, for example if there's a stray point or a duplicate unused edge.

Select a mesh and use the command [MeshRepair].

  1. Check the Mesh, ignore the first Repair Mesh command and press Next to access the first repair menu.

  2. Repair Menu 1: is great for doing mesh clean-up, tick all the boxes and click Repair.

  3. Repair Menu 2: provides an interface for accessing these Rhino commands. These may not always work and require manual Mesh Manipulation.

Manual Mesh Manipulation

For most cases, quick manual fixes are easier to control than using auto-repair. Mesh objects are easily manipulated unlike NURBs objects, you can simply access their sub-objects and transform them like you would any other object.

Transforming Sub-objects

When just moving and 'joining' vertices or edges or faces together to fix things like small gaps, you can select its sub-vertices/edges/faces using [Ctrl+Shift+LMB]

Faces can be flipped using the [Flip] command.

Adding New Geometry

You can create new face geometry through usual nurbs methods and mesh them, or alternatively you can use [3DFace] to quickly make mesh faces. Use [Join] to add it to the mesh.

Mesh Repair Services and Software

For bad meshes that are proving to be difficult to troubleshoot the following services and software may be useful in repairing naked edges and non-manifold edges. Once the mesh has been repaired the file should still be checked as there still may be a possibility that the 'repaired mesh' is still bad.


Meshmixer is a free software for working with meshes. It can be helpful when cleaning up 3D models prior to 3D printing.

Method 1:

  1. Open Meshmixer and import your object.

  2. Analysis > Inspector will bring up all holes.

    1. Adjust the hole filling settings as desired

    2. Apply them to detected holes in the viewport individually, or select Auto Repair All.

Method 2:

  1. Open Meshmixer and import your objects

  2. Edit > Make Solid will automatically fill holes and re-mesh your entire object.


  1. Meshmixer can be used to further adjust the mesh if required, with basic booleaning, sculpting and procedural mesh edits like hollowing.

  2. Export the object back out

Microsoft 3D Builder

Windows ONLY; otherwise please install through the Microsoft Store app, importing bad meshes will automatically prompt a fix.

To attempt to repair a mesh:

  1. Open > Load Object and Select your files to repair (common filetypes: .stl, .obj, .3mf, .ply)

  2. Click Import in the top left at the appropriate scale.

Option 1: Voxelisation

This process remeshes the entire object, which may result in a different mesh outcome.

  1. You will see the object highlighted with a red base and a notification in the bottom right - attempt repair by selecting the object and then the notification.

  2. The red base will disappear if the geometry has been fixed - but this does not mean that it is a valid mesh still, save it out and check it in your 3D software of choice to confirm.

  3. You can use 3D Builder to also make boolean edits to the mesh through the Add/Edit menu.

Option 2: Split Edit

Ignore the automatic mesh repair tool and use the split tool to cap objects

  1. Ignore the red outline + mesh repair prompt.

  2. Select the object

  3. Edit > Split

    1. Choose the appropriate settings, above or below.

    2. Drag the section plane to move it up/down.

    3. Use the gizmos to rotate the section plane

  4. Apply it to trim and cap.

Prusa Slicer

Prusa slicer is a slicer used for our Open Access 3D printers, it has a version of Netfabb installed. As its main function is a slicer, this mesh repair feature is a niche but accessible way to access Netfabb.

  1. Install Prusa Slicer, if the configuration menu appears, you may skip these options.

  2. Import your .stl model by dragging+dropping into the 3D viewport or by going through the File menu. (You may get some warnings like your object is too big, but as you are only repairing the .stl, ignore these warnings.)

  3. If there is an issue with the mesh, there will be a warning icon next to its name (usually found in the panel on the right.)

  4. Right-click this icon to start the repair.

  5. If the repair is successful, you can right-click the mesh in the viewport and export .stl.

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