CheckMesh

Checks mesh objects for errors, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh objects.

Use the CheckMesh command when generating an STL mesh for rapid prototyping to troubleshoot imported and Rhino-generated meshes. Using CheckMesh and then fixing any indicated errors will minimize down-process errors. The command test results along with detailed information about the mesh. Use this information as a checklist for mesh repair.

Errors

Degenerate faces

Fix with the CullDegenerateMeshFaces command.

Zero length edges

Zero-length edges typically are the result of degenerate faces. Fix with the CullDegenerateMeshFaces command.

Non manifold edges

Use the CullDegenerateMeshFaces command and then fix with the ExtractNonManifoldMeshEdges command.

Naked edges

Naked edges are allowed, but cause problems with rapid prototyping. Use the ShowEdges command to help find them. Try the FillMeshHole, FillMeshHoles, or MatchMeshEdge commands to remove naked edges.

Duplicate faces

Fix with the ExtractDuplicateMeshFaces command.

Faces that could make it better if their directions were flipped

Fix with the UnifyMeshNormals command.

Disjoint pieces

Fix with the SplitDisjointMesh command.

Unused vertices

Unused vertices do not usually cause a problem, and there are no commands to for removing them.

Text Window Options

Copy All

Copies all text in the window to the Clipboard

Save As

Saves the contents of the window to a text file.

Close

Closes the window.

CullDegenerateMeshFaces

Deletes mesh faces that have 0 area, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh objects.

• Note: If any vertices are orphaned in the process, they are also removed

PatchSingleFace

Fills a mesh hole with a single mesh face, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select two edges or vertices of a mesh.

Options

JoinMesh

If Yes, the new faces are joined to the original mesh.

FillMeshHole

Fills a selected hole, which helps clean up, repair, and close mesh files for rapid prototype printing.

Fills a hole in the mesh selected by picking the hole edge. The command searches around the naked edge you select and attempts to create a closed boundary to fill.

Steps

• Select a mesh hole boundary.

Note: Mesh boundaries and other subparts cannot be selected in a shaded view.

Options

JoinMesh

If Yes, the new faces are joined to the original mesh.

FillMeshHoles

Fills all holes in a polygon mesh object with triangular faces, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh objects.

UnifyMeshNormals

Changes the normal direction of the faces in a mesh object so they all point in a consistent direction, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select a single unjoined mesh.

• The normals of all the faces of the mesh will now point to one side of the mesh.

  The UnifyMeshNormals command changes the direction of the surface normals of a mesh object so all normals face the same direction. This command is useful for tidying up your mesh objects for export into 3D Studio. Rhino's Advanced Display Settings let you display the front and back faces in different colors. This will show you whether the normals need to be unified.

Notes

• If UnifyMeshNormals doesn't seem to affect your mesh, explode it. Once the normals are correct, re-join the meshes.

• A polygon can have two types of normals: vertex normals and a face normal.

• All polygons have a face normal direction, but many polygon meshes do not have vertex normals. For example, 3DFace objects, mesh primitives, and polygon meshes imported in formats other than 3DM and 3DS do not have vertex normals.

  In general, the order of the vertices in a polygon determines the face normal direction. The order of the vertices should be either clockwise or counterclockwise. You can determine the normal direction from the vertices using the right-hand rule.

  You use the UnifyMeshNormals command primarily to make sure that the vertex order of all polygons in welded mesh is the same.

Example

A potential work flow is as follows:

1. Import STL file with holes in it.

2. Fill the holes in the mesh.

3. Weld the mesh setting the welding angle to 180 to make sure all vertices get welded.

4. Use UnifyMeshNormals.

5. Turn on one sided rendering and shade the model to see if the mesh face normals point in or out. If you see inside the mesh, normals point the wrong way.

6. Use Flip to change the mesh normal direction if necessary.

7. Export in desired format.

AlignMeshVertices

Forces mesh vertices within a specified distance to the same location, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh objects or click an option.

• If the distances between mesh vertices are smaller than the value of DistanceToAdjust, the vertices are forced together.

  This command is useful for fixing areas that have many vertices that should be in the same spot but for some reason are not.

Options

SelectVertices

Select vertices to align.

SelectNakedEdges

Select naked edges to align all vertices on the edge.

DistanceToAdjust

Set the tolerance distance.

RebuildMesh

Strips texture coordinate, vertex colors, surface curvatures and surface parameters from a mesh and recreates only the face and vertex normals, which helps clean up, repair, and close mesh files for rapid prototype printing.

Vertices and faces are kept. Face normals and vertex normals are recalculated. Texture coordinates, vertex colors, surface curvatures, and surfaces parameters are not replaced. Use this command to rebuild meshes that are not acting properly.

Steps:

• Select mesh objects.

RebuildMeshNormals

Removes mesh normals and reconstructs the face and vertex normals based on the orientation of the faces, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh objects.

ReduceMesh

Reduces the number of polygons in a polygon mesh and converts mesh quadrangles to triangles.

Steps:

1. Select mesh objects.

2. Set the new polygon count.

3. To see the results of the reduction, click Preview.

Notes

• If the mesh has quadrangles in it, the count of starting triangles is the number of triangles after all of the quadrangles are split. Only triangles can be made in the new mesh, so it is possible to reduce the mesh and have more faces than you started with.

• It is possible to end up with meshes whose edges are shared by more than two faces (non-manifold), which may be undesirable in some cases. For one thing, this makes it hard to tell where the inside is.

-ReduceMesh

DeleteMeshFaces

Removes selected mesh faces from the parent mesh creating a hole, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select mesh faces.

Note: This command is most effective in a shaded display mode since then the user can pick within a shaded mesh facet to select it.

SwapMeshEdge

Transposes the corners of mesh triangles that share an edge, which helps clean up, repair, and close mesh files for rapid prototype printing. The edge must be shared by two faces.

Steps:

• Select a shared mesh edge.

Note: Mesh edges and other subparts cannot be selected in a shaded view.

MatchMeshEdge

Moves face edges of an open mesh to meet adjacent face edges exactly so the mesh will be closed, which helps clean up, repair, and close mesh files for rapid prototype printing.

First, the command will try to match vertices, then it will try to split edges to make the edges match. No part of the mesh is moved more than the specified tolerance.

You can use this command either on the complete mesh or on selected edges.

When selecting a whole mesh, using a high tolerance can create unexpected results. Use larger tolerances only if you select specific edges to close.

Before edge matching, magenta edges are open. The size of the fillet is labeled.

Steps:

• Select a mesh edge.

Options

PickEdges

Select specific edges to match.

DistanceToAdjust

Set the tolerance distance.

RatchetMode

If Yes, matching the mesh takes place in four passes starting at a tolerance that is smaller than your specified tolerance and working up to the specified tolerance with successive passes. This matches small edges first and works up to larger edges.

SplitDisjointMesh

Divides into separate mesh objects meshes that do not connect, but are still one object, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

• Select a mesh.

A mesh object has the ability to appear to be separate objects while still belonging to the same mesh.

This can happen due to mesh editing or by importing a mesh in this condition.

SplitMeshEdge

Divides a mesh edge to create two or more triangles, which helps clean up, repair, and close mesh files for rapid prototype printing.

Steps:

1. Select a mesh edge.

2. Pick a location for the split.

Use the SplitMeshEdge command to specify how you want to split faces, and then match an adjacent mesh using the MatchMeshEdge command.

ThicknessAnalysis

Uses a false-color display to evaluate the distances between two surfaces.

Steps:

• Type the minimum or maximum acceptable thickness.

Example:

The thickness analysis dialog box has a range of values.

Blue = B; Red = R

Assume 0 < R < B.

For each analysis mesh vertex V, Rhino searches for a point P on "the other side".

d = the distance from P to V.

If d <= R, the vertex V is red.  

If d > B, the vertex is white.  

If R <= d <= B, the vertex is the appropriate color in the range from red to blue.

The percentage reported is the percentage of analysis mesh vertices that are not white. In this example, it is the percentage of the analysis mesh vertices whose distance to the "other side" point is <= B.

ThicknessAnalysisOff

Turns the false color thickness analysis display off.