See also : CAD-Line dialog-box
Before you save the 3D-CAD model as an STL file:
•Rotate the 3D-CAD model (in your 3D-CAD) to put its Front-Plane parallel with the XY-Plane of the Mechanism-Editor in MechDesigner.
If you cannot easily rotate the CAD-model in you 3D-CAD as a Part, then
1.Create an assemble, add the Part, and
2.Rotate the Part in the Assembly. Then
3.Save the Assembly as a Part. Not ideal, but a method.
See also : Display Options to move the STL file after you import it, along the X, Y, and Z-axes in MechDesigner.
•To reduce the complexity of the STL file, remove fillets (and rounds) and other details that you do not need to see in MechDesigner.
In the dialog to save the CAD model as STL file-type:
•Set the STL file-type as Binary
•Make a note of the Linear Units
Use STL Import to:
•Set the Linear Units to equal those Linear-Units of the original STL file
•Import one STL file - it becomes a CAD Solid in MechDesigner
•Edit the Edge Limit to remove 'facet lines'.
STL file Import- to import an STL file
1.Click the Browse button
2.Explore and select an STL file
3.Click the Import STL File button:
Look at the model in MechDesigner.
To see the model in Mechanism-Editors, you must use Visibility toolbar > Show Model in Mechanism
Solid Color button- to edit the color of the STL file in the graphic-area:
1.Click the button Browse button
2.Select a color in the Windows Color Picker®
3.Click OK in the Windows Color Picker®
STL File Units
Select the units that are equal to the units of the Original STL file
Edge Angle Limit - to change the apparent quality of the STL file in the graphic-area.
The Edge Angle Limit parameter analyzes the acute angle between two adjacent facets in the STL file.
If the angle between two adjacent facets in the STL file is less than Edge Angle Limit, we do not show a line between the two facets.
If the angle between two adjacent facets in the STL file is greater than the Edge Angle limit parameter, we do show a line at angle made by the two facets.
Magic Number for Edge Angle Limit to remove edge lines.
Edge-Angle Limit = Angular Deviation × Π ÷ 2
E.g. compare the top image, to the left, with the bottom image.
Angular Deviation = 8º
•In the top image the Edge Angle Limit parameter = 8º.
•In the bottom image the Edge Angle Limit parameter = 8 × Π ÷ 2 = 12.56637º.
See Angular deviation parameter.
The STL file tessellates the surfaces of the CAD model as a mesh of triangles. Each triangle can appear as a facet. The number of triangles is a function of:
•the complexity of the original model, and
•how accurately you want the STL file to tessellate the original CAD model.
To build complex models, and import many STL files, you want a:
•Small STL file-size
•AND it to appear as the original CAD model,
•AND not to see the tessellation / facets
Strategies to reduce the STL file-size.
Strategy 1: Reduce the complexity of the original CAD Model.
Add a new configuration of the CAD model. In the new configuration:
•Do a geometry check of the CAD model file to find if it has any small gaps or whiskers.
•Suspend small fillets, especially if they do not have a function.
•Replace fillets with chamfers, if possible, especially along straight edges.
•Suspend all fasteners
•Suspend fastener holes and hole features.
•Suspend all cosmetic details.
Strategy 2: Reduce the accuracy of the STL file
There are two parameters to control the accuracy of the STL file:
If you do not have SolidWorks, you must find these parameters in your 3D-CAD before you save to the STL file. It is possible they are options in the Save as STL file-type dialog.
Linear Deviation :
The maximum chordal deviation (distance) between the surface of the original CAD model and the tessellated surface of the STL file.
E.g. See SolidWorks tab | Import from SolidWorks : Maximum Linear Deviation is 0.04mm.
Angular Deviation :
The maximum angular deviation between adjacent facets of the tessellated surface of the STL file.
E.g. See SolidWorks tab | Import from SolidWorks Maximum Angular Deviation is 23º.
Strategy 3: Use the Edge Angle Limit parameter - see STL File Import above
Small STL files may show their facets. You can improve how the facets display with my Magic Number!
Edge Angle Limit = Angular Deviation × Π ÷2
STL tessellation: Large number of Vertices
BAD - too many facets
•Linear Deviation = 0.00762083mm and
•Angular Deviation = 0.5º
•The STL file size is 79.3 M-Bytes
STL tessellation: Few number of Verticies
GOOD - very few facets
•Linear Deviation = 0.1829mm and
•Angular Deviation = 30º
•The STL file size is 184 k-Bytes
There is very little difference to the view of the Solid.