See also : CAD-Line dialog-box
Use this tab if you do not have SolidWorks.
Use STL Import to:
•Import one STL file - it will be a CAD-Solid in MechDesigner
•Edit the STL File Units to equal those Linear-Units of the original STL file
•Edit the Edge Angle Limit to remove facet lines.
Before you save an STL file in your CAD:
Rotate the model in your CAD to the correct orientation relative to the Mechanism-Plane before you import it.
Save the model (in your CAD software) as a Binary STL file-type.
Remember its Linear units.
After you import an STL file:
See Display Options tab to move the STL file in the X, Y, Z-axis directions.
To import an STL file:
Note: To see the model, do Visibility toolbar > Show Solids in Mechanisms
Image with too many Facet-Edges
Image with Facet-Edges OK
The STL file tessellates the surfaces of the CAD model as a mesh of triangles. Each triangle can appear as a small face - a facet. The number of facets 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 to import many STL files, you want:
•Small file-size for each model
•AND each STL file to appear as the original CAD models.
•AND not to see the facets on each STL file, or to see only those facets that define real edges in the model.
Reduce the complexity of the original CAD Model = SMALL file-size
Add a new configuration for 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, especially along straight edges.
•Suspend all fasteners
•Suspend fastener holes and hole features.
•Suspend all cosmetic details.
•Simplify bearing models, and other complex models you may have downloaded from the internet.
Reduce the accuracy of the STL file
There are two parameters to control the accuracy of the STL file. These are in the SOLIDWORKS tab.
Linear Deviation :
The maximum Linear deviation (distance) between the surface of the original CAD model and the tessellated surface of the STL file.
Angular Deviation :
The maximum angular deviation between adjacent facets of the tessellated surface 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.
Use the Edge Angle Limit parameter - see STL File Import above
STL files may show their facets. You can improve how the facets display with my Magic Number!
Edge Angle Limit = Angular Deviation × 3.14159÷2
Below, the two images are of the same SOLIDWORKS part.
They appear to be identical. However, there is a large difference in the number of facets and vertices.
STL tessellation: Large number of Vertices
BAD - many facets
•Linear Deviation = 0.014mm and
•Angular Deviation = 0.4º
•The STL file size is 3.5 Mega Bytes
STL tessellation: Few number of Vertices
GOOD - few facets
•Linear Deviation = 0.5mm and
•Angular Deviation = 5º
•The STL file size is 0.365 Mega Bytes