MechDesigner Reference & User Interface > Dialogs

To import an STL file:

STL file Import

1.Click the Browse button

2.Explore and select an STL file

3.Click the Import button.

Note: To see the CAD-Solid, enable Visibility toolbar > Show Solids in Mechanisms

Edge Angle Limit

1.Enter a Value in the Edge-Angle Limit box

This parameter can change the apparent quality of the STL file in the graphics-area.

Edge Angle Limit analyzes the acute angle between two adjacent facets of the STL file that represents the Part/Assembly document

•If the acute angle between two adjacent faces is less than(<) the Edge Angle Limit, we do not show a line at the edge of the two facets.

•If the acute angle between two adjacent faces is greater than (>) the Edge Angle limit, we do show a line at the edge of the two facets.

See Top-Tip.

Solid Color button - to edit the color of the STL file:

1.Click the Solid Color button

2.Select a color in the Windows Color Picker®

3.Click OK in the Windows Color Picker®

STL File Units

1.Select the units to equal the units of the original STL file.

Try meters, [m], if you are not sure.

Top-Tip

I find these options are a good compromise of display quality, display accuracy, and STL file-size.

Edge Angle Limit =80 (STL Import tab)

Linear Deviation = 0.04 (SOLIDWORKS tab)

Angular Deviation =30 (SOLIDWORKS tab)

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 appears as a small face - which we call a facet. The number of facets is a function of:

•the complexity of the original CAD 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 STL file,

... AND each STL file to appear as the original CAD model,

... AND to see only those facets that define real edges in the CAD model.

Strategy 1: Reduce the complexity of the original CAD Model to reduce the STL file-size

Add a new configuration for the CAD model. In the new configuration:

•Do a geometry check to find if it has any small gaps or whiskers

•Suspend external fillets and internal fillets, especially if they do not have a function

•Replace fillets with chamfers if functional

•Suspend all fasteners

•Suspend fastener holes and hole features

•Suspend all cosmetic details

•Replace complex models you may have downloaded from the internet with simplified models, e.g. bearings.

Strategy 2: Reduce the accuracy of the STL file

There parameters are in the CAD-Line > 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, find these parameters in your 3D-CAD before you save your model as the STL file. It is possible Linear and angular deviation are options in the Save as > STL file-type dialog.

Strategy 3: Use the Edge Angle Limit parameter - see Import STL File above

STL files will show their facets if the angle in Edge Angle Limit is less than the facet of the CAD-Solid. Experiment. Import the model again each time you edit Edge Angle Limit (try 80 degrees).

Examples

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: Large number of Vertices

BAD - many facets

•Linear Deviation = 0.014mm and

•Angular Deviation = 0.4º

There are

•119132 vertices

•~40000 triangles

•The STL file size is 3.5 Mega Bytes

STL: Few number of Vertices

GOOD - few facets

•Linear Deviation = 0.5mm and

•Angular Deviation = 5º

There are:

•7533 vertices

•~2500 triangles

•The STL file size is 0.365 Mega Bytes

-> STL Import tab

-> STL Import tab

CAD-Line > STL Import tab

CAD-Line dialog

STL Import tab

STL Files