Terminology: Solids, CAD-Line

Use the CAD-Line dialog-box | SolidWorks tab to:

1.Import a SolidWorks® Part or Assembly
2.Import an STL file
3.Show or hide the Solid, change its accuracy, transparency, and colour.


Edit a Part to add extra CAD-Lines; import a different SolidWorks / STL model on to each CAD-Line.





tog_minus Import from SOLIDWORKS 


You will most often use ONLY two buttons: Read button2s [then WAIT] and then Import button12s.
To see the model in Mechanism-Editors you must use Visibility toolbar > Show Model in Mechanism



Read button 2s

1.Click the Read button2s, and wait, to read the active SolidWorks® document:
Path and file-name - see box: 4s
Configuration - see box 5s
Coordinate System - see box 8s


When a SolidWorks CAD file is in box4s, you can use:

1.Remove button1s-red: to remove the CAD model from the CAD-Line and box4s
2.Open button3s: to open in SolidWorks the file that is in box 4s .


SolidWorks Part / Assembly 4s The SolidWorks® file-name, with its full path
SolidWorks Configuration5s: The name of the active SolidWorks configuration
Current Model Status6s
Out of Date: if the date/time of the file in box3s in 'disk memory' is older than the current date/time.
Up to Date: if the date/time of the file in box3s is the same as the date/time of the File saved to disk.


File Quality 10s - To control the linear and angular fidelity of the imported document

Fine: more vertices - [default]
Coarse: fewer vertices
Custom :  'Custom' must be active to edit the Linear Deviation and Angular Deviation parameters.
Linear Deviation7s: Maximum =0.5mm; Minimum =0.014mm
Angular Deviation9s14: Maximum =30º; Minimum =0.4º

Coordinate System8s: Use when there is more than one Coordinate System in the SolidWorks document.


Import Model button 12s

2.Click to import the SolidWorks document3s onto the CAD-Line.

MechDesigner saves the document as an STL file and then imports that STL file onto the CAD-Line.

The name of the STL File is: Document Name-Configuration Name.STL

Optional Button: Rename CAD-Line to SolidWorks Part name 11s

[Top tip: if you hover above the box4s, the full path and file-name shows as a tool-tip, and in the 'Extended Hints' box. After 3 seconds, the full file name disappears as a tool-tip, but not from the extended hints box.]



1.Tile SolidWorks and MechDesigner before you use the Import button - you need to see any messages that may show in SolidWorks.
Pop-up in SolidWorks

Pop-up in SolidWorks

For example:

1.A large file can take some time to import - be patient! Wait until a number shows in the Number-of-vertices box (see Display Options separator), before you click OK
2.Some files that you download from the internet are huge. Try to reduce their size before you import it.
3.Chamfers use fewer vertices than Fillets. Always suspend Fillets in the SOLIDWORKS file
4.Cosmetic Threads in CAD add a may vertices - Suspend them

tog_minus Display Options 

Dialog-CADLine-SW-Display Options

Show / Hide the Model

1.Click the check box to show the Solid that you have imported onto the CAD-Line.

You must also use 'Visibility toolbar > Show Solids in Mechanism to view the Solid model in a Mechanism-Editor.


Drag the Slider to change the Transparency. Experiment!

Solid colour:

Click the Solid colour button to open the Windows® colour picker

Number of Vertices: [Read only]

Complex files have more vertices. MechDesigner is slower when the Number-of-Vertices is very high.

How many is too many? It depends on your PC.

Experiment with the Fine, Coarse and Custom radio buttons in the 'Model import from SolidWorks' separator.

Try to make Number-of-Vertices < 20,000.

Top Tips: Make a new SOLIDWORKS Configuration if there are many features that add vertices for cosmetic reasons.

In the new configuration, reduce the number of vertices:

Remove Fillets, cosmetic fillets.
Use Chamfers to show model edges.
Do not import models with balls in ball bearings!
Make the model as simple as possible.

tog_minus STL File Import 

Import an STL file.


Save the STL file in Binary Format and in SI meters
The STL file cannot use a Coordinate System.

Before you save the original CAD part as an STL file:

oMove the original CAD part so that its Origin, X–axis, and Y–axis coincide with the Origin,  X-axis, and Y–axis of the CAD-Line in MechDesigner.
oMove the original CAD part along the Z-Axis, to move it relative to the Mechanism-Plane in MechDesigner



When do you need to import import STL files?

When you do not have SolidWorks.
You have or can save a model as an STL file.

To import an STL file onto the CAD-Line:

CAD-Line dialog > SolidWorks tab > STL file import separator:

1.Click the Browse button
2.Select an STL file (Binary)
3.Click the Import STL File Button:

Look at the model in MechDesigner. If there are too have many 'edges', increase the:

4.Increase the Edge Angle Limit parameter - see more below...
5.Re-import the STL file

Edge Angle Limit parameter and STL files.

We use the Edge Angle Limit parameter to remove 'edges' from facets in the STL file.

If the angle between a facet in the STL file is less than the Edge Angle Limit parameter, then we do not show an 'edge'.

Compare the top image, to the left, with the bottom image.

In the top image the Edge Limit Angle parameter is set to 6º.
In the top image the Edge Limit Angle parameter is set to 26º.




Large STL files make MechDesigner less responsive. Thus, it is helpful to understand the parameters that make STL files large or small.

STL files render the surfaces of CAD models as a mesh of triangles, in a process called 'tessellation'. The number of triangles determine the accuracy of the STL file when compared to the original free-form CAD model.

The complexity of the original model and its tessellation accuracy determines the STL file size and ultimately how responsive is MechDesigner.

When you import many STL files, or the files are complex, or both, then MechDesigner can become less responsive in the graphic-area.

You can employ two strategies to reduce the STL file size and keep MechDesigner is responsive.

Reduce the Complexity of the Original CAD Model

Model designs containing 'holes', 'gaps' and 'whiskers' adversely affect the quality of the model. Therefore, you should perform a geometry check of the model files before saving to STL.

Reduce STL file size, create a new configuration of the model in your CAD. In the new configuration:

Delete, or suspend, small fillets, especially if they do not have a real function.
Replace fillets with chamfers, if possible.
Remove all fasteners
Delete fastener holes and hole features.
Remove cosmetic details.

Reduce the accuracy with which you save the STL file

We instruct SolidWorks to save the model as an STL file, which we then import with MechDesigner.

We use two parameters in MechDesigner to control the accuracy and thus size, of the STL file:

Chordal Deviation:


The maximum distance between the surface of the original CAD model and the tessellated surface of the STL triangle.

In Import from SolidWorks above : Maximum Chordal Deviation is 0.5mm.

Angle Deviation:


The angular deviation allowed between adjacent triangles.

This setting enables you to increase tessellation for surfaces with small radii.

In Import from SolidWorks above : Maximum Angular Deviation is 30º.

If you save the model as an STL file from other CAD, then look for Angular, Linear or Chordal Deviation parameters, or similar options, before you save the STL file.

Tutorial and Reference Help Files for MechDesigner and MotionDesigner 13.2 + © Machine, Mechanism, Motion and Cam Design Software by PSMotion Ltd