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 accuracy, transparency, and colour of the Solid.

Note: SolidWorks 2018 SP1: Bug : Model does not import in the correct orientation, even with a Coordinate-System.

See Also: Model (or Mechanism) Editor dialog-box | Synchronize tab

YouTube Tutorial:




tog_minus Import from SOLIDWORKS 


Often, you need to use button 2s [then WAIT] and then button 12s.
To see the model in Mechanism-Editors you must use Visibility toolbar > Show Model in Mechanism


MUST DO STEP 1: Read button 2s

1.Click the Read button, and wait, to read the active SolidWorks® document:
path and file-name [see box: 4s ]
configuration [see box 7s ]


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 [Read-Only]The SolidWorks® file-name, with its full path
SolidWorks Configuration5s[Read-Only]: The name of the active SolidWorks configuration
Current Model Status6s [Read-Only]:
Out of Date: if the date/time of the file in box3s in 'disk memory' is older than the current date/time.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 imported model.

MUST DO STEP 2: 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 onto the CAD-Line.

The name of the STL File is:

Document Name-Configuration Name.STL

[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.]

Rename CAD-Line to SolidWorks Part name 11s


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 'Show Solids in Mechanism' to view the Solid model in a Mechanism-Editor.


Drag the Slider to change the Transparency.


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 


When do you need to import import STL files?

When you do not have SolidWorks.
You only have an STL file.

To import an STL file onto the CAD-Line

1.Browse button:
Click to browse to and select an STL file (Binary)
2.Import STL File Button:
Click to import the STL file onto the CAD-Line.
3.Edge Angle Limits:
Experiment to improve the quality of the STL file in the MechDesigner model.


Example results from Edge Angle Limit parameter.

We use the Edge Angle Limit parameter to remove 'edges' from the facets of the STL Part.

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

For example:

you do want to show the edge 'lines' at a 'square' corner.
you do not want to show the edge of each facet around a circular shaft.

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.





When you import a SolidWorks model, we instruct MechDesigner to save the model as .STL file-type, then we import the .STL file.

A large STL file will slow down the speed MechDesigner, and thus it is important to understand the parameters that make the STL file larger.

STL Files

The STL file renders the surfaces of the CAD model as a mesh of 'triangles, in a process called 'tessellation'. The number of triangles determines the accuracy of the tessellated STL file when compared to the original CAD model.

Chordal Tolerance / Deviation:

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

The maximum distance is 0.5mm.

Angle Control:

The angular deviation allowed between adjacent triangles.

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

The maximum angle is 30º.

STL File Format:

Make sure the STL file is saved in the Binary format.

Binary files are smaller by a factor of 6!. MechDesigner can only import Binary STL files!


Make sure the units are set to meters in your CAD model.

Coordinate Systems:

We do not recognize the Coordinate System in an STL file.

Make sure the original STL is at the correct place and orientation:

Move the CAD part so that its Origin and the X– and Y–axes of the part will coincide with Origin and the X- and Y–axes of the CAD-Line in MechDesigner. This makes the +Z-axis point towards you in the front XY View.
Move the CAD part along the Z-Axis, as needed, to offset the Solid relative to the Mechanism Plane.

STL Geometry Check:

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

To reduce STL file size, and so make MechDesigner more responsive after you import the file, create a new configuration. 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.


1.To import more Solids onto one Part
a.Add new CAD-Lines to the Part
b.Import each SOLIDWORKS Part model onto each new CAD-Line.
2.To remember which CAD-Line is for which SOLIDWORKS Part, rename the CAD-Line to the SOLIDWORKS Part-Name - see the Rename button.
3.If you email a Model, then email the .ZXL file.  All the files you use in the model are in in the .ZXL file
4.Create a new configuration in SolidWorks for the document you will import to MechDesigner.
5.In the SOLIDWORKS model, remove or suspend Fillets, or replace them with chamfers. STL files with Chamfer are much smaller than the similar file with Fillets

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