Tutorial 19: Import SOLIDWORKS Part and Assemblies

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Tutorial 19: Import SOLIDWORKS Part and Assemblies

How to prepare and import SOLIDWORKS Parts and Assemblies

We use the CAD-Line dialog-box | SolidWorks tab to import SOLIDWORKS Part and Assembly documents.

In MD14 and later, we check with your Windows Registry which SOLIDWORKS release you used last. We then install the correct Type-Library automatically. If, at any time later, you use a different SOLIDWORKS release, you only need to restart MechDesigner.

You can check that the Type-Library is correct: see Help menu > About > Type-Library tab.

Coordinate System in MechDesigner

CAD-Lines

CAD-Lines

COORDINATE-SYSTEM IN MECHDESIGNER

CAD-Lines:

Edit a CAD-Line to import a CAD Solid (SolidWorks or STL), and/or a DXF file.

There is one CAD-Line along the center of each Part that you add to the model.

To import more CAD Solids onto the same Part : edit the Part, and do Geometry toolbar > Add CAD-Line.

ALL CAD-Lines have a Coordinate-System

•Origin: start-Point of the CAD-Line

•+X–axis: from start-Point to end-Point

•+Y–axis: is +90º from +X–axis and on the Mechanism Plane

•+Z–axis: normal(⊥) to the Mechanism Plane.

Coordinate System in SOLIDWORKS

All SOLIDWORKS CAD documents have a Coordinate System.

However, usually, you must add a Coordinate System feature to the SOLIDWORKS document to indicate how you want to align it with the CAD-Line in MechDesigner.

The Origin and X-axis of the Coordinate-System in SOLIDWORKS will coincide with the start-Point and end-Point of the CAD-Line in in MechDesigner.

The image below shows a SOLIDWORKS document with a Coordinate System feature.
SOLIDWORKS CAD model prepared for import to MechDesigner

SOLIDWORKS CAD model prepared for import to MechDesigner

To add a Coordinate System, we must select a Point or Vertex, and a Line or Edge. Rather than select from the model's existing features, I usually add a new Plane and sketch to the model. I can edit the new features if I want, later.

I usually do these steps:

1.Add a new PlaneRed-14-1b

SOLIDWORKS > Insert menu > Reference Geometry > Reference Plane

It becomes the XY-Plane of the Coordinate System. It will be coplanar with the Mechanism-Plane in MechDesigner.

2.Start a new SketchRed-14-2 on the new PlaneRed-14-1b

Add two perpendicular construction lines.

The lines should intersect where we want the model to coincide with the start-Point of the CAD-Line.

Close the sketch.
Add Coordinate Syastem dialog in SOLIDWORKS

Add Coordinate Syastem dialog in SOLIDWORKS

3.Add the Coordinate SystemRed-14-3  

SOLIDWORKS > Insert menu > Reference Geometry > Coordinate System

a.Click the point at the intersection of the construction lines as the Origin

b.Click the construction line that is the +X-axis

c.Click the construction line that is the +Y–axis.

The +Z–axis should be towards you, the same as the +Z–axis direction of the CAD-Line in MechDesigner.

Procedures to Import SOLIDWORKS Documents

SOLIDWORKS: Add a Coordinate System to the SOLIDWORKS document.

See above : To add a Coordinate System in SOLIDWORKS

MechDesigner:

Make sure there is an active document open in SolidWorks®

As a minimum, you must do:

STEP 1: Click the ReadRed-14-2 button and, WAIT

STEP 2: Click the ImportRed-14-12 button and WAIT

The other buttons are optional.

Do Visibility toolbar > Show Solids in Mechanism to see the SOLIDWORKS document in the Mechanism-Editor as soon as you import it.

CAD-Line dialog > SOLIDWORKS tab

CAD-Line dialog > SOLIDWORKS tab

STEP 1: Click the ReadRed-14-2 button

WAIT until the

•SolidWorks® Part/Assembly (read-only) shows in boxRed-14-4

•SolidWorks Configuration (read-only) shows in boxRed-14-5

•Current Model Status (read-only) shows in boxRed-14-6

Unavailable - before you import SolidWorks® document the first time.

Out of Date - the file in boxRed-14-4 is older than the current date/time.

Up to Date - the date/time of file in boxRed-14-4 is the equal to the date/time when imported.

If necessary:

•Select the SolidWorks Coordinate-SystemRed-14-8

STEP 2: Click the Import Red-14-12 Button

Wait - a large model can take time to import.

Optional Buttons(Red-14-1bRed-14-3)

ButtonRed-14-1b : Remove : SolidWorks® documentRed-14-4 from the CAD-Line

ButtonRed-14-3 : OPEN : SolidWorks® documentRed-14-4 in SolidWorks

ButtonRed-14-11 : Rename CAD-Line to SolidWorks document file-name.

Notes on CAD-Solid File Quality Red-14-10a

○ Fine: more vertices

○ Coarse: fewer vertices

○ Custom : edit Linear Deviation/Angular Deviation

•Linear DeviationRed-14-7: Maximum =0.5mm; Minimum =0.014mm

•Angular DeviationRed-14-9: Maximum =30º; Minimum =0.4º

WARNING : Number-of-Vertices increase rapidly as you reduce the Linear/Angular Deviation.

Also, the CAD-Solid may not appear to improve! See : Edge Angle Limit parameter.

If the sub-assembly has many parts and features that you do not need to see in the MechDesigner model  - for example washers, screws... - then in SOLIDWORKS, create a new Configuration.

In the new SOLIDWORKS configuration, suppress parts and features that you do not need to see. Also, suppress fillets, or replace with chamfers, where possible.

SOLIDWORKS:

1.Make active the configuration in which you have suppressed parts and features.

2.Add a Plane and Coordinate System, ... - see Procedure 1: above

MechDesigner

See Procedure 1 above

To import more than one SOLIDWORKS document onto one MechDesigner Part, you must use the Psrt-Editor to add to it more CAD-Lines.

PREPARATION

SOLIDWORKS:

1.At the top level of the assembly: add a Plane. We might call this the Master Plane. Drag it to the top of the Assembly Feature-Manager, if possible.

In the assembly, Edit Parts in Context - that is, do not leave the SolidWorks assembly to edit each part.

2.Edit Part A in Context:

a.Add a Plane, and make it coplanar with the Master Plane

b.Add a sketch to the new Plane, and then add the Coordinate System.

c. Close Edit Part in Context

3.Do 2 for each Part in the Assembly - ALL COORDINATE SYSTEMS SHOULD BE COINCIDENT.

MechDesigner:

4.Edit a Part and add CAD-Lines  equal to the number of documents/parts you will import from SOLIDWORKS onto the one Part.

5.Make the start-Point of all of the new CAD-Lines coincident with the origin of the Part, and make each CAD-Line collinear with X-axis.

IMPORT EACH PART:

SOLIDWORKS:

1.Open a SOLIDWORKS Part.

The Plane, sketch and Coordinate-System should be a feature in the Part.

The Part is now the active document in SOLIDWORKS.

MechDesigner:

2.Edit each CAD-Line: and import the SOLIDWORKS Part.

3.Rename each CAD-Line to the same as each SOLIDWORKS Part.

Do 1-3 for each SOLIDWORKS Part you want to import.

All of the XY-Planes in each Coordinate-System should be coplanar.

Their Origins and X-axes do not need to be coincident, of course, as they will be imported on to different MechDesigner Parts.

Again, we use a Master-Plane in the SOLIDWORKS document.

In SOLIDWORKS

1.At the top level of the assembly, add a Plane. We can call it the Master Plane.

Move it to the top of the Assembly Feature-Manager, if possible.

In the assembly

2.Edit Part A in Context: that is, do not leave the SolidWorks assembly to edit the Part.

a.Add a Plane, and make it coplanar with the Master Plane

Do 2 for each SOLIDWORKS part you want to import to MechDesigner.

3.Open each Part

a.Add a sketch to the Plane in each Part, and then a Coordinate System.

b.Make sure each Coordinate System will align with the CAD-Line in each MechDesigner Part.

Do 3 for each part you want to import.

In MechDesigner:

1.Make sure the correct document is the active document in SOLIDWORKS.

2.Edit a CAD-Line: and import the SOLIDWORKS Part.

3.Rename the CAD-Line to the same as the SOLIDWORKS Part.

Do 1-3 with each CAD-Line and SOLIDWORKS Part.
btn_delkeyword Import STL Files directly

When do you need to import STL file-types?

•When you do not have SOLIDWORKS.

•You can save a model as the STL file-type in your CAD software.

Notes: in your CAD software:

•Save as a STL file in the Binary Format

•The STL file-type does not use a Coordinate System.

Thus, before you save the STL file:

oMove the original CAD part so that its Front-View is the same as the Front-View of the Mechanism-Editor.

Note: It is possible to move the STL part in the X, Y, Z-axis directions, but not rotate the model - see below

GST-Dialog-CADLine-SW-STL

GST-CAD-EdgeLine

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.

Edge Angle Limit parameter and STL files.

We use the Edge Angle Limit parameter to remove 'ghost 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'.

The Edge-Angle-Limit parameter value is a function of the Linear Deviation and Angular Deviation parameters in the 'Model Import from SOLIDWORKS' separator.

Magic Number for Edge Angle Limit to removed unwanted edges from facets.

Enter Edge-Angle Limit = Angular Deviation (Actual Value) * 3.14159/ 2

Compare the top image, to the left, with the bottom image.
GST-CAD-EdgeLine-NoEdges
btn_delkeywordSTL: FILE-SIZE and APPEARANCE

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 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 facets

Strategies to reduce the STL file-size.

Strategy 1:

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.

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

STL tessellation: Large number of Vertices

Example

BAD - too many facets

•Linear Deviation = 0.014 and

•Angular Deviation = 0.4º

There are

•119132 vertices

•~40000 triangles

•The STL file size is 3.5 Mega Bytes
STL tessellation: Few number of Verticies

STL tessellation: Few number of Verticies

GOOD - very 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

 

There is very little difference in the representation of the Solid.