<< Click to Display Table of Contents >> Navigation: Getting Started Tutorials - MechDesigner > Tutorial 19: Import SOLIDWORKS Part 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. |
![]() 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. |
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. |
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![]() 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 Plane 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 Sketch 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 |
3.Add the Coordinate System 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. |
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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 |
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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. |
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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. |
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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. |
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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. |
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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. |
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Strategy 3: Use the Edge Angle Limit parameter - see STL File Import aboveSmall STL files may show their facets. You can improve how the facets display with my Magic Number! Edge Angle Limit = Angular Deviation × Π ÷2 |
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![]() 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 |
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![]() 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. |