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SOLIDCast UNIT 9: Importing STL Files

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The primary method for importing three-dimensional CAD data into SOLIDCast is through the use of STL files. STL files were originally developed for rapid prototyping (STL = STereo Lithography). They consist of a representation of the surface of a part as a series of small triangles. Most 3D CAD systems can output an STL file of a solid model.

To import an STL file into SOLIDCast, first select File… New Model. Then click on the icon that is called out as “Add a shape to the model” .

The shape selection window will appear and the STL file should be the first choice on the menu. An expanded view of the Add Shape window is given on the next page.

 

 

Now that STL file has been selected, you will see a button labeled File Click on this button and navigate to the STL file that you want to load.

When the file is selected, you will see its name appear under the File button. Note that you can select the Material type and also the shape priority before completing the import operation.

Now click on Add Shape to import the STL file.

The shape will appear in the model space, as per the following example:

 

Notes on importing STL files:

  1. An STL file can represent only ONE type of material. You cannot subdivide an STL shape into multiple pieces or materials. Therefore, if you have cores, sleeves or chills as STL shapes, each DIFFERENT MATERIAL TYPE must be contained in a different STL file, as a minimum.
  2. The Add Shape window remains active until you click on the Close button. This makes it easy to import several STL files one after the other. Navigate to a folder and load an STL file from that folder, then without closing the Add Shape window you can again press the File button to go directly to that same folder to add another STL file.
  3. There is no code in an STL file to indicate whether the file is in inches or mm. So you may need to load an STL file and view its dimensions in order to determine whether it has been properly interpreted. For example, suppose that you are working in English units. You load an STL file that you know to be about 10 inches in length. After loading and doing a Zoom Full, you switch to an orthogonal view (XY, XZ or YZ) and, by looking at the coordinates at the bottom of the screen as you move the mouse, you determine that the system thinks that this part is about 254 inches in length. This indicates that the STL file was in mm. At this point, you need to delete this shape, and re-import the file; this time, however, PRIOR TO SELECTING THE FILE, on the Add Shape Window, under the label STL File Units , click mm. The system will assume that the STL file dimensions are in mm, and they will be converted to inches as part of the import process. The opposite scenario may be true if you are in Metric units and are importing an STL file that was created in inches.
  4. There is a utility that can scale a SOLIDCast model. This may be useful to correct an error of interpretation. Suppose your system is set to English Units and you import STL files which are in mm, but do not tell the system to convert them. SOLIDCast will then interpret the dimensions as inches. Your model will then be much larger than actual size. You could user the utility program to scale the model down to the correct size (in the case, the scale factor would be 0.03937), without having to start over with the import operations. This would be quite useful if the model contained multiple STL files. For complete instructions on using this utility see Unit 46: Stand Alone Utilities.
  5. STL files may be created with different levels of tolerance. A tight tolerance results in a large file with many surface facets. These files take a long time to load and display. A looser tolerance results in fewer surface facets. These files load quickly. It is a good idea to use looser tolerances. You can estimate the number of surface facets in an STL by dividing the file size, in bytes, by 50. MOST commercial castings can be well represented with under 20,000 surface facets. Models in excess of 50,000 or 60,000 surface facets will begin to show degradation in loading and response time in the system.
  6. Some systems can produce both Binary and ASCII STL files. Use Binary files, since they are smaller and will load and edit faster than ASCII files. At the present time SOLIDCast will only recognize Binary STL files. There is, however, an ASCII to Binary STL conversion utility program included with the stand-alone utilities. See Unit 46, Stand Alone Utilities, for full instructions on using this program.
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