Standard Tessellation Language (STL) files represent a 3D surface as a set of triangular facets and are commonly used for 3D printing and additive manufacturing. When exporting a CAD model to an STL file, it is important to balance the triangle count and file size by adjusting the resolution settings. A higher resolution with more triangles provides more detail but a larger file, while too low a resolution risks losing important surface details in the 3D printed part. Proper STL export settings depend on the complexity of the model surfaces and size.

1. EXPORTING
TO STL
WHAT IS AN STL FILE FORMAT AND HOW
WE CAN CONVERT OUR CAD INTO STL
Greta D’Angelo
Martí Bertran
Thomas J. Howard

2. STL FILES
• Standard format for AM production
• Triangular mesh representation of a 3D surface geometry
• More triangles  higher definition
• Find the compromise between the definition and the lowest
possible file size  High sized files may not be processed
by the Gcode generator software
• Adding more triangles doesn't mean to obtain a more
accurate built part, because the definition that can give the
machine may be not as high
“Standard Tessellation Language (STL) file is a triangular representation of a 3D surface geometry. The surface is tessellated
logically into a set of oriented triangles (facets). Each facet is described by the unit outward normal and three points listed in
counterclockwise order representing the vertices of the triangle. While the aspect ratio and orientation of individual facets is governed
by the surface curvature, the size of the facets is driven by the tolerance controlling the quality of the surface representation in terms
of the distance of the facets from the surface. The choice of the tolerance is strongly dependent on the target application of the
produced STL file. In industrial processing, where stereo lithography machines perform a computer controlled layer by layer laser
curing of a photo-sensitive resin, the tolerance may be in order of 0.1 mm to make the produced 3D part precise with highly worked
out details. However much larger values are typically used in pre-production STL prototypes, for example for visualization purposes.”

3. EXPORTING STL FROM
SOLIDWORKS
The orientation of the building platform is the XY plane
(FRONT PLANE in solidworks)
Steps:
• Click “Save as”
• In “Save as type” list select: “STL (*.stl)”
• Click “Options”
• Output: Binary
• Unit: Millimetres
• Resolution: Custom
• Deviation: 0,02 - 0,05
• Angle: 15º - 20º
“Deviation and angle default values for “Coarse” and “Fine” depends on the
surfaces and size of the model we want to export, the optimised values will always
3 be between these two values.”

4. EXPORTING STL FROM
SOLIDWORKS
Steps for Solidworks Student Design Kit
• File  Save As …
• Set type to “eDrawings(*.eprt)”
• Click “Options...”
• Enable “Allow export to STL for Parts & Assemblies”
• Click OK
• Enter Filename  Save
• Open part in Solidworks eDrawings
• File  Save as…  select type STL Files (*.stl)
• Save
“With this way, you can’t choose the resolution of the output STL file, and it’s not
the best. So avoid this system if your model has characteristic curved surfaces.
Solidworks Edition on DTU Databar PC’s let you to export direcly to STL from
4 solidworks. So only use that method if you have the Student design kit.”

5. EXPORTING STL FROM
SOLIDWORKS
“When exporting from an assembly, make sure you have ”Save all components of an
assembly in a single file” is DISABLED, and all the components will be saved individually.”

6. SOLIDWORKS DESIGNING TIPS
“Always check ”Merge result” is enabled when doing new features. IF this option is
disabled, the new features created will be new ”bodies” in our part, and we don’t wont
that.”

7. SOLIDWORKS DESIGNING TIPS
“Before exporting to STL, you should have only one ”body” in your part. If, like is shown
in the pic above, you have more than one, that may mean that you have been creating
new features with the option ”merge result” disabled.”

8. EXPORTING STL FROM
PTC CREO (PRO/E)
Steps:
• Click “Save a copy”
• In “Type” list select:
“Stereolithography (*.stl)”
• Coordinate system:
Default (TOP plane as XY)
• Format: Binary
• Deviation control
• Chord height: 0,05
• Angle control: 0,5
“You can see the output triangulated mesh when you click on “Apply”. Optimum values
depend on the size and surfaces of your part, so change the values in order to get a
mesh detailed enough to have smooth surfaces, but not more.”

9. PTC CREO DESIGNING
TIPS
“Enable ”Extrude as Solid” and ”Attached” when creating new features to our model.”
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