Convert SLDPRT to SLT

A 3D printer or slicer normally requires an .stl mesh, while SolidWorks parts use the native .sldprt format. The extension .slt is not a general-purpose CAD replacement, so confirm the target software’s required format before exporting.

What the SLDPRT format is

.sldprt is SolidWorks’ native part format. It can contain sketches, dimensions, feature history, configurations, materials, reference geometry, and one or more solid bodies. SolidWorks users create and edit these files for mechanical design, manufacturing, simulation, and 3D printing.

Other CAD applications may import SLDPRT files through translators, but compatibility depends on the application, SolidWorks version, file features, and sometimes the translator license. An SLDPRT file is not a suitable direct input for most slicers because it contains parametric CAD data rather than a triangular print mesh.

What the SLT format is

There is no broadly standardized, general-purpose 3D exchange format identified by the .slt extension. Conversion requests using “SLT” commonly mean STL, the stereolithography mesh format. Some programs may assign .slt to a proprietary format unrelated to SolidWorks or 3D printing.

STL stores a surface as triangular facets and is accepted by most 3D-printer slicers, rapid-prototyping systems, and mesh tools. It does not retain SolidWorks sketches, dimensions, feature history, configurations, materials, assembly relationships, or editable parametric design intent.

How to export an SLDPRT file to STL

If the receiving program explicitly requires .slt, use that program’s documented exporter or a converter from the same vendor. Do not rename .sldprt to .slt; changing the extension does not convert the file.

For the usual SLDPRT-to-STL case, SolidWorks provides the most direct desktop workflow:

1. Open the part and activate the required configuration. Check that the intended bodies and features are visible.
2. Select File → Save As.
3. Set Save as type to STL (*.stl).
4. Open Options and select the units expected by the slicer or manufacturing system.
5. Choose Fine for a general export, or choose Custom to specify deviation (chord height) and angle tolerance. Smaller tolerances create a more accurate but larger mesh.
6. Save the file, then open it in the slicer or mesh checker. Verify scale, orientation, closed surfaces, and any gaps before manufacturing.

For batch processing, SolidWorks can export STL through its API or macros, with the exact code and tessellation settings varying by SolidWorks release. CAD Exchanger Desktop and CAD Exchanger Cloud can also translate supported SLDPRT files to STL; verify current SLDPRT input support and output settings before relying on either service. Cloud conversion uploads the design to a third party, so it is unsuitable for confidential, restricted, or export-controlled parts unless the organization has approved that service.

Quality and compatibility limitations

STL is a tessellation: curved CAD faces become triangles. Coarse deviation or angle settings can create visible faceting and inaccurate dimensions. Excessively fine settings produce larger files and slower slicing without improving results beyond the printer, nozzle, or manufacturing process resolution.

STL files are commonly treated as unitless. Select the same unit system in SolidWorks and the receiving application, then verify a known dimension after import. A unit mismatch can make the model appear 25.4 times too large or too small.

The export can be affected by the active configuration, suppressed features, hidden or excluded bodies, and invalid geometry. Inspect the exported mesh rather than assuming it represents every object in the part. Use the slicer’s repair function or a mesh checker such as Microsoft 3D Builder or Autodesk Netfabb to detect holes, inverted normals, self-intersections, and non-manifold edges.

For editable CAD exchange, use .step or .iges instead of STL. STEP and IGES preserve surfaces and solids more effectively, but they still do not preserve the original SolidWorks feature tree and may require healing after import.