Convert OBJ to SLDPRT

What the OBJ format is

OBJ is a text-based 3D exchange format that stores vertices, polygon faces, normals, texture coordinates, and references to materials. Blender, Maya, 3ds Max, ZBrush, MeshLab, 3D scanners, photogrammetry systems, visualization tools, and 3D-printing software commonly create or use it.

An OBJ normally represents a polygon mesh rather than a dimensioned CAD model. It can contain separate objects, holes, duplicate vertices, inverted normals, self-intersections, and non-manifold edges. The format does not reliably specify units. An accompanying .mtl file and image textures may contain appearance information, but they are separate from the geometry.

What the SLDPRT format is

.sldprt is the native part format used by Dassault Systèmes SOLIDWORKS. A part can contain sketches, reference geometry, configurations, materials, parametric dimensions, feature history, and solid or surface bodies; some SOLIDWORKS versions can also store mesh bodies.

A native feature-based part can be edited through the FeatureManager design tree and used in assemblies, drawings, simulations, and manufacturing workflows. Importing an OBJ and saving it as .sldprt does not create the sketches, constraints, features, or design intent that produced the mesh.

Convert the mesh in SOLIDWORKS

1. Make a working copy of the OBJ. Inspect and repair it in MeshLab or Blender: remove unwanted objects, merge duplicate vertices, correct normals, repair suitable holes, and reduce excessive polygon density. Keep the original file unchanged.
2. Determine the intended units and verify a known dimension. OBJ exporters commonly omit unit metadata, so an import may be scaled incorrectly even when the geometry looks correct.
3. In SOLIDWORKS, activate the licensed ScanTo3D add-in through Tools → Add-Ins when mesh preparation or surface reconstruction is required. Availability depends on the SOLIDWORKS edition and version.
4. Open the file through File → Open with OBJ selected as the file type. Choose the available mesh import mode. A mesh body or mesh BREP can provide usable geometry when the polygon count is manageable; a graphics body is reference-only and cannot be edited as a solid.
5. Use Tools → ScanTo3D → Mesh Prep Wizard, where available, to remove regions, fill appropriate holes, and prepare the mesh. Avoid filling openings that are part of the intended design.
6. For a surface-based result, use the ScanTo3D surface-reconstruction tools, then use Insert → Surface → Knit. Enable Try to form solid only when the knitted surfaces completely enclose a valid volume.
7. For a clean, editable mechanical part, use the mesh as reference geometry and remodel it with SolidWorks sketches, planes, extrusions, revolves, sweeps, fillets, and measured dimensions. This usually produces a smaller and more maintainable part than converting every polygon into CAD faces.
8. Check scale, orientation, wall thickness, openings, gaps, and critical dimensions. Save the result with File → Save As as part.sldprt.

Use reverse-engineering or intermediate CAD software

High-resolution scans can exceed practical mesh or mesh-BREP limits and make automatic reconstruction slow or unstable. Decimate the mesh in MeshLab or Blender, divide it into logical regions, or use reverse-engineering software such as Geomagic Design X for sectioning, surface fitting, and feature reconstruction. For simple prismatic parts, manual remodeling in SolidWorks is often more accurate than automatic fitting.

Direct online creation of a native SLDPRT is uncommon because the format is proprietary and a mesh contains no feature tree to reconstruct. A reputable service such as CAD Exchanger Cloud can be used, when the current service supports OBJ import and STEP export, to create an intermediate .step file. Open that file in SOLIDWORKS and save it through File → Save As as .sldprt. STEP generally imports as a solid or surface with no original feature history, and the result may still need repair.

Do not upload confidential, regulated, or proprietary designs to an online converter. Use local SOLIDWORKS, CAD Exchanger Desktop, or licensed reverse-engineering software for restricted data, and verify the converter's current format and export limits before relying on it.

Quality and compatibility limits

• Faceted geometry: an OBJ stores polygon approximations, not analytic planes, cylinders, cones, tolerances, or design dimensions. A direct conversion may produce thousands of small faces instead of usable CAD features.
• Scale: confirm a measured dimension after import and apply the correct unit or scale before remodeling.
• Closed geometry: forming a solid requires surfaces or mesh regions without unresolved gaps, self-intersections, or non-manifold edges. A visually closed mesh may still fail validation.
• Appearance: OBJ materials, .mtl references, and texture images may not transfer to SOLIDWORKS appearances. Reapply materials and textures if the visual result matters.
• Accuracy: scanner noise, smoothing, decimation, and polygonization can change hole sizes, edges, and wall thickness. Validate critical dimensions against measured source data before manufacturing.
• Feature history: no automatic converter can reliably infer the original sketches, constraints, feature order, or design intent from an arbitrary polygon mesh. A genuinely parametric SLDPRT requires reverse engineering or manual reconstruction.