Supported Formats
LOP accepts STEP files conforming to the ISO 10303 standard. This is the most widely supported 3D CAD interchange format and is natively exported by every major CAD platform.
Accepted File Formats
| Format | Extension | Support |
|---|---|---|
| STEP AP203 (ISO 10303-203) | .step, .stp | Fully supported |
| STEP AP214 (ISO 10303-214) | .step, .stp | Fully supported |
| IGES | .igs, .iges | Not supported |
| STL | .stl | Not supported |
| OBJ | .obj | Not supported |
| FBX | .fbx | Not supported |
If your workflow currently produces IGES or STL files, open the file in any CAD viewer and re-export it as STEP AP214. Most free CAD viewers (FreeCAD, eDrawings, Onshape) support this conversion.
STEP AP203 vs AP214
Both AP203 and AP214 are accepted, but AP214 is recommended for better compatibility.
STEP AP203 (Configuration Controlled 3D Design) — the older protocol, focused on geometric shape data only. Widely supported but does not carry color, layer, or material information.
STEP AP214 (Automotive Design) — the modern protocol with a richer data model. Carries color and appearance information that LOP can use to set item colors automatically. If your model has color-coded parts, AP214 preserves this in the import.
When exporting from your CAD tool, select AP214 if both options are available.
Compatible CAD Software
The following CAD platforms can export STEP files compatible with LOP. Export instructions vary by version; consult your software's documentation for the exact menu path.
SolidWorks
File → Save As → File Type: STEP AP214 (*.step)
Recommended settings:
- Export: Solid and surface geometry
- Include: Default (no internal hidden bodies needed)
- Do not embed thumbnail
Autodesk Fusion 360
File → Export → Format: STEP (*.step)
Fusion 360 exports AP214 by default. No additional configuration is needed.
CATIA V5 / V6
File → Save As → Type: STEP (*.stp)
For assemblies, ensure "Save all instances" is selected to include all sub-parts in a single file.
Siemens NX (Unigraphics)
File → Export → STEP 214
In the export dialog, set Output as: Solid and sheet bodies.
Autodesk Inventor
File → Save As → Save As Type: STEP Files (*.stp)
Select AP214 in the STEP Export Options dialog.
PTC Creo (Pro/ENGINEER)
File → Save a Copy → Type: STEP (*.stp)
Set the export profile to AP214 for best results.
FreeCAD (open source)
File → Export → STEP with Colors (*.step, *.stp)
FreeCAD exports AP214 with color information when using the colored STEP option.
Onshape (cloud-based)
Right-click the Part Studio or Assembly → Export → Format: STEP
Single-Part vs Assembly Files
Both single-part and assembly STEP files are accepted.
Single-part files contain one solid body. These process fastest and most reliably.
Assembly files contain multiple parts with positional relationships. LOP reads the assembly hierarchy and treats the entire assembly as a single item with a unified bounding box. The 3D preview renders all components in their correct relative positions.
Large assemblies with many sub-components (hundreds of parts) may exceed the processing time limit and fail. If you experience timeouts with assembly files, try one of these approaches:
- Export only the outer shell / enclosure as a single body
- Suppress internal components in your CAD tool before export
- Split the assembly into logical sub-assemblies and create separate item records
Geometry Requirements
LOP's parser expects manifold solid geometry — the mathematical requirement that every edge is shared by exactly two faces, with no holes or gaps in the surface. Most CAD-native solid models are manifold by construction, but geometry that has been imported, repaired, or exported multiple times can develop surface errors.
If you encounter parsing failures, your CAD tool's geometry repair function (or a dedicated mesh repair tool like MeshLab or Netfabb) can often fix manifold issues.
File Size Limits
- Maximum file size: 250 MB
- Recommended maximum for reliable processing: 100 MB
Files over 100 MB will process successfully in most cases but take longer and carry a higher risk of timeout. If your file is very large, use your CAD tool to:
- Remove internal components and features not visible from the outside
- Suppress representations of threaded holes and fine surface details
- Use a lower tessellation quality setting on any mesh-based features
- Export only the solid bodies that define the external envelope
Units and Coordinate Systems
STEP files encode dimensional units internally. LOP reads the unit specification from the file header and converts all dimensions to millimeters automatically. You do not need to pre-scale your model.
Supported units in STEP files: millimeters, centimeters, inches, feet. All are converted to mm on import.
The bounding box is computed relative to the world axis system in the file. If your model is oriented at an angle relative to the world axes, the bounding box will be larger than the actual part envelope. Orient the model with its packing face aligned to the XY plane before export for accurate results.