STEP CAD
CAD & 3DSTP commonly names STEP CAD exchange files. Before editing a received part, inspect units, component count, assembly structure and the supported application protocol. Visible geometry does not imply recovered native constraints/history. Check tessellation and physical size when exporting STL for printing.
- What it is used for
- Exchange of CAD parts and geometry
- What the file contains
- Text
All sections, questions and sources
Content reviewed： · Editor：Kai
Opening steps
Choose your environment or purpose to see its steps.
Menu labels and support vary by app, OS and version. Preserve the original before making changes.
Troubleshooting by symptom
- No history: exchanged geometry differs from native modeling history; request the original if needed.
- Missing parts/color: inspect export selection, assembly structure and supported variant.
- Mesh-only result: check whether the importer/workflow tessellated the geometry.
- Wrong dimensions: compare known measurements and units.
- Faceted curves: inspect display and export tessellation separately.
- Hole closes when slicing: compare tessellation accuracy and source holes.
STEP → STL / native CAD document
- Inspect parts/dimensions in CAD and save a native working copy.
- For printing, export the selected parts as meshes and verify tessellation/size.
- Compare dimensions and small holes in the exported mesh.
STL tessellates smooth CAD surfaces; keep the STEP source.
Exchange geometry versus native source
Request native CAD when changes require constraints, parameters or history.
Example: measure a known 100mm edge numerically after import.
Source for these steps：FreeCAD Project · FreeCAD features — File formats / FreeCAD Project · A FreeCAD Manual / Prusa Research · PrusaSlicer — Supported file formats
What tessellation changes
Mesh export approximates curved geometry; inspect small features and units and retain the STEP original.
Source for these steps：FreeCAD Project · FreeCAD features — File formats / FreeCAD Project · A FreeCAD Manual / Prusa Research · PrusaSlicer — Supported file formats
Related-format differences
| Format / method | Role | What to verify |
|---|---|---|
| STP / STEP | CAD exchange geometry | Units/parts |
| Native CAD | Design history | Original application |
| STL | Triangle mesh | Tolerance/units |
Handling and security
Check sharing permission for dimensions/manufacturing data and inspect included assembly components.
Questions and answers
Can STP replace the native CAD document?
It can exchange geometry; work needing history, constraints or external references may require the native document and assets.
Do STP and STEP suffixes serve different purposes?
They normally name STEP exchange data; verify actual specification/application support.
Does slicer import preserve CAD editing?
The workflow may tessellate the geometry.
Are assembly names preserved?
It depends on export/import support; compare names, counts and placement.
What if dimensions differ by a factor of 25.4?
Inspect inch/millimetre interpretation against known dimensions and import settings.
Format facts: name, steward and MIME type
- Formal name
- STEP (ISO 10303 product data exchange)
- Steward / specification
- ISO
- MIME type
- Depends on the producer or server; an extension alone does not establish a MIME type.
Primary and official sources
- Project documentationFreeCAD features — File formats
Lists supported import/export formats, including STEP and STL.
FreeCAD Project · Link checked： - Project documentationA FreeCAD Manual
Explains exchange formats; this older manual may differ from current UI.
FreeCAD Project · Link checked： - Software documentationPrusaSlicer — Supported file formats
Documents 3MF projects and STL/STEP/OBJ import behavior.
Prusa Research · Link checked：