Convert EPRT to STP

A receiving CAD, CAM, inspection, or supplier system may require an editable STEP file when the only available model is an eDrawings part. Because EPRT is normally a viewing publication rather than native CAD data, the reliable solution is to obtain the original part and export it from the authoring CAD system.

What the EPRT format is

.eprt is an eDrawings part file published by SOLIDWORKS or another CAD application supported by eDrawings. It packages a viewable 3D representation with display settings and, depending on the publication options, measurements, sections, markups, and other review data. It is not the original parametric .sldprt model and does not normally contain feature history, sketches, constraints, or editable design features.

Suppliers, engineering departments, and customers use EPRT files to review parts without distributing native CAD files. The eDrawings Viewer opens many EPRT files; eDrawings Professional adds functions such as measurement and, when permitted by the file publisher, export to certain formats. An EPRT publisher can disable STL export, so the presence of an EPRT file does not guarantee that geometry can be extracted.

What the STP format is

.stp and .step are filename extensions for STEP, the ISO 10303 CAD-exchange format. STEP can store precise boundary-representation solid and surface geometry and is supported by SOLIDWORKS, Autodesk Fusion, Inventor, CATIA, Siemens NX, FreeCAD, CAM applications, and inspection software.

STEP is preferable to STL when the receiving system needs analytic faces, edges, holes, curves, or a solid body. STL contains only a triangular mesh and does not preserve parametric features, sketches, dimensions, materials, or feature history.

How to convert the file

Preferred method: export the native model

Ask the EPRT creator for the source part or assembly. In SOLIDWORKS, the creator can open the model and choose File → Save As, select STEP AP214 or STEP AP242, and save an .stp or .step file. AP242 is suitable when the receiving system supports it; AP214 is often a compatible fallback. For an assembly, request an assembly STEP export rather than a new eDrawings publication.

This method preserves accurate B-rep geometry and avoids converting a display mesh. It is the only dependable way to retain the original model's geometric accuracy; STEP still does not generally preserve the source application's feature tree.

Fallback: EPRT to STL to STEP

1. Install eDrawings Professional and open the EPRT file. The standard Viewer generally does not provide STEP export and may not provide STL export.
2. Choose File → Save As and select STL (*.stl) if that option is available. Set the correct units and use a sufficiently fine deviation or resolution. If STL export is unavailable, the EPRT was probably published without extraction permission, and another conversion route cannot reliably recover the model.
3. Import the STL into SOLIDWORKS, Autodesk Fusion, FreeCAD, or another CAD application. Inspect the scale, repair holes and self-intersections, and convert the mesh to a solid only if it is closed and accurate enough for the intended use.
4. Export the repaired body with File → Save As and select STEP AP214 or STEP AP242. In SOLIDWORKS, import options may include Graphics Body, Surface Body, and Solid Body; choose Solid Body only for a watertight mesh of manageable size.

A graphics-body import is display geometry, not a usable STEP solid. Automatic mesh-to-solid conversion can fail on large, open, self-intersecting, or highly detailed meshes; manual surface reconstruction may be required.

Online conversion

There is no generally reliable online service that accepts every EPRT file and exports native STEP geometry. If eDrawings Professional can first create an STL, a service such as CAD Exchanger Cloud may accept the STL and export STEP, subject to its current format list and file limits. This performs the same mesh conversion as desktop software and does not restore lost CAD features or precision.

Do not upload confidential supplier or product data to an online converter unless the service's retention, processing, and access terms are approved by the data owner. Desktop SOLIDWORKS, FreeCAD, Fusion, or another installed CAD application avoids that disclosure.

Quality and compatibility limits

There is normally no direct, reliable EPRT-to-STEP export. An EPRT-to-STL-to-STEP workflow reconstructs a B-rep from triangles; it does not recover the original CAD model. The result can lose exact cylindrical and planar surfaces, small holes, sharp edges, surface continuity, tolerances, units, and feature history. A visually accurate mesh may still be unsuitable for machining, inspection, mating, or dimension-critical redesign.

After export, open the STEP file in the target system, confirm units, measure known dimensions, and inspect cylindrical, planar, and mating faces. Use a finer STL tolerance when geometry requires it, but expect larger files, slower imports, and more repair work. For manufacturing or inspection, obtain the native model or have the reconstructed geometry checked against the supplier's controlled dimensions.