CAD translation

What gets translated#

A CAD translator reads one system's geometry, topology, assembly structure, and metadata, then writes the closest representation supported by the target format. Neutral formats such as STEP and IGES exist because every CAD system otherwise has to understand every other application's private data model.

STEP Tools describes STEP as an ISO effort to replace separate national exchange formats and reduce repeated data entry and errors between technical systems.

Geometry is only part of the model#

A translated solid may keep accurate faces and edges while losing the feature tree, sketch constraints, configurations, and application-specific relationships. Onshape's export documentation states that downloaded data does not contain features or parametric history.

Format names alone do not establish what survives. Onshape's supported-format table, for example, lists STEP imports as geometry and face color, while imported STL and OBJ files are view-and-reference meshes that cannot be edited as ordinary solid geometry.

Common translation failures#

Different kernels use different geometric tolerances and validity rules. A translation can produce gaps between surfaces, sliver faces, split cylinders, inverted orientation, missing names, shifted assemblies, or lost manufacturing annotations. The file may open without being ready for downstream work.

Validate the result in the receiving system. Check units, bounding dimensions, body count, assembly placement, solid status, analytic faces, and any metadata that the next operation needs.