STEP is a family of standards for product-model interchange. In this workbench, STEP/STP support focuses on self-contained boundary-representation CAD geometry: faces, edges, shells and solids with supported length units and assembly placements. STEP is not simply another triangle-mesh container.
- Geometry
- The supported subset describes B-rep surfaces and topology, which must be tessellated for a browser mesh preview.
- Units
- Explicit supported source length units are required; the CAD runtime normalizes the imported geometry to mm.
- Assembly
- Supported nested placements are applied. The original assembly tree is not offered as an editable structure.
- Filename
- .step and .stp belong to the same viewer/converter intent and use the same pages.
STEP vs STL: retain the source when editing matters
An STL approximation is convenient for mesh workflows, but curved faces become triangles and CAD topology is lost. Keep STEP for subsequent CAD interchange. Converting a triangulated file back into a faceted wrapper would not restore analytic surfaces or design history; no STL→STEP tool is published here.
Tessellation trades detail for processing cost
Draft, Balanced and Fine select different linear/angular deflection settings. Finer settings generally produce more triangles around curved surfaces and can hit the same processing budget sooner. Displayed bounds come from the tessellated result rather than exact analytic measurements.