3D printing · Meshes · CAD drawings
STL stores triangles; STEP stores mathematical surfaces. Converting between them means building real B-Rep topology — shared edges, closed shells — so CAD software can knit the result into a solid body rather than treating it as a picture.
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STEP export merges coplanar triangles into real planar faces, so flat surfaces come through as single selectable, dimensionable planes and CAD imports them quickly. Curved surfaces stay faceted, and there are no parametric features — a mesh has no record of them. Simplify is optional here; leave it off for the most accurate dimensions.
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Exported one face per triangle, a flat surface becomes thousands of tiny faces: painfully slow to import and impossible to select or dimension. Coplanar triangles are merged into single planar faces first, which on a typical part cuts the face count by twenty to forty times and gives you surfaces you can actually click on and measure against.
This is not reverse engineering. A mesh has no record that a surface was once a cylinder, so curved areas stay as many small flat facets. You get a solid body you can measure, cut, and use in an assembly — not an editable parametric model with a feature tree.
Import it as reference geometry, then sketch on top of it: take hole positions and spacings from the faceted body and model the real part fresh with proper features. That is faster than fighting a faceted import, and it is what people do with scan data for exactly the same reason.
See all supported formats — meshes, 2D drawings and g-code, all converted in your browser.
Yes. Coplanar triangles are merged into single planar faces and assembled into a closed solid, so CAD software imports it as a solid body rather than a mesh.
It opens as a solid body you can measure, cut and use in an assembly, but not as a parametric model with a feature tree. A mesh holds no record of the features it was built from, so those cannot be recovered.
Every distinct surface becomes a CAD face. Flat areas merge into single faces, but curved surfaces stay as many small facets because the mesh has no record that they were once cylinders.
No. Reverse engineering means recognising that a set of triangles was once a cylinder or a fillet and rebuilding those surfaces exactly. That is an unsolved problem in the general case, and tools that attempt it cost thousands and still need manual work.
If a file will not convert, or the result looks wrong, I would rather hear about it. Include the format and roughly what you were doing — that is usually enough to reproduce it.