STEP to STL
Turn a STEP file (.step, .stp) into an STL mesh for 3D printing, rendering or a mesh viewer, free and with no account. Choose Standard or Fine resolution. The mesh is made in your browser, so the file never leaves your computer, and it is checked against the STEP's solid before you can download it.
Your file never leaves your computer: the conversion runs in your browser.
A STEP file describes a part exactly: a hole is a cylinder and a fillet is a fillet. An STL describes the same part with flat triangles, and the only question is how small they are. The converter meshes every face so that no triangle strays further than the chosen tolerance from the true surface, then writes them all to one binary STL in millimetres.
A STEP file holding an assembly or several bodies is flattened: every solid ends up in the one STL, where it sat in the assembly. STL has no way to say which triangles belong to which part, so if you need the parts separately, save each one as its own STEP file first.
The STL is read back and measured. Its volume must match the solid's to within the surface area times the tolerance, and its bounding box to within the tolerance itself. Those two measurements are all the check makes: it does not test that the mesh is closed.
Credits and licences for the projects the converter is built on are on the converter page.
A closed STEP solid normally gives a closed mesh: Open CASCADE, the CAD kernel the converter uses, meshes neighbouring faces along the same points on their shared edge. The check compares the mesh's volume and size with the solid's. It does not prove the mesh is closed, and a small missing face can pass. If a closed mesh matters, run the STL through your slicer's mesh check.
Millimetres, whatever unit the STEP file was saved in. STL carries no unit of its own, and slicers assume millimetres, so the part comes in at its real size.
Not the same STEP. Converting STL to STEP gives a faceted solid, one flat face per triangle, which is exact to the mesh but not to the curved faces you started with. Keep the original STEP.
Lasertally is Windows software for fabrication shops. It opens STEP, IGES, DXF and NC1 files, measures the pierces, cut length and bends off the geometry, and prices the part on your own rate card.