STEP to STL

From CAD to 3D printing

STEP is the format used to exchange parts between mechanical design programs: it stores the exact surfaces, with perfect curves. Slicers, on the other hand, work with triangles. Here you convert one into the other without installing anything.

Curves are turned into triangles fine enough not to show when printed (about 6° per segment). The size is kept: STEP does state its unit, and it's converted to millimeters.

How it works inside

To read STEP it uses Open CASCADE, the same geometry engine as FreeCAD, compiled to run in the browser. It's a file of about 3 MB that downloads only the first time you convert a STEP; the rest of Plastilo's pages don't load it. Your file is read in your browser and isn't sent anywhere.

If something looks off

• Slow to read: large parts or ones with lots of curves can take a few seconds. Wait for the preview to appear.
• It won't read: export the STEP again as AP214 or AP242 from your program.
• Several parts: an assembly comes out with all its parts in the same STL, in place.

Tips

• If your CAD program exports STL directly, that works too; STEP is handy when the part was sent to you or you downloaded it that way.
• Check the size in the preview: if it's a thousand times bigger or smaller, the file was saved with another unit.
• For assemblies, export each part separately if you'll print them separately.
• If the warning says the mesh has holes, the repair button in PrusaSlicer or Bambu Studio usually fixes it.

Frequently asked questions