Hi Franz, STEP is definitely the way to go for a CNC-machined part, especially with intricate details like internal ribs and threaded holes. It keeps the solid body data intact and handles features like threads, fillets, and complex surfaces way better than IGES. Plus, it plays nicer with modern CAM software like Fusion 360 and Mastercam.

Also, might be worth checking with your manufacturer on whether they prefer modeled threads or just hole callouts. A lot of CNC shops lean towards hole annotations instead of modeled threads since it keeps things simpler in CAM. Hope that helps!

Hey Franz, just a heads-up—IGES files tend to turn solid bodies into surfaces, which can be a pain when importing into CAM software. You might end up with gaps or missing faces, especially in tricky spots like ribs and threaded holes. Unless your manufacturer specifically asks for IGES, definitely stick with STEP. It’ll save you some headaches