Text to STEP: GrandpaCAD now makes STEP files

Until now every part you got out of GrandpaCAD was a mesh: STL, 3MF, OBJ or GLB. Great for the printer. A dead end the moment you wanted to open it in Fusion and move a hole.

Now a CAD part can come with a real STEP file. Drag the slider to see the difference: same plate, same 20 mm hole, saved two ways.

What is a STEP file?

STEP (.step or .stp, standardised as ISO 10303) is the format CAD programs use to hand exact geometry to each other. It doesn't store triangles. It stores faces, edges and real curves, so a hole is a cylinder with a diameter and a flat side is a plane.

That's why a STEP opens in Fusion, FreeCAD, SolidWorks or Onshape as a solid you can keep working on: select a face, measure it, fillet an edge, move a hole 2 mm to the left. It's also the file machine shops and manufacturers accept when you want a part milled, turned or quoted.

STEP vs STL

Printing it at home? STL or 3MF is all you need, and that's still what you get by default. Want to keep designing it, or have it made? Get the STEP.

Can't I just convert STL to STEP?

You can, but it won't get you much. STL to STEP converters wrap every triangle in its own flat STEP face. You get a valid .step file with thousands of faces, the hole is still a polygon, and there's no cylinder to select and no diameter to change. The other direction works fine (our STEP to STL converter does it right in the browser), because you're only throwing information away.

A useful STEP has to be built as exact geometry from the start. That's what GrandpaCAD does now.

How to get a STEP file from GrandpaCAD

Say so in your message. "As a STEP file", "I want to open it in FreeCAD" or "this is going to a CNC shop" are all enough, and the agent builds that part with its exact-geometry engine. Attaching a STEP file works too.

Need STEP for everything? Turn on "I need STEP / CAD files" in Settings → Generation and every CAD part is built that way. With it on, a model may take a few more steps to finish.

When the part is done, the download menu in the viewer has a "Download .step" option next to the usual download. Downloads are part of the paid plans, same as every other format. The parameters panel still works too: change the width and the STEP is rebuilt along with the model.

Edit a STEP file you already have

Attach a .step file to your message and say what to change: add a hole, cut a slot, build a bracket around it. Want to look inside it first? Open it in the free STEP viewer.

What doesn't get a STEP

• Sculpted, organic models (figurines, creatures) are meshes, and they stay meshes.
• A part that was already built as a mesh has no STEP. Ask for one in the same chat and the agent rebuilds it.