IGES file: what it is and what to use instead

What IGES is

IGES was created in the USA in 1980 so that companies could send drawings between different CAD systems. It stores curves and surfaces, but many versions do not store solid bodies properly. That is why STEP exists today, which handles this better and has replaced IGES almost everywhere in the CAD world.

You mostly find IGES in older engineering data, from suppliers or in company archives.

Why not to send IGES for printing

Printing needs a closed solid. IGES often contains only surfaces that may not meet exactly, and holes can be left in the model once it is opened. The print then fails, or the model has to be repaired first. Our calculator does not accept IGES, but it does accept STEP, STL, 3MF and OBJ up to 50 MB.

The difference from mesh formats: STL is made of triangles, while IGES and STEP hold exact mathematical surfaces. For printing, the model is converted to layers in the end anyway.

How to prepare IGES for an order

1. Open the file in a CAD program such as FreeCAD or Fusion.
2. Check that the surfaces form a closed object, and stitch them into a solid if needed.
3. Export as STEP if you want to keep exact dimensions, or as STL if the model is finished.
4. Check the dimensions before uploading. One part has to fit within 246 × 246 × 256 mm.

For technical parts, think about tolerances too: a cavity made exactly to the drawing will come out slightly smaller after printing, so design mating surfaces with a little clearance. You will see the price right after uploading, calculated from the real grams and print time.

Why STEP is worth it

STEP holds whole solids with exact geometry, so you do not need to repair it after importing it into a slicer, and the dimensions stay in millimetres. If you can, ask your supplier for STEP or STL straight away. It saves a round of emails.

If you made the IGES yourself in an old CAD program that can do nothing else, just open it in a newer program and save it as STEP. Watch for a change of units, and check one dimension with the measuring tool in the program.