In order to use STEP or IGES files from external CAD programs (SolidEdge, Inventor, etc.) in GMSH, the following steps are required:

• Assumed the step file is named model.stp, as a first step, an empty *.GEO file (e. g. model.geo) has to be created in the same directory. Within the GEO file, one single command for opening the step file has to be typed:

  Merge "model.stp";

• The file model.geo can now be opened in GMSH. In order to have a proper mesh size for all points of the geometry, go into the “Mesh” menu and select Mesh–>Define–>Element size at points. Type a proper value (e. g. 20 mm) into the number field and press return. Afterwards, you should select every point of the model with the mouse¹⁾ and finally press “e”.
• In your model.geo file, GMSH has added a line like

  Characteristic Length{<point numbers>} = 20;

• Invoke the meshing algorithm in GMSH by pressing the “2” key and have a close look to the meshed geometry. If there are features, which are not well resolved by the mesh (e. g. small nozzles) it may be required to define a smaller element size at certain points.