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How do I enable the grid in MED?


In MED press File->Preferences->Video Out, and then mark 2dgrid and 3dgrid
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How to I convert the 3D model to 3D triangle mesh in Blender before exporting the 3D model?


Select your model and enter the Edit mode, then select all the faces or vertices, then press Space on your keyboard, in opened menu choose Edit->Faces->Convert to triangles.

Blender can also convert triangles back to quads, in the same menu just choose Convert to quads.