Tutorial: Creating a hexagonal nut in the simplest possible way in Catia.
2 Answers

Hexagonal nut tutorial
Answered with a tutorial: https://grabcad.com/tutorials/tutorial-creating-a-hexagonal-nut-in-the-simplest-possible-way-in-catia

Sorry guys I forgot one thing. U may use hole function which will have the threads as well and that will save your more time . I thank Schrotter for pointing this out. :)