[media = http: //www.youtube.com/watch? v = VB5LRN1AnOM]
This video shows how to make a self-tapping screw. do it yourself. This is not easy, but the process is very interesting. There is a machine that first grinds an iron rod, then with another, but no less interesting device, a thread is applied to a self-tapping screw. This requires special equipment, a lot of time and patience for such a difficult job.