Following the instructions I drilled a hole and tapped the thread with no problem. Despite spending over an hour trying 4 different inserts, I was unable to screw any of the inserts into the threaded hole. I bought a screw the size of a threaded hole (14m x 1.5) and it went right in. Then I bought a nut the size of a 14m x 1.5 hole. Despite my constant efforts, I was unable to thread the insert into the nut, which confirmed that the inserts were the wrong size. This product absolutely did not work as advertised. I later bought another kit, a Time Sert kit (much more expensive - $125.00) and spiral coils screwed directly into it.