Originally Posted by
miamijim
...We had tool that was designed to 'raise' the metal. You'd roate it around a few times and the wheels would dig and leave a pattern behind. It worked OK.
The process is called knurling. It displaces metal to create small ridges or mounds higher than the orignal surface of the metal. Inexpensive bicycles often have the bottom of the steerer tube knurled to hold the crown race in place without the need of a precision machined collar/flange. If done properly, it is an effective solution, though it will not stand up to repeated removal and installation of crown races like a machined collar/flange.