Originally Posted by
obrentharris
It is possible that the butted steerer tube was installed upside down so that the thicker-walled section is at the top rather than in the fork crown where it's supposed to be.
Brent
The Threads are rolled or cut on the tubes Before the steerer tubes are brazed or welded to the forks/crowns.
the Threading process is done in a lathe to allow higher precision, and speed of process.