X-Post from Classic and Vintage: If I pick up a bike with a threaded steerer, is it possible to replace the steerer tube without having to replace the entire steel fork? I don't like quil stems and most old steel Bianchis have threaded steerers. I know I can get an adapter but I am unsure about those things.
Takes a lot of heat to melt the brazing material in the fork crown to pull the fork steerer out,
but a skilled bike frame builder can , perhaps cut down the threaded steerer tube ,
sleeve the inside, then
tig weld a new piece of steel tubing on, and get it still, dead on, aligned.
I won't try to convince you to like threaded, but they do have advantages. As far as adapters go, I have used them, and had no issues. You just have to be sure you tighten them properly, and the stem also. Kind of like you would with threadless.