Originally Posted by 3alarmer

...I was hesitant to comment on this, because I'm uncertain that my suggestion will work. Ordinarily I would agree, but in this case the thing being removed is not a simple assembly like a bolt. It's not even a BB unit that is easily disassembled, although I've never gone at one of these with a hydraulic press. They must be assembled somehow in the manufacturing process, and my guess is that the axle and bearing assembly is pressed in from one side.

It's a relatively complicated thing to drill out. and the worst case scenario as a consequence of damaging the threads in the shell are either that it will need to be reamed out and rethreaded in the larger Italian size, or that the future user will need to resort to one of those threadless BB units, which actually work pretty well, even if they are an admission of some measure of failure.

But very much yes on the general avoidance of impact wrenching when working on bicycles. The only other situation I think it might be warranted (as a last ditch attempt to salvage an operation) is on seized freewheel bodies on aluminum hubs. I have one of those I've been back benching for a month now, hoping that heating, ATF/acetone, and time might get it off by normal destructive methods. But I think I'm at the point now where I'll dig out the air impact wrench, turn on the compressor, and sink or swim on that one. Very frustrating, because something like that usually comes off for me without that, and there's an excellent chance it will damage the hub.