The dreaded chatter... it's a right bastard, that. A decent operator shouldn't let it get out of hand, though.
Originally Posted by
bradtx
It's more important to face the BB shell on an unbuilt bike.
Why? Given the bike was specced with square taper, perhaps the BB wasn't faced, or faced to the same standard as it should be for an external BB.
Use a flat file to remove any paint, being sure to keep it across the circumfrence at all times. This can also show whether you need to face the BB or not.
It can't tell you how square the cuts are.