you can't file the top to make it square to the steerer
Damn, I've been doing it wrong all these years. OK, not strictly speaking a file, but I always smooth them off with a stone in the DremelĀ® even if the saw cut is perfectly flat.
Currently only have that pipe cutter or the shittest junior hacksaw imaginable- will prob either need to get the right tools (good blade and something to guide it) or maybe just lbs
Thanks @Scilly.Suffolk @freezing77 et al