In reply to James Gordon:
Oddly I've just done this. I used a standard metal file and it didn't take too long, but this is on Quark picks, DMM and Grivel crampons, not BD.
I'm unsure of what crampons are made of these days but many years ago I cut all the points short on a pair of Salewa Hard Ice Classics for mixed climbing using a hacksaw and went through roughly one blade per point. It was insanely tough stuff and took a long time, I was knackered by the end of it. Filing them into shape was a bit easier but not much. Modern crampons are much softer.