For what it's worth, I've tried all the methods listed above (torch, air chisel, drilling, grinding, cold chisel with engineer's hammer). For me, the easiest, fastest and least damaging method is Grigg's method of a big cold chisel and a big hammer (mine looks like a short handled sledge hammer). My personal record is five whacks on a cross member rivet -- the rivet came out on it's own
)
Just be careful on that last swing ...
John
