How can I remove aluminium cranks from a steel bottom bracket shaft when it is feels well and truely welded together? I have tried bashing it with No1 bike tuning tool (big lump hammer), using a gear puller (bent chain rings into a taco), gear puller and No1 bike tuning tool (loads of noise, no movement). Both bits are scrap anyway but I want the frame member for mocking up, preferably with a bottom bracket still in it. The frame is aluminium too. Thank you.