ORIGINAL: Grits
And if you don't have a cutoff wheel or a grinder, follow proptops advice about running a nut on the shaft and if there is room, lock the piece to be cut off down in a vice and get a hack saw after it. You can run the nut out 1 thread longer than you need and use the nut as a cutting guide. Afterwards dress the end with a file and last, run the nut off using a back and forth type motion to finish the threads. A drop of oil might help the last part and whatever you do, cover the engine and bearing so no metal shavings or metallic dust can get in. Good luck.
a hack saw, and about a day and a half. this cranks are hard, I trying cutting one. their made out of harden steel, I don't think a hack saw would do it. you would probably go through alot of blade.
but a dremel and a cut-off wheel would do nice.