Bicycle Mechanics - removing tapered cranks

Here's my question: how hard should i have to crank on the wrench to get my cranks off? using the shimano tapered tool, i cranked real hard, and got nowhere.

If the crack is seized on, then quite hard. Apply some WD-40 to penetrate the threads.
Make sure you are turning in the right direction.
Use a metal tube as an extension to get more leverage.

If you apply a light smear of grease to the tapers, they come off easilty, but to grease or no-to-grease is a religious matter.

Have you tried heating the end of the crank that's stuck to the BB spindle? Not red hot obviously because this would affect the metal but 'til it's just too hot to touch. This will cause the aluminium crank to expand slightly and hopefully allow it to be removed :).

Forgive me if this sounds stupid, but I did this. You need to make sure you take out the washer under the crank bolt, if there is a separate washer. The first time I tried to remove a crank the washer stayed without my realizing it. ALSO, there are two different crank extractors, one for the square taper and one for Shimano hollow pipe billet spindle bb's. The former has a plug about 7-8 mm (3/8"), the latter closer to 15 mm (5/8"). If you were sold the latter type it will not work on square taper. I have had a couple that took a extra effort, but none that required what I considered excessive force. When dealing with the fine extractor threads on an aluminum crank you are right to excercise considerable caution.