It says here to sharpen at a 45 degree angle. I'm sure you all know that eHow is the authority on how to do virtually anything and they're always right ;
I'm just having a hard time following how to do step 6, balancing the blade, since step 5 was to re-attach the blade to the mower!
http://www.ehow.com/how_2058792_shar...wer-blade.html