Get yourself a 4" air sander or a 4.5" electric grinder with a flap style sanding disc. Just put the blade in a vice and make a couple passes across the blade. i find this method so much quicker and easier.
Which Metal Composition and which grit? Thanks for the info, I think I'll get one once I find out some more about them.
I'm gonna guess by the description that the Basic Aluminum Oxide works since we're generally not removing ALOT of material from the blades? And I'm gonna guess a 60, 80 or 120 grit as you want it to be relativly fine? I'm guessing a 36 grit takes off WAY too much too fast?
I use a 80 grit but I'm sure 120 would work good enough. I have found that I don't heat the blade up as much using those discs too. Oh just get the basic alum. oxide and you can get them just about at any hardware store.
I find this way much faster than a bench grinder. Yes, I take the blades off and put them in a vise, on my smaller mowers. You will be amazed at how fast you can sharpen a blade and how sharp you can get them with just a couple of passes.