I used to sharpen my blades with a 6" bench grinder, i always had a sharp edge, but it was inconsistent (to say the least). Today, i had some time to kill, so when i swapped in my mulching blades i threw them in the vice and hand filed them. the only thing i can say is: WOW, what a difference. i was able to get a razor sharp edge on all the blades in about 10-15 minutes (had to get some dings and nicks out of the edge). The major difference is the consistency of the edge, very smooth. I will definitely be hand filing my blades from now on, plus it i'll get considerably more life out of the blades by hand filing and leaving more steel on the blade instead of burning through it with the grinder. So, have any of you ever tried it?