How do you do it? I need to get better about doing it. It seems like the bench grinder works the worst for me--overheating, uneven, etc. Using a flap disc on an angle grinder seems to work OK. It seems like a belt grinder would work best if I could find a decent 1" wide machine but most are way underpowered.

How do the pros do it?

Edit: I'm talking about the very heavy 21" blades my ZTR uses. Very much like the ones my 60" belly mower used to use.