I forge, and I actually grind a blade 3x during the process of making a knife. First comes the forging....
Grind #1: This is done with a 7" angle grinder to remove all the forge scale and with some practice you can do a decent job of rough grinding the entire thing. I use the angle grinder because forge scale is super tough stuff and will just eat belts by the bucket fulls.
Grind #2: This is my actual rough grinding where I smooth out the profile, and flats, then set up/in the primary bevels. This is done with a 50 grit belt, then cleaned up to at least 120 grit prior to heat treating. (anything less than 120 and you run the risk of stress risers...which can cause tiny cracks during the hardening step)
Grind #3: This is my finish grind. It starts with a NEW 50 grit belt, and I take the blade to nearly complete. I then go straight to a 400 grit belt, clean up all the 50 grit scratches, give the blade a convex edge, then I normally go to hand finishing after that.
Some types of knives dictate that I go about it differently. For example if the blade is very thin (1/8" or less) I will often heat treat, then grind, in an attempt to prevent warpage.