I am forging blades. Learning to get them pretty close to shape. Initially grinding with 40-60 grit (concave grind). I have a very good (Bader) belt grinder and am using good quality (regalite) belts. I go from 60 to 120. You know--the sixties are just for hogging out and shaping. I really bear down. When I get to the 120 I am trying to polish somewhat and I can't bear down at all. The belt seams bang on the platten and dig every revolution. So I am hand sanding for 4 or five hours. I like hand work but how can I get more out of my grinder?

Try using belts that are put together with a finger joint instead of a lapped joint.

120 grit is still plenty coarse enough to be used for refining the grind rather than polishing. I would suggest lighter pressure on the wheel, and the addition of a couple more grits (say, 220 and 400). I wouldn't start worrying about the finish until you get to 400 grit.

If you have Steve Johnson's abilities, you can go right from your rough grinding to 400.