Butch, it's not really cupped on the ends, just on the top and bottom on both sides. This pic probably makes it look worse than it is because of how I'd been working on it. The other side was very shallow, the edges were slightly lifted but very minor. I didn't mean to imply that it's just as bad.
The belt is fairly snug across the platen, which is a tempered glass from Tracy. It's certainly possible I've managed to slightly wear the center more than the edges, but I get this issue no matter how I sand, just in varying degrees. I'll take a straight edge to the platen tomorrow and check it. I'd be more worried about the platen except if I turn the steel straight across the platen and grind I still can see the effect. *shrug* it's not the end of the world, I just hope to find something flatter next time. This stuff, if you put a combination square on it you can clearly see daylight.
The belt is fairly snug across the platen, which is a tempered glass from Tracy. It's certainly possible I've managed to slightly wear the center more than the edges, but I get this issue no matter how I sand, just in varying degrees. I'll take a straight edge to the platen tomorrow and check it. I'd be more worried about the platen except if I turn the steel straight across the platen and grind I still can see the effect. *shrug* it's not the end of the world, I just hope to find something flatter next time. This stuff, if you put a combination square on it you can clearly see daylight.