Thxs Ed- I know that is the ultimate solution. In watching how fast those who have a 7 or 8 inch platen can do this job is a dream come true! In the interim, I was thinking of getting a 3x21 belt sander ( or something similiar) with several grits of paper- just to be able to hold the blanks vertical and grind the smooth lines from hilt to tip. I think that this should work well enough to be able to save me the hours of hand sanding.
If I'm understanding what you're trying to do correctly, I don't think that will fix your problems.
Almost no one I know grinds their bevels from guard/plunge lines to blade tip, parallel to the spine. Almost everyone grinds perpendicular to the spine, then sands the grind marks out parallel to the spine by hand.
Only on a few styles of thin knives with no plunge lines would what you're describing be feasible. Even then I'm not sure it would be all that practical.
A smoother machine with better quality and wider belts, flatter platen and grinding practice are good places to start working towards better hand sanding.
I wouldn't waste anymore money on something that wasn't a 2" x 72" or 2" x 42" at the very least.
Just my opinions.