Yeah, I'm doing it without tape. I fully realized it would take a lot of work to accomplish this way, but not quite THIS much work. I'm familiar with the rolling x stroke, and have used it on my other vintage pieces (even the straightest among them was a slight smile at the toe) with great success, but I think it's just that the blade angle was all wonky when I got it.

If I were to use 1000 grit sandpaper, how would I go about keeping that flat? I've tried stretching it flat over a stone before, but the paper would "bubble" slightly over the surface of it. Any fixes?