I made a sanding disk for my old tablesaw for edging boards. the disk was made from 1/2" thick aluminum with the outer 3" tapered at a 5 degree angle (like the bottom of a dinner plate) When the disk is leaned in at a 5 degree angle you get a perpindicular face and only the centerline of the disk makes contact with the stock leaving roughly straght cut marks. As for speed, if you are only using it for sanding get a smaller motor pulley or a larger driven pulley.