Nice site, very informative. I run a small hardwood floor company out of North Carolina in the U.S. I am recently on my own but have been in the business for 15 years. I have purchased a ****** belt sander which runs great but severely digs out the soft grain in the wood, especially red oak, resulting in a rippling effect across the whole floor. Cutting on an angle has no effect and the waves get worse with each successive pass. I have had the machine serviced several times and they can find nothing wrong, also replaced belts, bearings, roller arm, etc.The Waves are not really visible on bare wood but come out when finish or stain is applied and under low angled lighting. I have been able to lesson the problem significantly by using a buffer with a hard plate , followed by screening. This process produces good results but the hard plating ads significant time to the job. any suggestions on this problem would be greatly appreciated as I am some what fanatical about doing a high quality job and although no one else seems to notice these imperfections, I do and it`s driving me up a wall…