A belt sander is disclosed that may include a sanding assembly having a first roller and a second roller, the sanding assembly being configured to receive a sanding belt around the first roller and the second roller to define a sanding surface therebetweeen. For this purpose, rotating speed of a motor is gradually slowed down with the lapse of time from a high target speed and then settled at a low target speed, if an irregularity detection unit determines there is an irregular condition based on an output of a wound-up diameter detector. The sound chambers are placed between a waveguides and a flattened conical horns of secondary waveguides. A third step involves inserting coil tubing through the travelling ball valve and the standing ball valve to cleanout the entire workstring and pump. A stabilizer tip having a slotted sleeve and an angulated planar portion is removably carried at the forward end portion of the cylinder portion proximate the reduced nose and is adjustably positionable thereon to control direction of planar board movement relative to moving water. Then forming a second power rail over the first power rail.