I have a 12 mm. ( 1/2 ) " belt sander that is perfect for sanding the ramps in a variator, made by black and decker, I can change the ramps in a hour, I file the ramp so it is a lot longer ,so the sliders move better for me so my rpm. is lower at speed,. I checked the belt on the variator with the cover off and the belt rides higher on the variator, with my mods, = lower rpm. at speed