Get More Done with One Tool With our Star Mandrel, you can use your die grinder with our uniquely shaped Scotch-Brite™ Stars to clean, polish and lightly deburr the inside diameters of pipe and tubing. Our Star Mandrel is 3 inches in length with a shank size of .0.25 inches. Thread size is 1/4-20 EXT. It will run safely at a maximum RPM of 24,100. Maximize the Value of Your Power Tools Engineered to work effectively with your Die Grinder, our Star Mandrel allows you to do more, more cost-efficiently with your power tools.