Die grinders are small, handheld power tool that has a rotating spindle where a collet holds the cutting bit. The grinding bit that rotates at very high speed is used for removing material from the work-piece. They look similar to rotary tools and are usually powered by compressed air or electricity. When combined with the right attachment, die grinders are capable of doing a wide variety of different tasks. Die grinders are primarily meant to work with metal (specifically for Tool and Die making). But one can also use them on other, more sensitive materials like plastic and wood to polish, sand, cut, grind, or hone various materials. They are mainly used to rework dies, polish metals, smooth out surfaces, rust removal and sharpening blades.