Angle grinders are powerful electric or pneumatic grinders with detachable grinding wheels that can be used for a variety of jobs around the house, from cutting small tile and cleaning garden tools to sharpening mower blades and grinding dry mortar. Knowing what you will be using an angle grinder for is important in learning how to use an angle grinder and choosing the right type of grinder and wheel attachments. An angle grinder is a handy and versatile tool that can save you a lot of time and energy, and can be used safely and efficiently by following a few simple instructions.
Choose the grinder that is best suited to your project. Electric grinders are more powerful and are best for large jobs that cover a lot of surface area. Pneumatic grinders are less powerful, but easier to maneuver and are best for smaller jobs in tighter fitting spaces.
Choose the proper discs. Sanding discs and polishing pads are used for finishing work, while cutting discs are used for cutting tile, masonry, steel or pipe and wire brush wheels to remove rust or paint. Grinding discs are also available for grinding metal and stone. Never use a cutting disk for grinding.
Carefully read all the instructions and guidelines, being sure you understand any recommendations from the manufacturer, before using your grinder.
Hold the grinder with a firm grip and against the bulk or body of your work rather than on the edge of it.
Move the grinder across the bulk or body of your work in the direction of the handle to avoid the grinder kicking back and the disc slipping, which may ruin your work and cause injury.
References : http://www.wikihow.com/Use-an-Angle-Grinder