When dressing a grinding wheel it must be determined which type of wheel is to be dressed and which type of wheel dresser will be used. If the wheel has not yet been mounted onto the grinding machine it would be well worth checking it for cracks. This is done by putting a small diameter bar through the internal bore of the wheel and letting it sit stationary. Another piece of soft material such as a small length of brass should be used to gently tap the inside face of the grinding wheel. If a clear tone similar to a bell is heard then the wheel is ok and has no cracks, however if it has a dull sound it must not be used as this suggests a crack or fracture. There are various types of wheel dressers, some are to be used on bench grinders and these have a handle with a hard diamond attachment on the other end. They are fed up towards the wheel as it spins and run horizontally back and forth until the wheel is flat and clean looking. When dressing the wheel of a surface grinder the dresser is placed onto the magnetic chuck or other and clamped securely. It should always be placed on the left hand side of the wheel during rotation to avoid jamming and possible injury. The wheel is turned on and the dresser can be moved backwards and forwards using the cross slide and taking small cuts of the wheel. When the wheel is flat and clean looking, the grinding wheel is dressed.