In a typical Straight/die grinder, the power from the engine is transmitted to a gear head which has an abrasive disc that spins at a rapid rate. These discs can be of different types that are suitable for varied jobs involving different target materials. Some of these disc types include abrasive grinding discs, sanding discs, cut-off discs, wire-brush wheels, and buffing pads. Due to the extreme speed at which the wheel or the disc rotates, the force is projected laterally during cutting. To counter this torque, the grinder incorporates large bearings.

The usage of the correct wheel/disc for different materials plays a very important part in the smooth functioning of the tool. Normally, for metal cutting, the grinder uses a depressed center wheel; for wood cutting, a flap wheel is used; and for stone cutting, a GC wheel is used. A hinged face plate with wing nut fasteners helps in easier wheel removal.

Sometimes, due to the extra pressure that needs to be applied on the surface to be cut, the grinder has a side handle, enabling the user to grip the device with both hands. To make the tool more efficient and to lessen the energy expenditure of the user, the power-to-weight ratio of the tool is increased.

Die grinders have a small collet measuring ¼”, a special collet nut, and a small disc/wheel that is attached to the tool. The small disc/wheel size compliments the high rotating speed of 14,500 rpm upwards.

The most common speed of the rotating wheel in straight grinder available today is 5,500 rpm and can go up to 7000 rpm. This high speed coupled with the operation of the engine can generate a large amount of heat in the tool and the vented metal gear case helps to dissipate the same.