Metal shears

These are usually electrically operated (Figure 3.44),but in some cases can be driven by compressed air (Figure 3.45). They are designed to be used in the hand with an on/off trigger control built in the handle. The blade holding shoe is designed in a spiral so that it parts the metal as it cuts it. The machine is based on the principle of shearing metal,and this is done by a pair of very narrow blades,one of which is usually fixed while the other moves to and fro from the fixed blade at high speed. The blades have a very pronounced angle orset to permit the blade to pierce the sheet for internal cutting. The tool can be easily turned when cutting owing to the narrow width of the blades,and so can cut curved as well as straight shapes. The shears are capable of cutting sheet metal uptoa maximum of 2mm (14SWG) or 3mm (10SWG) aluminium,which more than covers theautomobile requirements.
The shear is used extensively in the cutting of light materials for the construction of new vehicles,but also plays an important role in the removal of damaged sections in crash repairs,as it leaves a nice neat cut and there is no risk of flame damage as with the more traditional methods of oxy-acetylene cutting.