Safety Note Masonry Bit Usage Always wear safety goggles when using any form of masonry bit. Never use a star drill with a struck face that is chipped or mushroomed (flattened and spread out from being struck). 2.8 Snips Snips are used to cut sheet metal, screens, gaskets, and straps. There are four basic types in common use: straight-pattern, combination, duckbill, and aviation. Snips are made for right- handed use, although they can be used in either hand. Other types of snips include curved blade, bulldog, double-cut, and jeweler’s. These snips are used by professional metalworkers. 2.8.1 Straight Snips Straight-pattern snips, Figure 2-40, are gener- ally used for making straight-line cuts. Curved cuts can be made if the curve is not extreme. Sizes 2.7.4 Masonry Bits Masonry bits, Figure 2-38, are used for drilling brick, stone, concrete, and ceramic materials. Such holes are often needed to allow use of concrete anchors or similar fasteners. The special carbide tip resists dulling. Flutes remove dust from the hole so that the bit cuts at maximum efficiency without clogging. Bits may be resharpened on a bench grinder using a silicon carbide grinding wheel. Sizes range from ⅛″ to 1½″ (3 mm to 38 mm). Star drills are designed for hand-drilling holes in masonry. See Figure 2-39. The bit is held in place with one hand while struck with an engi- neer’s hammer held in the other hand. The bit must be rotated slightly after each blow. The four cutting edges steadily chip into the material with each blow. Malco Products, Inc. Figure 2-37. Hole-saw sets include one or more arbors and a range of saw sizes for holes of different diameters. American Tool Companies, Inc. Figure 2-38. Carbide-tipped masonry drills make fast work of holes in concrete, brick, and similar materials. Note the reduced shank on the drill at top. It allows use of the drill in a chuck with an opening smaller than the drill size. Struck face 4 cutting edges Goodheart-Willcox Publisher Figure 2-39. The star drill is struck with a sledge-type hammer to make holes in concrete or masonry materials. Goodheart-Willcox Publisher Figure 2-40. Straight-pattern snips are used primarily for straight cuts but can make gentle curves, if necessary. 30 Heating and Cooling Essentials Copyright Goodheart-Willcox Co., Inc.