• Hacksaws- A hacksaw (Fig. 7.16) consists of an adjustable framewith a handle and a replaceable hacksaw blade. Bladesare commonly available in 10- and 12-inch lengths. Thecoarseness of the cutting teeth is stated in number ofteeth per inch, usually 14, 18, 24, or 32 teeth per inch。The finer blades are used for materials of thin cra.svetion. Select a blade that will have at least 2 teeth cutting at all times. Use the entire length of the blade oneach stroke.- Apply light pressure on the firw ardl stroke and releasethe pressure on the return stroke. When replacing ahack-saw blade, install it with the teeth pointing :nwayfrom the handle.Fig. 7.16 Adjustable frame hacksawFig. 7.17 Power-driven hole saw