Document 5RY8722Vza7OD65mQd5pwj9z

WOODWORKING MACHINERY stbaichteninc Restoring the blade to a straight plane surface tensioninc Giving every part of the saw the proper tension for the type of work it has to do filinc and cnnmorc Sharpening the edges of the teeth and restoring them to the correct pitch (angle with relation to the center of the saw) and shape cumminc Deepening and rounding the gullets between the teeth As the teeth wear shorter, the gullets need to be deepened swacinc and settznc Thickening or bending the teeth so that the saw kerf will be thicker than the blade Proper operation A saw m good condi tion and running at correct speed should cut easily The operator should not crowd the saw, that is, force the stock faster than it can be easily cut If the saw does not cut as fast as it should, or if it does not saw a clean, straight line, it is probable that something is wrong with the saw or the running speed These conditions, potential sources of accidents, should be checked and remedied Circular saws are normally designed to operate at run speed of 10,000 fpm Some saws, however, are tensioned to run at higher speeds, which are marked on the saw by the manufacturer Following is the formula for determining the peripheral or tun speed of a saw when revolutions per minute are known S = 0 26 Dr where S = nm speed in fpm D = diam of blade, in r = revolutions per mm The saw should properly fit the mandrel The arbor or mandrel on which the saw is hung must be true and must fit the bearing boxes without chattering, end play, or heat ing The stem of the mandrel must be true if the saw is to slip easily up to and against the fixed collar Only the outer edge of the collar should come id contact with the saw when it is tightly clamped in position If the inside of the collar has not been machined out prop erly, it will force the nm of the saw out of lino When the saw blade comes in contact with the stock being cut, a buckling effect on the saw is produced After the loose Fig 25-6 A cutoff sow guarded with a hinged (ftootmg) hood guard Courtesy Western Electric Company collar is fastened securely m place, it is well to test the saw with a straightedge This test is of considerable importance on head ng circular saws as well as on edgers and trimmers A pm or stop should be provided to pre vent men from placing on the mandrel a saw larger than allowable for the speed of the mandrel Overhead swing saws and straight U&e pull cutoff saws Overhead swing saws and cutoff saws cause hand injuries because of several charactensiles of the saw Hands are cut with the saw in idling position when the opera tor reaches to remove a sawed section of board or a piece of scrap or when he meas ures a board or places it m position for the cut The operator's hands may likewise be struck by the saw as it bounces forward from the idle position, or swings or drifts forward when the spring or counterweight fails The operator may pull the saw against his hands or may suffer body cuts from a saw that swings beyond its safe limits Guards Cutoff saws should be guarded 25-7