Machinists Tools Catalog
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2 DRILLS · Technical Information DRILLING · Drills are used to make holes in a variety of operations from maintenance & repair to high volume precision hole-making. · Many factors influence the selection process when choosing a drill, including drill style, performance level, tool and workpiece material and drill point angle. · Coatings or surface treatments provide improved tool performance and increase in tool life. DRILL STYLES · Straight Shank: shank diameter matches the cutting diameter. These are the most common drills and are effective on both ferrous and non-ferrous materials. Jobbers length and screw machine length are widely used. SPECIALTY STRAIGHT SHANK DRILLS · Parabolic: used for deep hole drilling and reduce the need for pecking. · Slow Spiral: used for long chipping materials like aluminum and copper. · Fast Spiral: used on softer materials where chip evacuation is important. · Half Round: used in deep hole drilling on soft materials like brass and rubber. · Straight Flute: used on hard materials. · Core: used to enlarge existing holes and are also available in taper shank. SHANK OPTIONS Non-cutting end that is held by a machine tool accessory to drive or hold the drill bit. · Straight Shank: most usual style for modern drill bits. Shank size is always made the same diameter as the drill bit. · Reduced Straight Shank: drill shank diameter is smaller than the drill bit size (cutting diameter). They can drill holes that are larger than the capacity of the drill chuck. Larger cutting diameters than straight shank's drill diameters, so that drill chucks can be used to drill large holes. · Taper (Morse Taper): allows the bit to be mounted directly into the spindle of a drill, lathe tailstock, or (with the use of adapters) into the spindle of milling machines. Has very accurate centering. · SDS: has the advantage of a simple spring-loaded chuck, so that bits can be chucked with a simple and quick hand action. Further, the shank and chuck are uniquely suited to hammer drilling in stone and concrete. LENGTHS In general, the shorter the drill, the better the performance. The shortest length provides the best rigidity thus creating truer holes. · Stub Length: short length drill bits or screw machine drill bits are shorter in flute and overall length than jobbers length drills. Reduces deflection and breakage and gives maximum rigidity and accuracy. For hand and machine drilling. · Jobbers Length: jobbers length drills are the most common type of drill. The length of the flutes is either four or five times the diameter of the drill. For general purpose or heavy duty drilling. · Taper Length: longer flute and overall length than jobbers drill. For drilling deep holes. · Long Length: for drilling deep and hard to reach spots. · Extra Long/Aircraft Length: for drilling extra deep and hard to reach spots.
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