Page 55 of Advanced Drilling Equipment by Cooper Power Tools

introduction right angle positive feed tools our positive feed drill motors are available in both in-line and right angle configurations please also see the in-line tool section the right angle tools are rapidly growing in popularity due to their compact size light weight and ease of operation in-line drills have a limited stroke but with a right angle drill a deeper stroke can be achieved by simply applying a longer spindle and nosepiece in addition the fixtures do not have to be as robust with a right angle drill which represents a significant cost savings the tools themselves weigh less and in use are closer to the fixture resulting in less deflection of the fixture right angle tools have also been shown to reduce operator fatigue in general positive feed drills are used for the larger holes and heavier structures in the aircraft industry such as the spars and the ribs primarily in landing gear wing and fuselage joins positive feed drills produce a hole in a predictable and constant time with each revolution of the spindle the cutter travels a precise distance i.e onethousandth of an inch or three-thousandths of an inch depending on the settings this is true whether the tool is drilling air or drilling a tough alloy the benefit is that burrs caused by surging of the cutter on the exit side of the cycle are virtually eliminated spindle since the cutter advances a precise guard distance with each revolution the cutter differential feed gear and does not rotate without cutting this differential drive gear reduces heat and deformation resulting feed stop air motor in less chance of the material work collar feed hardening engagement many of the accessories for our spindle lever in-line and right angle tools are interchangeable such as chucks nose pieces motors and gears how positive feed right angle drills operate the fixed rate of spindle advancement feed for each rotation of the drill spindle in right angle tools is accomplished by differential gearing the spindle of a right angle drill has external left-hand threads and four drive grooves that run the length of the spindle the spindle fits into and through two gears the spindle drive gear and the spindle feed gear the spindle drive gear has internal male splines that engage the drive grooves on the spindle when the air motor is turned on the spindle drive gear rotates turning the spindle the spindle feed gear is threaded internally to match the external thread of the spindle and its function is to spindle feed gear threaded spindle drive gear splined tool nose 2-2

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