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\viewkind4\uc1\pard\qc\cf1\lang2057\b\f0\fs24 G74 (End Face Peck Drilling Cycle)\cf0
\par \pard
\par \cf2\b0\fs20 The G74 code instructs the machine to perform a peck drilling cycle. The centreline of the drill runs parallel to the Z axis, ie, the drill will make holes in the face end of the billet.\cf0\b\fs24
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\par \b A G74 command is written in the following format :
\par G74 R (1) ;
\par G74 X (U) Z (W) P Q R (2) F ;
\par
\par where,
\par R(1) is the peck return amount.
\par X (U) is the diameter of the bore if stepover is used (ie, stepping along the X axis to repeat the peck cycle).
\par Z (W) is the depth of the bore.
\par P is the stepover in the X axis measured in micron's (without sign).
\par Q is the pecking depth in the Z axis measured in micron's (without sign).
\par F is the feedrate.\fs24
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\par \cf2\b0\fs20
\par Peck drilling refers to the method used for removing the material, ie, the the drill will move a set amount into the material, then withdraw to allow swarf and scrap drop out, before cutting further into the material.
\par The G74 code allows two different methods of drilling:
\par 1) A tipped U-drill can drill into a billet, then move along the X axis and repeat the operation several times if required, ie, it can be used to drill holes off-centre.
\par
\par 2) A standard drill can also be used. If the words X , P and R are omitted from the G74 command, a hole will be generated by pecking in stages (each stage measuring a depth of Q ) to a total depth of Z .
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