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Two, Three, and Four Flute Drills Diameter at Point Drill Diameter Range (inclusive) Tolerance #97 to #81 (.0059 to .0130) +.0002 to -.0002 Over #81 to 1/8" (Over .0130 to .1250) +.0000 to -.0005 Over 1/8" to 1/4" (Over .1250 to .2500) +.0000 to -.0007 Over 1/4" to 1/2" (Over .2500 to .5000) +.0000 to -.0010 Over 1/2" to 1" (Over .5000 to 1.0000) +.0000 to -.0012 Over 1" to 2" (Over 1.0000 to 2.0000) +.0000 to -.0015 Over 2" to 3-1/2" (Over 2.0000 to 3.5000) +.0000 to -.0020 Shank Diameter Drill Diameter Range (inclusive) Tolerance #97 to #81 (.0059 to .0130) +.0002 to -.0002 Over #81 to 1/8" (Over .0130 to .1250) +.0000 to -.0025 Over 1/8" to 1/4" (Over .1250 to .2500) +.0005 to -.0030 Over 1/4" to 1/2" (Over .2500 to .5000) +.0005 to -.0045 Over 1/2" to 2" (Over .5000 to 2.0000) +.0005 to -.0030 Back Taper Drill Diameter Range (inclusive) Tolerance (per inch) #97 to #81 (.0059 to .0130) None Over #81 to 1/8" (Over .0130 to .1250) +.0000 to -.0008 Over 1/8" to 1/4" (Over .1250 to .2500) +.0002 to -.0008 Over 1/4" to 1/2" (Over .2500 to .5000) +.0002 to -.0009 Over 1/2" to 1" (Over .5000 to 1.0000) +.0003 to -.0011 Over 1" to 3-1/2" (Over 1.0000 to 3.5000) +.0004 to -.0015 Flute Length Drill Diameter Range (inclusive) Tolerance #97 to #81 (.0059 to .0130) +1/64" to -1/64" Over #81 to 1/8" (Over .0130 to .1250) +1/8" to -1/16 Over 1/8" to 1/2" (Over .1250 to .5000) +1/8" to -1/8" Over 1/2" to 1" (Over .5000 to 1.0000) +1/4" to -1/8" Over 1" to 2" (Over 1.0000 to 2.0000) +1/4" to -1/4" Over 2" tp 3-1/2" (Over 2.0000 to 3.5000) +3/8" to -3/8" Overall Length Drill Diameter Range (inclusive) Tolerance #97 to #81 (.0059 to .0130) +1/32" to -1/32" Over #81 to 1/8" (Over .0130 to .1250) +1/8" to -1/16" Over 1/8" to 1/2" (Over .1250 to .5000) +1/8" to -1/8" Over 1/2" to 1" (Over .5000 to 1.0000) +1/4" to -1/8" Over 1" to 2" (Over 1.0000 to 2.0000) +1/4" to -1/4" Over 2" tp 3-1/2" (Over 2.0000 to 3.5000) +3/8" to -3/8" Included Point Angle Drill Diameter Range (inclusive) Included Angle Tolerance 1/16" to 1/2" (.0625 to .5000) 118* +/-5* Over 1/2" to 1-1/2" (Over .5000 to 1.5000) 118* +/-3* Over 1-1/2" to 3-1/2" (Over 1.5000 to 3.5000) 118* +/-2*	Lip Height   TIV Drill Diameter Range (inclusive)   (Total Indicator Variation) 1/16" to 1/8" (.0625 to .1250) .0020 Over 1/8" to 1/4" (Over .1250 to .2500) .0030 Over 1/4" to 1/2" (Over .2500 to .5000) .0040 Over 1/2" to 1" (Over .5000 to 1.0000) .0050 Over 1" to 3-1/2 (Over 1.0000 to 3.5000) .0060 Note: 95% of drills in any one lot to fall within tolerances above. Suggested Method of Measurement: Rotate the drill in a vee block against a back end strip. Measure the cutting lip height variation on a comparator, or with an indicator set at allocation approximately 75% of the distance from the center to the periphery of the drill. Centrality of Web   TIV Drill Diameter Range (inclusive)   (Total Indicator Variation) 1/16" to 1/8" (.0625 to .1250) .0030 Over 1/8" to 1/4" (Over .1250 to .2500) .0040 Over 1/4" to 1/2" (Over .2500 to .5000) .0050 Over 1/2" to 1" (Over .5000 to 1.0000) .0070 Over 1" to 3-1/2 (Over 1.0000 to 3.5000) .0100 Note: 95% of drills in any one lot to fall within tolerances above. Suggested Method of Measurement: Rotate the drill in a close fitting bushing. Record the difference in the indicator readings of the web at the point as the drill is indexed 180* Drill Diameter Range (inclusive) Tolerance (TIV) Actual Deviation 1/16" to 1/8" (.0625 to .1250) .0030 .0015 Over 1/8" to 1/4" (Over .1250 to .2500) .0060 .0030 Over 1/4" to 1/2" (Over .2500 to .5000) .0100 .0050 Over 1/2" to 1" (Over .5000 to 1.0000) .0140 .0070 Over 1" to 3-1/2" (Over 1.0000 to 3.5000) .0260 .0130 Note: 95% of drills in any one lot to fall within tolerances above. Suggested Method of Measurement: Place the drill in a vee block against a back end stop, and rotate it against a radial finger stop. Take an indicator reading at the leading edge of the margin on the opposite flute. Repeat for the other flute and note the difference between the two readings. The deviation in the flute spacing is equal to one-half the difference between the two readings

Drill Straightness Tolerances Drill Runout (straightness) tolerances for HSS twist drills are as follows: Jobber lengths: Fordrills smaller then .03125”, runout tolerances to be to manufacturer’s discretion. For drills .03125” and larger, runout tolerances are to be calculated per the following formula: Maximum TIR = (.0001316 X overall length/drill diameter) + .00368” Examples: Diameter Maximum TIR 1/16" .0080 1/8" .0070 1/4" .0060 3/8" .0050 1/2" .0050 Taper Lengths: For drills smaller then .03125”, runout tolerances to be to manufacturer’s discretion. For drills .03125” and larger, runout tolerances are to be calculated per the following formula: Maximum TIR = (.000375 X overall length/drill diameter) + .0027” The maximum allowable value, however, is .0200” TIR. Examples: Diameter Maximum TIR 1/16" .0200 1/8" .0180 1/4" .0120 3/8" .0090 1/2" .0090 3/4" .0080 1" .0070 1-/2" .0060 Screw Machine Lengths: For drills smaller then .0400”, runout tolerances to be to manufacturer’s discretion. For drills .0400” and larger, runout tolerances are to be calculated per the following formula: Maximum TIR = (.0001316 X overall length/drill diameter) + .00368* The maximum allowable value, however, is .0070” TIR. Examples: Diameter Maximum TIR 1/16" .0070 1/8" .0060 1/4" .0050 3/8" .0050 1/2" .0050 3/4" .0050 1" .0040 1-/2" .0040

6" Aircraft Drills: Diameter Range Maximum TIR .0400 to .0624 .0200 .0625 to .2499 .0120 .2500 to .3749 .0100 .3750 to .4999 .0070 .5000 and up .0050 12" Aircraft Drills: Diameter Range Maximum TIR .0400 to .0624 .0400 .0625 to .1934 .0350 .1934 to .5000 .0250 Taper Shank: Diameter Maximum TIR .1250 to .3749 .0150 .3750 to 1.4999 .0100 1.5000 and up .0070 Note: 95% of drills in any one lot to fall within tolerances above. Suggested Method of Measurement: Straight shank drills are to be checked with 1” of shank in a vee block with measurements taken on the margins at the point. If shank length is shorter then 1”, use the full length of shank. Taper shank drills are to be checked with the shank in a tapered vee block or a precision socket. Calculated values are to be rounded to the nearest thousandth of an inch. Tolerance on Rate of Taper for Taper Shanks The rate of taper on taper shanks is held to .0020 inch per foot in the direction which increase the rate of taper.