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DRILLING | T-A® Replaceable Insert Drilling System

Tap Drill Information and Formulas | Imperial (inch)

XTP TAP TAS HPU APX 4TX REV OPN SSD ACP BTA WHL CRT ALV BRN THM

American - Unified Inch Screw Thread

Formulas 1. RPM = (3.82 • SFM) / DIA where: RPM

Probable Mean Oversize

Tap Drill Size

Decimal Equivalent

* Theo % Thread

Probable Hole Size 0.3890" 0.3936" 0.4164" 0.4249" 0.4405" 0.4561" 0.4718" 0.4874" 0.4754" 0.5030" 0.5148" 0.5186" 0.5343" 0.5499" 0.5655" 0.5739" 0.5811" 0.6124" 0.6436" 0.6526" 0.6593" 0.6749" 0.6905" 0.6920" 0.7686" 0.7843" 0.7999" 0.8155" 0.8624" 0.8936" 0.8691" 0.8780" 0.8936" 0.9093" 0.9249" 0.9405" 1.0343" 1.0499" 1.1124" 0.8780" 0.9403"

** Probable % Thread

Tap Size 7/16 - 20 7/16 - 20 1/2 - 13 1/2 - 13 1/2 - 20 9/16 - 12 9/16 - 12 9/16 - 18 9/16 - 18 5/8 - 11 5/8 - 12 5/8 - 18

= revolutions per minute (rev/min)

W 0.3860

79% 72% 87% 78% 63% 72% 87% 72% 83% 87% 70% 65% 79% 72% 87% 75% 65% 72% 84% 77% 72% 72% 77% 75% 76% 65% 84% 67% 72% 72% 82% 77% 67% 87% 72% 67% 87% 72% 76% 68% 77%

0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003" 0.003"

75% 68% 84% 75% 60% 68% 84% 69% 80% 82% 66% 61% 77% 69% 82% 75% 70% 69% 82% 75% 70% 69% 73% 71% 74% 63% 81% 64% 69% 68% 81% 75% 65% 84% 69% 64% 84% 69% 74% 65% 75%

SFM

= speed (ft/min)

25/64"

0.3906

DIA

= diameter of drill (inch)

1/2 - 13 10.5 mm 0.4134

27/64"

0.4219 0.4375 0.4531 0.4688 0.4844 0.5000" 0.5118" 0.5156" 0.5313" 0.5469" 0.5625" 0.5709" 0.5781" 0.6094" 0.6406" 0.6496" 0.6563" 0.6719" 0.6875" 0.6890" 0.7656" 0.7813" 0.7969" 0.8125" 0.8594" 0.8906" 0.8661" 0.8750" 0.8906" 0.9063" 0.9219" 0.9375" 1.0313" 1.0469" 1.1094" 0.8750" 0.9449"

2. IPM = RPM • IPR where: IPM

7/16"

29/64" 15/32"

= inches per minute (in/min)

RPM

= revolutions per minute (rev/min)

9/16 - 12 12.0 mm 0.4724

IPR

= feed rate (in/rev)

31/64"

1/2"

3. SFM = RPM • 0.262 • DIA where: SFM = speed (ft/min) RPM

9/16 - 18 13.0 mm

31/64" 17/32" 35/64"

= revolutions per minute (rev/min)

DIA

= diameter of drill (inch)

9/16"

5/8 - 18 14.5 mm

5/8 - 18

37/64" 39/64" 41/64" 21/32" 43/64" 11/16" 49/64" 25/32" 51/64" 13/16" 55/64" 57/64" 57/64" 29/32" 59/64" 15/16" 1-1/32" 1-3/64" 1-7/64" 22.0 mm 7/8"

4. Thrust

= 153,700 • IPR • DIA • K m

11/16 - 12

where: Thrust

3/4 - 10

= axial thrust (lbs) = feed rate (in/rev)

3/4 - 10 16.5 mm

IPR DIA

3/4 - 10 3/4 - 12 3/4 - 16 7/8 - 9 7/8 - 9 7/8 - 14 7/8 - 14

= diameter of drill (inch)

K m

= specific cutting energy (lbs/in 2 )

3/4 - 16 17.5 mm

5. Tool Power = .6283 • IPR • RPM • K m • DIA 2 where: Tool Power = tool power (HP) IPR = feed rate (in/rev) RPM = revolutions per minute (rev/min) K m = specific cutting energy (lbs/in 2 ) DIA = diameter of drill (inch)

15/16 - 12 15/16 - 20

1 - 8 1 - 8 1 - 8

1 - 12 1 - 12 1 - 14

Material Constants

K m (lbs/in 2 )

1-1/8 - 12 1-1/8 - 12 1-1/4 - 7

Type of Material

Hardness

Plain Carbon and Alloy

85 - 200 BHN 200 - 275 BHN 275 - 375 BHN 375 - 425 BHN

0.79 0.94 1.00 1.15 1.44 0.94 1.08 0.50 1.08 0.43 0.72 0.72 0.22 0.16

24 x 2 27 x 3

7/8"

Steel

24.0 mm

Taper Pipe Thread (NPT)

High-Temperature Alloys

-

Probable Mean Oversize

Stainless Steels

135 - 275 BHN

Tap Drill Size

Decimal Equivalent

Theo % Thread*

Probable Hole Size

Probable % Thread**

30 - 45 RC

Tap Size 1/4 - 18 3/8 - 18 1/2 - 14 3/4 - 14

Cast Iron

100 - 200 BHN 200 - 300 BHN

7/16 9/16

0.4375 0.5625 0.7031 0.9063

- - - -

0.003 0.003 0.003 0.003

0.4405 0.5655 0.7061 0.9093

- - - -

Copper Alloy

20 - 80 RB 80 - 100 RB

45/64 29/32

Titanium Alloy Aluminum Alloy Magnesium Alloy

- - -

* Based on nominal tap drill diameter ** Based on 0.003" probable mean oversize

To calculate the percent of full thread for a given hole diameter:

Basic Major Diameter of Thread - Drill Hole Size 0.0130

% Thread =

# of Thread per Inch

Notes • The above tap drill information represents probable thread percentages for the standard tap drills stocked at Allied Machine. Special insert diameters may be required in order to meet a user specific percentage of thread requirements. • The 0.003" probable mean oversize hole condition is based on optimum cutting conditions. Probable percent of full thread may vary based on less ideal cutting conditions. • The table and equations on this page are found in the Machinery’s Handbook . Permission to simplify and print the equations is granted by the editor of the Machinery’s Handbook .

www.alliedmachine.com | 1.330.343.4283

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