American Taper Pipe Tap Specs

 

Nominal Called
Taper Pipe Tap
Size

Actual Size

Of O.D.

No. Of Threads

Per Inch

Dia. At Large

End Of

Thread Bore

L4- Length Of

External Thread

1/8"

.405

27

.350

.392

1/4"

.540

18

.457

.595

3/8"

.675

18

.592

.601

1/2"

.840

14

.732

.782

3/4"

1.050

14

.985

.794

1"

1.315

11 1/2

1.183

.985

1 1/4"

1.660

11 1/2

1.528

1.009

1 1/2"

1.900

11 1/2

1.768

1.025

2"

2.375

11 1/2

2.243

1.058

2 1/2"

2.875

8

2.682

1.571

3"

3.500

8

3.307

1.634

3 1/2"

4.000

8

3.807

1.684

4"

4.500

8

4.307

1.734

5"

5.563

8

5.370

1.840

6"

6.625

8

6.432

1.946

8"

8.625

8

8.432

2.146

10"

10.750

8

10.557

2.359

12"

12.750

8

12.557

2.559

14"

14.000

8

13.807

2.684

l6"

16.000

8

15.807

2.884

18"

18.000

8

17.807

3.084

20"

20.000

8

19.807

3.284

24"

24.000

8

23.807

3.684

 

Reference: National Bureau of Standards

W.G. 3-6-68

 

Note-

Taper of Thread = 1 in 16 measured on diameter (.0625 per 1.000)

Set lathe compound (to bore) or taper bar attachment (to chase) to 1 47 or 1 3/4

(compiled by Michael Lerke)