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Threading theory

Thread Per Inch (TPI)

Threads per inch, commonly abbreviated as TPI,  frequently used in fasteners industry. TPI term is used to identify how many threads are there in an inch.

Thread Pitch

Thread pitch is the term used to calculate the difference between two threads. For metric fasteners, thread pitch is used in place of TPI. The distance is also measured in millimeters.To measure thread pitch a  caliper is used to measure from the peak of one thread to the next.

Thread Pitch and Threads Per Inch are both used to measure the threading of a bolt or nut to ensure that they are going to couple together properly. If different threads of  bolt and nut are used they will either seize or strip the threading resulting in an unusable connection.

 

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Weight Table
THREADING THEORY…. IN TPI & PITCH NO. 1 TO 12 AND 1/8" TO 6" IN DIMATER
Specification Table
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Thread Pitch and Thread Dimensions at Bhalla Fasteners are mentioned below

Size

Equivalent to mm

BSW

BSF

UNC

UNF

 

PITCH

 

PITCH

 

PITCH

 

PITCH

TPI

INCH

METRIC

TPI

INCH

METRIC

TPI

INCH

METRIC

TPI

INCH

METRIC

No. 1

1.854

-

-

-

-

-

-

64

0.016

0.397

72

0.014

0.353

No. 2

2.184

-

-

-

-

-

-

56

0.018

0.454

64

0.016

0.397

No. 3

2.515

-

-

-

-

-

-

48

0.021

0.529

56

0.018

0.454

No. 4

2.845

-

-

-

-

-

-

40

0.025

0.635

48

0.021

0.529

No. 5

3.175

-

-

-

-

-

-

40

0.025

0.635

44

0.023

0.577

No. 6

3.505

-

-

-

-

-

-

32

0.031

0.794

40

0.025

0.635

No. 8

4.166

-

-

-

-

-

-

32

0.031

0.794

36

0.028

0.706

No. 10

4.826

-

-

-

-

-

-

24

0.041

1.058

32

0.031

0.794

No. 12

5.486

-

-

-

-

-

-

24

0.041

1.058

28

0.036

0.907

1/8"

3.175

40

0.025

0.635

-

-

-

-

-

-

-

-

-

3/16"

4.762

24

0.041

1.058

32

0.031

0.794

-

-

-

-

-

-

1/4"

6.350

20

0.050

1.270

26

0.038

0.977

20

0.050

1.270

28

0.036

0.907

5/16"

7.938

18

0.055

1.411

22

0.045

1.154

18

0.055

1.411

24

0.041

1.058

3/8"

9.525

16

0.062

1.588

20

0.050

1.270

16

0.062

1.588

24

0.041

1.058

7/16"

11.112

14

0.071

1.814

18

0.055

1.411

14

0.071

1.814

20

0.050

1.270

1/2"

12.700

20

0.083

2.117

16

0.062

1.588

13

0.077

1.954

20

0.050

1.270

9/16"

14.288

12

0.083

2.117

16

0.062

1.588

12

0.083

2.117

18

0.055

1.411

5/8"

15.875

11

0.091

2.309

14

0.071

1.814

11

0.091

2.309

18

0.055

1.411

11/16"

17.462

11

0.091

2.309

14

0.071

1.814

-

-

-

-

-

-

3/4"

19.050

10

0.100

2.540

12

0.083

2.117

10

0.100

2.540

16

0.062

1.588

7/8"

22.225

9

0.111

2.822

11

0.091

2.309

9

0.111

2.822

14

0.071

1.814

1"

25.400

8

0.125

3.175

10

0.100

2.540

8

0.125

3.175

12

0.083

2.117

1.1/8"

28.575

7

0.143

3.629

9

0.111

2.872

7

0.143

3.629

12

0.083

2.117

1.1/4"

31.750

7

0.143

3.629

9

0.111

2.872

7

0.143

3.629

12

0.083

2.117

1.3/8"

34.925

6

0.166

4.233

8

0.125

3.175

6

0.166

4.233

12

0.083

2.117

1.1/2"

38.100

6

0.166

4.233

8

0.125

3.175

6

0.166

4.233

12

0.083

2.117

1.5/8"

41.275

5

0.200

5.080

8

0.125

3.175

-

-

-

-

-

-

1.3/4"

44.450

5

0.200

5.080

7

0.143

3.629

5

0.200

5.080

-

-

-

2"

50.800

5

0.222

5.644

7

0.143

3.629

4.5

0.222

5.644

-

-

-

2.1/4"

57.150

4

0.250

6.350

6

0.166

4.233

4.5

0.222

 
Thread Major
Diameter
Pitch Pitch
Diameter
Minor Diameter
Male Thread
Minor Diameter
Female Thread
M1 1.0 0.25 0.838 0.693 0.729
M1.1 1.1 0.25 0.938 0.793 0.829
M1.2 1.2 0.25 1.038 0.893 0.929
M1.4 1.4 0.30 1.205 1.032 1.075
M1.6 1.6 0.35 1.373 1.171 1.221
M1.8 1.8 0.35 1.573 1.371 1.421
M2 2.0 0.40 1.740 1.509 1.567
M2.2 2.2 0.45 1.908 1.648 1.713
M2.5 2.5 0.45 2.208 1.948 2.013
M3 3.0 0.50 2.675 2.387 2.459

 

Thread Major
Diameter
Pitch Pitch
Diameter
Minor Diameter
Male Thread
Minor Diameter
Female Thread
M3.5 3.5 0.60 3.110 2.764 2.850
M4 4.0 0.70 3.545 3.141 3.242
M4.5 4.5 0.75 4.013 3.580 3.688
M5 5.0 0.80 4.480 4.019 4.134
M6 6.0 1.00 5.350 4.773 4.917
M7 7.0 1.00 6.350 5.773 5.917
M8 8.0 1.25 7.188 6.466 6.647
M9 9.0 1.25 8.188 7.466 7.647
M10 10.0 1.50 9.026 8.160 8.376
M11 11.0 1.50 10.026 9.160 9.376

 

Thread Major
Diameter
Pitch Pitch
Diameter
Minor Diameter
Male Thread
Minor Diameter
Female Thread
M12 12.0 1.75 10.863 9.853 10.106
M14 14.0 2.00 12.701 11.546 11.835
M16 16.0 2.00 14.701 13.546 13.835
M18 18.0 2.50 16.376 14.933 15.394
M20 20.0 2.50 18.376 16.933 17.294
M22 22.0 2.50 20.376 18.933 19.294
M24 24.0 3.00 22.051 20.319 20.752
M27 27.0 3.00 25.051 23.319 23.752
M30 30.0 3.50 27.727 25.706 26.211
M33 33.0 3.50 30.727 28.706 29.211

 

Thread Major
Diameter
Pitch Pitch
Diameter
Minor Diameter
Male Thread
Minor Diameter
Female Thread
M36 36.0 4.00 33.402 31.093 31.670
M39 39.0 4.00 36.402 34.093 34.670
M42 42.0 4.50 39.077 36.479 37.129
M45 45.0 4.50 42.077 39.479 40.129
M48 48.0 5.00 44.752 41.866 42.857