Diameter in inches. . . .

1/4

5/16

3/8

7/16

1/2

9/16

5/8

3/4

7/8

1

Threads per inch..........

20

18

16

14

13

12

11

10

9

8

Diameter in inches. .. .

1 1/8

1 1/4

1 3/8

1 1/2

1 5/8

1 3/4

1 7/8

2

2 1/4

2 1/2

Threads per inch..........

7

7

6

6

5 1/2

5

5

4 1/2

44

4

Diameter in inches....

2 3/4

3

3 1/4

3 1/2

3 3/4|

4

4 1/4

4 1/2

44

5

Threads per inch..........

4

3 1/2

3 1/2

3 1/4

3

3

2 7/8

2 3/4

2 5/8

2 1/2

Diameter in inches . .

5 1/4

5 1/2

5 3/4

6

Threads per inch..........

2 1/2

2 3/8|

2 3/8

2 1/4

Angle of threads = 60°. Flat surface at top and bottom = 1/8 of the pitch. For rough bolts, the distance between parallel sides of bolt-head and nut = 1-1/2 diameters of bolt + 1/8 of an inch. Thickness of head = 1/2 distance between parallel sides. Thickness of nut = diameter of bolt. In finished bolts, thickness of head = thickness of nut. Distance between parallel sides of a bolt-head and nut and thickness of nut is 1/16 of an inch less for finished work than for rough.