By Two-Foot Rule

To lay off any angle given in the table, open the rule at the middle until the distance between the inside corners at the knuckle joints (6-inches' mark) is equal to the distance given for that angle under Chord.

Degrees.

Chord. Inches.

5

17/32

10

1 1/32

15

1 9/16

20

2 3/32

25

2 19/32

80

3 3/32

85

3 19/32

40

4 3/32

45

4 19/32

Degrees.

Chord. Inches.

50

5 1/16

55

5 17/32

60

6

65

6 7/16

70

6 7/8

75

7 5/16

80

7 23/32

85

8 3/32

90

8 1/2

To lay off an angle greater than 90°, subtract the angle from 180°; lay out the latter angle, extending one side, so that the greater angle formed will be the one required.

By Steel Square

To lay off any angle given in the table, set either blade or tongue of the square along the line a 5, marking the 12" point at a. Mark c at a distance from b equal to that given in the table for the required angle, and draw ac; then the angle b a c will be the angle sought, approximately correct.

Laying Out Angles 208

For example, to find an angle of 30°, the distance 6 c is

Angle. Degrees.

Distance. Inches.

5

1 1/16

10

2 3/32

15

3 7/32

18° 25'

4

(J pitch roof)

20

4 3/8

22 1/2

4 31/32

25

5 19/32

26° 33'

6

(1/4 pitch)

30

6 15/16

Angle. Degrees.

Distance.

Inches.

33° 42' (1/2pitch)

8

35

8 13/32

40

10 1/16

45 (1/2 Pitch)

12

50

14 5/16

53° 7' (2/3 Pitch)

16

55

17 1/8

60

20 25/32

Taking A At The 3" Mark

65

6 7/16

67 1/2

7 1/4

(Octagon Cut)

70

8 1/4

75

11 3/16

80

17

Angle

90

abc