Fig. 39. Correct Method of Indicating Shop Rivets.

Notation Used. As stated before, the feet and inches should always be given when a multiple space is given. For example they should be written thus:

5 @ 6"=3'-0"

2 @ 3"=0'-6"

7 @ 4"=2'-4"

In single dimensions less than 1 foot it is not necessary to state the 0 for the foot, and, therefore, we have for example 4", 6", 11", etc., up to and including 12". A dash should always be placed between the feet and inches as shown above. Careful attention should be paid to this detail since the omission of the dash may cause the dimensions to be considered as all feet or all inches and time and money will accordingly be lost.

In material notation the following are the rules: For angles the number should be placed first, the angle sign second, the dimension of the greatest leg next, then the small leg, then the thickness, and then the length in feet and inches. For example,

For plates the number comes first, the abbreviation next, the width in inches next, then the thickness in inches, and finally the length in feet and inches.

For example,

For beams and channels the number is stated first, next the depth in inches, then the weight in pounds per foot, then the sign, and finally the length in feet and inches.

For example,

Zee bars are designated by their depth and thickness. The number is written first, the depth next, then the thickness, then the sign and finally the length in feet and inches.

## Table V. Dimensions And Conventional Representation Of Rivets

For example,

Bars are designated by their number, then their size, or diameter and finally their length in inches. For example,

Rivets and Rivet Spacing. Rivets are made in various sizes and are spoken of according to the diameter of their shank. Thus a 7/8-inch rivet is one which has its shank J inch in diameter. The heads of the rivets are not perfect hemispheres, being less in height than one half the diameter of the head. Table V gives the dimensions of rivets of various diameters and their conventional representation in detail drawings. These dimensions are desirable on the drawings since they are often necessary in order to so figure the work that the material will not strike the heads. Rivets smaller than 3/4 inch are seldom used except where the size of the material requires it. Rivets larger than 7/8 inch in diameter are seldom used except in the heaviest work; and the beginner is advised not to use them until he has permission from those above him in charge.

Rivets should not be placed so close that the material between them is unduly injured by pushing or that the driving tool or "dolly" will interfere with one rivet when driving the other; likewise they should not be placed so far apart that the material between them will separate or open up. Unless specified otherwise in the specifications Table VI may be taken as good practice; for 3/4-inch, 7/8-inch, and 1-inch rivets, the minimum spacing is seen to be three diameters of the rivet.

## Table VI. Minimum Rivet Spacing

(All dimensions given in inches)

 Size of Rivets 1/4 3/8 1/2 5/8 3/4 7/8 1 Minimum Spacing Center to Center 1 1 1/4 1 3/4 2 2 1/4 2 5/8 3

The maximum spacing allowable is usually sixteen times the thickness of the thinnest plate they go through. The minimum and maximum limits placed above are not to be used wherever possible. Few engineers consider it advisable or permit spacings less than 2 1/2 inches and 3 inches, or more than 4 inches and 5 inches for 3/4-inch and 7/8-inch rivets, respectively.

The minimum limits above refer to the center to center of rivets, while the maximum values refer to the distance center to center measured along the gauge line or line along which the rivets are placed.

Fig. 40. Angles with Gauge Line.

Gauge lines may be single, Fig. 40a, or double as in Fig. 40b.

The gauge of a shape is the distance of the gauge line from a certain base. In the angle it is the back, in the channel it is the back, while in the I-beam it is the bisecting line of the web.

The gauges for standard channels and l-beams are given in the handbooks of manufacturers, such as Cambria, Carnegie, etc., which books also give the size of rivet or bolt which can be used in the flange of any certain I-beam or channel. This does not mean that the size of bolt or rivet there given must be used in the web also, in fact, 3/4-inch and 7/8-inch should be used in the web, no matter what size is specified for the flange. The standard gauges for angles are given in Table VII.

While a double gauge is shown for a 5-inch leg, it is very undesirable to use it. Do not use 5-inch legs with double gauge lines. Likewise, do not use a single-gauge line on an angle with a 6-inch leg or more, unless specially told to do so by those higher in authority.

Fig. 41. Section Showing Crimped Angle, Chord Angle, and Web.

## Table VII. Standard Gauges For Angles

(All dimensions given in inches)

*When thickness is 3/4 inch or over.

In the spacing of rivets in crimped angles, the distance "b", Fig. 41, should be 1 1/2 inches plus twice the thickness of the chord angles, but never less than 2 inches.

The grip of a rivet is the length under heads after the rivet has been driven. The length of a rivet is the length of the shank before the rivet is driven, Fig. 42, these lengths for various grips being easily found in any manufacturer's handbook.