Graph paper is provided at the end of this review for your use. Refer to the drawing, Bearing Support Bracket, page 36. 1. What scale size is used? 11. List the types of lines found on the print. 2. With reference to the above scale, what linear length on the drawing represents a dimension of […]

Basic size refers to the base size of a part to which a tolerance value is applied. For example, in Figure 4.23, the basic size dimension is 2.00 with a tolerance of ± .06. Actual size refers to the size of the part when measured. Nominal size refers to a dimension that represents an approximate […]

There are two basic methods for dimensioning a part: conventional dimensioning and baseline dimensioning. The conventional method of dimensioning is illustrated by Figure 4.21. In this method, the overall dimen­sions of length, width, and height are given. Dimensions A and B are not given because they are easily found by adding the given dimensions. If […]

FIGURE 4.17 ■ External thread symbols. Weldments very often include threaded parts. Standard thread symbols are used on prints to represent threaded parts. Figure 4.17 shows how external threads are represented. Internal threads (tapped holes) are represented by the symbols shown in Figure 4.18. FIGURE 4.18 ■ Internal thread symbols. An internal thread can be […]

Tolerance is another important element of dimensioning. It is a figure (or figures) given as a plus (+) or minus (—) quantity that allows for a variation in the dimension to which it is applied. It specifies the amount of error allowed when making a part. Any or all of the fractional, decimal, or angular […]

Several other types of round holes found on weldment fabrication drawings are counterbored, countersunk, spotfaced, and counterdrilled holes. The methods, abbreviations, and symbols used for dimensioning these holes are shown in Figure 4.11, Figure 4.12, Figure 4.13, Figure 4.14, and Figure 4.15. Note that the abbreviation DP or the symbol for depth is applied to […]

Drilled hole dimensions are shown by the use of a leader and a note. These are usually applied to the view that shows the shape of the hole. The note gives the size of the drill, the number of holes to be drilled, and may also give the depth to which the holes are to […]

When the ends or corners of an object are to be rounded, a radius, arc, or curve is shown and is dimensioned by one of several methods, as shown in Figure 4.8. The methods of dimensioning include the use of an angu­lar dimension and its radius (Figure 4.8a); two linear dimensions that indicate where the […]

PURPOSE OF DIMENSIONS Dimensions serve two important purposes: 1. They give the sizes needed to fabricate the part. 2. They indicate the locations where components of the part should be placed, assembled, machined, or welded. Figure 4.1 illustrates the meaning of size and location dimensions. Note that linear dimensions used on a print may be […]

FIGURE 3.1 ■ Application of a local note. In many cases, it is not possible to give all the information needed on a print by the combined use of lines and dimensions. To provide additional information, notes and specifications are used. A note is lettered information (in capital letters) concerning the details of construction. The […]