Mechanical drawing

Author: Chief Editor: Zhang Fangjin
Publisher:
Publishing Date: 2000-05-01
Features: Dimensioning, projection drawing, methods of expressing the shape of machine parts, assembly drawings, etc. This book is a training textbook for intermediate-level workers in various mechanical manufacturing trades participating in vocational skill appraisals, and can also serve as a teaching reference for technical schools and vocational schools.
Excerpt:
Chapter Basic Knowledge of Technical Drawing
Training Requirements: Be familiar with the relevant provisions in the "National Standard for Technical Drawing" and correctly use drawing tools while mastering the basic methods of geometric construction.
Section Basic Drawing Standards
1. Drawing Sheet Size and Format (GB/T14689—93)
1. Drawing Sheet Size: When drawing mechanical drawings, priority should be given to the basic sheet sizes specified in Table 1-1.
2. Title Block Format: A title block must be drawn on the drawing sheet using a thick solid line. The format is divided into two types: without binding edge and with binding edge, as shown in Figures 1-1 and 1-2. The size of the title block should be in accordance with the specifications in Table 1-1. Every drawing sheet must have a title block. The title block should be located in the lower right corner of the drawing sheet. The outer frame line of the title block should be drawn using a thick solid line, and its right and bottom edges should coincide with the frame lines of the drawing sheet. The direction of viewing the drawing should be consistent with the direction of viewing the title block.
2. Scale (GB/T14690—93)
The term "scale" refers to the ratio of the linear dimensions of corresponding elements in the drawing to those of the actual object. A ratio of 1 is called the original scale, i.e., 1:1. A scale greater than 1 is called an enlarging scale, such as 2:1. A scale less than 1 is called a reducing scale, such as 1:2. Figures drawn with different scales are shown in Figure 1-3.
1. Scale Series: When drawing drawings to scale, appropriate scales should be selected from the scale series specified in Table 1-2 in priority.