Introduction to Graphics Communication By: Dr Hamid Ullah Khan Niazi Engineering Drawing Introduction to Graphics Communication By: Dr Hamid Ullah Khan Niazi

Lecture Outline Introduction Standard for drawing sheet Media Alphabet of lines Scale Next class

Introduction Engineers: People who use technical means to solve problems. They design products, systems, devices, and structures to improve our living conditions Technical Drawings: a clear, precise language used in the design process for communicating, solving problems, quickly and accurately visualizing objects, and conducting analyses A graphical representation of objects and structures is done using freehand, mechanical, or computer methods

HISTORY The earliest known technical drawing was created about 4000 BC. The first written evidence of technical drawings dates to 30 BC. In 1876, the blueprinting machine was developed. From about 1750, when Gaspard Monge developed descriptive geometry practices/ By about 1900, most drawings were created using first-angle projection. Starting in the late nineteenth century, most companies in the United States switched to third-angle projection. Third-angle projection is considered a more logical or natural positioning of views.

Media Media: surfaces upon which an engineer or technologist communicates graphical information. Different types include: Tracing paper (a thin, translucent paper used for detail drawings) Vellum (tracing paper chemically treated to improve translucency) Polyester film (transparent, waterproof, and difficult to tear, “Mylar”) The American National Standard Institute (ANSI) has established standard sheet sizes and title blocks for media used in technical drawings

Standard for Drawing Sheet

Standard for Drawing Sheet (con’t)

Types of line Long Break Lines • Long, thin lines. • Used to show that the middle section of an object has been removed so it can be drawn on a smaller piece of paper. Short Break Lines • Thick wavy line. • Used to break the edge or surface of a part for clarity of a hidden surface.

ASME Y14 standards The following are ASME Y14 standards that are basic engineering drawing standards: ASME Y14.1, Decimal Inch Drawing Sheet Size and Format ASME Y14.1M, Metric Drawing Sheet Size and Format ASME Y14.2, Line Conventions and Lettering ASME Y14.3, Orthographic and Pictorial Views ASME Y14.5, Dimensioning and Tolerances ASME Y14.24, Types and Applications of Engineering Drawings ASME Y14.34, Associated Lists ASME Y14.35M, Revision of Engineering Drawings and Associated Documents ASME Y14.36M, Surface Texture Symboles ASME Y14.38, Abbreviations and Acronyms for Use on Drawings and Related Documents ASME Y14.41, Digital Product Definition Data Practices ASME Y14.100, Engineering Drawing Practices All other ASME Y14 standards are considered specialty types of standards and contain additional requirements or make exceptions to the basic standards as required to support a process or type of drawing.

Alphabet of lines

Phantom Line Phantom Lines • Thin lines made up of long dashes alternating with pairs of short dashes.

Break Line A break line saves drawing space by eliminating unnecessary length.

Introduction (con’t) 92% of the design process is graphical The remaining 8% is mathematics and written communication Breakdown of Engineer’s time Who uses engineering graphics?

Introduction (con’t) Practice Exercise 1.1 Attempt to describe the part shown in this figure verbally to the person seated next to you Fig. 1.89 How easy is it to describe a part such as this without the use of graphics?

Drawing Tools (1.8) 5 Pencils with grades – HB and H, or F and 2H and 3 H combinations One compass and one divider One set of 45- and 30/60-degree triangles One T-square (With English unit on one side and Metric unit on other side) One irregular curve (French curve) One protractor One good eraser (and if you can afford, one erasing shield)

Drawing Tools (con’t) The use of drafting tools

Alphabet of Lines Pencil Grades Line Weight Remember that Accuracy, Neatness, and Speed count in technical drawing

Alphabet of lines (con’t)

Type of Projection

Next Lecture Purchase drafting tools needed for manual drafting portion of class if you have not done so Read the topics on Lines and lettering