Chapter 5 Engineering

Working drawings

engineering drawings that are the most complete drawings produced.

Assembly drawings

Show how different parts fit together to create the entire object

Detail drawings

Show the exact and size of an object. Detail drawings provide enough information to produce the product. Detail drawings include dimensions for all parts of the product to show the overall size and shape, along with detailed features of the product.

Pictorial drawings

Show the object as it would appear to a person looking directly at the object. They are commonly used to communicate designs to people who do not understand or use orthographic drawings.

Orthographic Drawings

Use multiple views to describe the size and shape of and shape of an object. Because these drawings show many different views, they are often referred to as multiview drawings. Any three- dimensional object has six sides that can be illustrated.

Symbols

Used to represent different entities in a drawing. Symbols are used in engineering drawings to show the properties of a specific object.

Perspective drawings

Used to show an object from a specific point of view. Perspective drawings simulate what the eye see if looking at the object. One point perspective drawing uses one vanishing point. Two point perspective drawings are developed with an angle at the front of the drawing, like an isometric drawing, but instead of being drawn at set angles, the lines of both sides are drawn to a point. Three point perspective drawings use three vanishing point:one located on each side and one located above the object.

Schematic Drawings

Used to show how different parts are connected together to form a system. Schematic drawings are most commonly used for plumbing systems, electrical circuits, and production lines.

Oblique Drawings

High-light one side of an object Oblique drawings like isometric drawings, are drawn in 3-DD, but instead of using a determined angle at the front of the image, the drawing features a one side of the object as the front image.

Isometric Drawings

The most common type of pictorial drawing used.

One View Drawings

Used to show flat pieces. Usually, these flat pieces have a standard or predetermined thickness.

Engineering drawings

created to communicate products that will be manufactured.

Center lines

Are drawn using altering short and long dashes. Centerlines are used to show the center point of an object. Engineers need to show the center points of many objects including circles, arc, and ellipses

Hidden Lines

Are drawn with short dashes. Hidden lines are used to show parts of the drawing that are hidden from sight in the view that is drawn. HIdden lines may be used to show details that are cut out of the bottom of an object and lines that may be visible when you look at the object from another view.

Object lines

Are heavy and dark lines used to show the edges of the object in the drawing. Objects lines are the actual outline of the object and are the visible edges if you are viewing the 3D model of the object.

Construction Lines

Are lightly drawn lines used to lay out the drawing. They are not part of the object itself. They are merely used as reference points to help connect different pieces of the drawing. Construction lines are usually removed from the final drawing, and with the use of computer aided drafting (CAD) software, they do not appear on the final print.

Border Lines

Are the thickest and darkest lines in a drawing Border lines are used to create a border around the edges of the paper.

Industry Guidelines

Drafting practices are general guidelines. Companies develop specific guidelines for different use of line types, lettering, and the use of scale. Also included are specific guidelines for where the object is located on the page of paper. Types of drawings. The guidelines provide a list of appropriate drawings created by engineers. Listed are detail drawings, assembly drawings, schematic drawings, and many other content specific drawing types. Drawing revisions. Also included are detailed descriptions of how to make revisions to drawings. As discussed in this text, engineers often make change to drawings, and organizations outline specific procedures used to to make sure changes are documented during the process. Design references, standards, and specifications. Guideline outline the dimensioning processes, types of units used, and the types of standards, specifications, and symbols used for all company or organization design drawing. Drawing elements. There are specific guidelines for the size and format of each drawing. Included in the criteria is the proper size of paper and location of title information of the drawing. Nomenclature is the proper ways to label objects in the drawings. Included in this label are specific abbreviations to use, the proper ways to title different objects, and the requirements for listing materials for each component.

scale

Drawing may be drawn at full scale, which means all lines on the paper are identical to the size of the actual product.Full scale means 1"=1" (or 1:1). Full scale should be used if the object will fit on the paper; if not, you may use a different scale.

Three View drawings

Drawings are most commonly used for rectangular objects Complex designs require a three view orthographic drawing.

Line Types

Engineers also use different line types in drawings to highlight different parts of a design and to show features that may not appear if you were to look at a 3D model of the object. Each line type has its own characteristics, which are universally understood by engineers and manufacturers producing the object. The five primary line types are construction lines Object lines Hidden Lines Center lines Border Lines

Dimensions

Engineers use drawing to show the shape of their design and different types of lines to show features of their drawings, but they must also share the size of their drawing. Dimensioning is a process used to describe the size of the object as well as the location of different features of the design.

Two View drawings

Engineers use two view drawings to show cylindrical objects and objects with a round shape. Cylindrical objects are usually shown in two view drawings and include one view that is a circle and one view with the details from the side of an object.

There are three types of dimensions in a drawing

First, engineers use size dimensions to describe the length, width, and depth of, an object. Net, the engineers may use a location dimension to show the distance between two different features. Lastly, shape dimensions are used to provide detailed information about the shape of features.