© 2012, 2009, 2003, Pearson Higher Education, Upper Saddle ...

1Technical Drawing with Engineering Graphics, 14/e

Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman

© 2012, 2009, 2003, Pearson Higher Education,

Upper Saddle River, NJ 07458. • All Rights Reserved.

C H A P T E R T H R E E

TECHNICAL

SKETCHING





Understanding Solid Objects-Types of Solids. Pg 62The way to beak down the object into parts that make you to draw each one easier with having all the required dimensions to comply your design. Considering relationship between parts and keep in mind the straight lines and basic curves are the basic of many objects.

Understanding Sketching Techniques-Analyzing Complex Objects. Pg 64-Points & Lines Pg 67-Angles Pg 68Before going through the free hand sketching we need to know all the Technique of drafting, concepts, how to Design object and learning how to draw those:-Points-Lines-Angled lines-Arcs-Circles & Ellipse.*Use the basic shapes as a guide to place key features. See Guitar example Pg64









CHAPTER OVERVIEW

The ability to envision three dimensional objects is an important skill for

scientist, engineers, designers, technicians and students. Learning to visualize

objects takes time and practice. Students must learn by studying technical

drawings and applying these concepts to practical applications. People who are

extraordinarily creative often posses outstanding abilities to visualize but with

practice anyone can approve their ability.

Sketching allows individuals to quickly and accurately communicate ideas.

The old saying a picture is worth a thousand words, is really true. Sketching is

an efficient way to plan your drawing and record notes needed to create a

complex object.Sketches and drawings are used to communicate or record ideas

about the shape of 3D objects.

Shaded Sketch Showing Details of Wire Placement. (Courtesy of Quantum Design.)





UNDERSTANDING SOLID OBJECTS

Three-dimensional figures are referred to as solids. Solids are

bounded by the surfaces that contain them. These surfaces

can be one of the following four Basic types:

• Planar

• Single curved

• Double curved

• Warped

Regardless of how complex a solid

may be, it is composed of combinations

of these basic types of surfaces.

Basic geometric shapes of solids are: prisms,

pyramids, cylinders, cones, spheres, tori, or ellipsoids. All three

dimensional objects are comprised of one or more of these

basic geometric shapes.

*Keep your shapes basic and simple.





Types of Solids

If the faces of a solid are equal regular polygons, it is called a regular polyhedron.

There are 5 regular polyhedron:

Solids that are bounded by plane surfaces are called as polyhedra, Pg 62-63

These Planar surfaces are also referred to as faces of the object.

- A polygon is a planar area that is enclosed by straight lines.





Prisms

A prism has two bases,

which are parallel equal

polygons, and three or

more additional faces,

which are parallelograms





Pyramids

A pyramid has a polygon for a base and triangular lateral

faces that intersect at a common point called the vertex.





Cylinders & Cones

A cylinder has a single-

curved exterior surface

A cone has a single-

curved exterior

surface





Spheres, Tori & Ellipsoids

A sphere has a double-

curved exterior surface

A torus is shaped like

a doughnut

An oblate or prolate

ellipsoid is shaped like an

egg





Viewpoint and Shading

Viewpoint: As you sketch objects, keep in mind that

you want to maintain a consistent viewpoint, like a

camera does.

Easiest sketching is when you convert object from a

book. There’s no other views will be for the object( you

can’t move around object., but you move around object

we have a multiple view point which is different and

depends on where you stand. See the rubber stand on

side as example.

Adding shading to your sketch can give it a more

realistic appearance because it represents the

way the actual object would reflect

light. And that could helps us to have idea

material type is using of object. Such as

aluminum, steel or Iron

Hatching and stippling





Edges and Vertices

EdgesAn edge of the solid is formed where two

surfaces intersect. Edges are represented in

drawings by visible or hidden lines depends

on view points.

VerticesA vertex (plural, vertices) of a solid is

formed where three or more surfaces

intersect.

Points and LinesA point is used to represent a location in space

but has no width, height, or depth.





© 2012, 2009, 2003, Pearson Higher Education, Upper Saddle ...

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