Mechanical Engineering Drawing MECH 211/M / Lecture #1 Chapters 1 - - PowerPoint PPT Presentation

Mechanical Engineering Drawing / MECH 211/M

Lecture #1 Chapters 1 and 6 p

• Dr. John Cheung

Technical vs. Artistic Drawings

2

What makes a good technical What makes a good technical drawing?

3

What makes a good technical What makes a good technical drawing?

Should represent the concept/object clearly Does not cause any uncertainty about the

details details

Drawn in a way that reduces complexity of the

drawing drawing

Complies with standards Neat and clean Provides all information needed Well organized on the paper

4

Types of Projection Drawings

5

Two Major Projections Types

Common Parallel Projection Types

Oblique Projection Orthographic Projection Oblique Projection Orthographic Projection Isometric Projection Mult‐iview Projection

Multiview Projection

8

Position of Projections

9

Position of Projections

10

First vs. Third Angle Projection

UK used this convention. Third Angle Projection First Angle Projection

11

Object Orientation

12

Techniques for Transferring Techniques for Transferring Dimensions

13

How to Transfer Points Using Miter How to Transfer Points Using Miter Line

14

How to Transfer Points Using Miter How to Transfer Points Using Miter Line

15

How to Transfer Points Using Miter How to Transfer Points Using Miter Line

16

How to Transfer Points Using Miter How to Transfer Points Using Miter Line

Folding lines needed in the drawing.

17

Breaking the General Rules Breaking the General Rules Alternate Positions

18

Can be used for notes.

Breaking the General Rules Breaking the General Rules Partial Views

Show the importance of the Show the importance of the

• area. Detail information

specified.

19

Breaking the General Rules Breaking the General Rules Revolution Conventions

Profile view too many Too many hidden lines. Profile view – too many hidden lines, web – confusing.

20

Breaking the General Rules Breaking the General Rules Revolution Conventions

Rotate features round Rotate features round

21

Surfaces

• 1. A surface that is perpendicular to the

plane of projection it is seen as ...? (surface, edge (line), point) 2 A s rface that is parallel to the plane of

• 2. A surface that is parallel to the plane of

projection (Normal Surface) it is seen as ...? (true size, foreshortened) (surface, edge, point) g p )

• 3. A surface that is at an angle to the plane
• f projection (Oblique Surface) it is seen

as ...? (true size, foreshortened) (surface, edge point) edge, point)

22

Surfaces

• 1. A surface that is perpendicular to the

plane of projection it is seen as ...? (surface, edge, point) 2 A s rface that is parallel to the plane of

1.As a line (edge view)

• 2. A surface that is parallel to the plane of

projection (Normal Surface) it is seen as ...? (true size, foreshortened) (surface, edge, point)

2.True size surface 3 Foreshortened

g p )

• 3. A surface that is at an angle to the plane
• f projection (Oblique Surface) it is seen

as ...? (true size, foreshortened) (surface, edge point)

3.Foreshortened surface

edge, point)

23

Normal Surface and Edge

Normal Surface: A plane

surface that is parallel to a plane of projection. E.g.

Edge D

p p j g Plane A // to horizontal projection plane.

Normal Edge: A line that is Normal Edge: A line that is

perpendicular to a plane of

• projection. E.g. Edge D

Prep to profile plane of

• Prep. to profile plane of

projection, hence appears as a point 17 and true length on other planes

Profile plane of

length on other planes.

24

Profile plane of projection

Inclined Surface and Edge

• Inclined Surface: A plane surface

that is perpendicular to one plane of projection but inclined to adjacent planes. Surface A

• perp. to horizontal projection

plane – TL line 3‐5.

• Inclined Edge: Is parallel to a

plane of projection but inclined to adjacent planes. E.g. Included d B // t h i t l j ti edge B // to horizontal projection plane, hence true length in top view.

25

Oblique Surface and Edge

• Oblique Surface: A plane that is
• blique to all planes of projection

(not // to any plane, hence no true size) Surface C 25 3 6 26 in top size), Surface C 25‐3‐6‐26 in top view.

• Oblique edge: Line oblique to all

projection planes, not appear as a p j p , pp point in any view, appear FS and inclined position, e.g. Edge F, line 26‐ 25 in top view, 30‐29 in front view d 33 34 i id i and 33‐34 in side view.

• True size – rotating or draw

secondary auxiliary view Fig. 8.21.

26

A View in Isolation

This is a top view of on object. Sketch some possibilities of what this could be. One view – not enough – deep missing.

A View in Isolation

The height can vary Angled surfaces are the same as in plane

surfaces

Curved surfaces also appear the same

28

Similar Shapes in Different Views

In adjacent views the general shape will be

maintained maintained

Widths of the arms may change

29

Parallel Edges

If a series of parallel planes is intersected by

another plane the resulting lines of intersection are parallel

If two lines are parallel in a view, their If two lines are parallel in a view, their

projections in other views will be parallel

Figure 6 27 Figure 6.27

30

Cylinders Cylinders

Cylinder cut by inclined

y y plane – included surface ellipse – circle in top view. Elli d ith

Ellipses are drawn with:

– A template – Transferring many points Transferring many points and the drawing a smooth curve between h them

• Fig. 6.34

31

Next Class Topics

6.32 Intersection and Tangencies 6.33 How to Represent Holes 6.33 How to Represent Holes 6.34 Fillets and Rounds

6 35 R d

6.35 Rounds

32