Autocad 3 File

UNESCO-NIGERIA TECHNICAL & VOCATIONAL EDUCATION

REVITALISATION PROJECT-PHASE II

YEAR II- SEMESTER IV

THEORY/PRACTICAL

Version 1: December 2008

NATIONAL DIPLOMA IN

MECHANICAL ENGINEERING TECHNOLOGY

AUTOCAD 3

COURSE CODE: MEC 223

UNESCO-NIGERIA TECHNICAL & VOCATIONAL EDUCATION

REVITALISATION PROJECT-PHASE II

YEAR II- SEMESTER IV

THEORY/PRACTICAL

Version 1: December 2008

NATIONAL DIPLOMA IN

MECHANICAL ENGINEERING TECHNOLOGY

AUTOCAD 3

COURSE CODE: MEC 223

TABLE OF CO NTENT

COVER PAGE

WEEK 1 1.0 REPRESENTING THE ISOMETRIC SCREW

THREADS ON DRAWINGS

1.1 Using design center in AutoCAD

1.2 Task 1

WEEK 2 2.0 REPRESENTING THE ISOMETRIC SCREW

THREADS ON DRAWING II

2.1 Using design center in AutoCAD

WEEK 3 3.0 CONVENTIONS AND SYMBOLS

3.1 Technical Drawing Abbreviations & symbols

3.2 Mechanical Parts Abbreviations & symbols

3.3 Machine Parts Abbreviations & symbols

3.4 Standard Parts Abbreviations & symbols

3.5 Quiz 1

WEEK 4 4.0 WORKING DRAWING

4.1 Introduction

4.2 Types of Working Drawings

4.3 Quiz 2

WEEK 5 5.0 ASSEMBLY DRAWING

5.1 Sequence of Producing Assembly Drawing

5.2 Task 2

WEEK 6 6.0 RULES AND FEATURES OF ASSEMBLY

DRAWING

6.1 Layout of Drawing

6.2 Part List

6.3 Dimensions

6.4 Task 3


7.1 Pin Joint Assembly


8.1 Screw Jack Assembly


9.1 Pulley Bracket Assembly


10.1 Clamp Assembly

WEEK 11 11.0 ENGINEERING DRAWING ANALYSIS

11.1 Solved Example 1

11.2 Solved Example 2

11.3 Quiz 3


12.1 Guide Bracket with Inspection Plate


13.1 Sliding Block Assembly


14.1 Machine Vice Assembly


15.1 Bracket and Glad Assembly

WEEK 1 1.0 REPRESENTING THE ISO METRIC SCREW THREADS ON

DRAWINGS

1.1 Using Design Center in AutoCAD Metric Fasteners made easier with AutoCAD, you have the access to unlimited numbers of conventions and symbols for different types of industries. You can insert and edit the convention symbols as much as you want to suite the drawing. You can log to design center from "Design Center" Command available at standard toolbar as shown below .

Once you click the design center bottom a file search window like the one below will open. From the folders list select design center, From the right window select Fasteners-Metric. Then open the block display, From block display you can select the type of fasteners you want to use.

Now let us try to select the Hex Nut -10 mm, Click the right click bottom, a short cut menu will allow you to insert the symbol with the possibility of editing it. Try to double the scale before inserting the Hex Nut, remember that the Hex Nut will be inserted as an object you can not modify it before you explode it's lines Although the drawing will not be precise after scaling, however using design library will save you time and effort (Fig. 1). Fig. 1

1.1 Task 1

1- Using AutoCAD Design Center assemble the two plates shown in (Fig. 29) use M20 for the Hex Nut & Bolt.

Fig. 1.1

2- Try to draw a 2D engineering drawing of your own and add to it as many standard parts needed (use design center).

WEEK 2 2.0 REPRESENTING THE ISO METRIC SCREW THREADS ON

DRAWINGS II 2.0 Using Design Center in AutoCAD II Using AutoCAD design center assemble the two halves of coupling shown in (Fig. 2) below, use M20 for the Hex Nut & bolt, also add suitable washers and spring washers. .

Fig. 2

WEEK 3 3.0 CONVENTIONS AND SYMBOLS Different industries use different symbols and abbreviations in their drawings, this to minimize time consumed in drawing and at the same time standardizes professional dialog and communication. 3.1 Technical drawing Abbreviations & Symbols

Table (3.1.1 & 3.1.2), explains symbols and abbreviations commonly used in engineering drawings.

Table 3.1.1

Term Abbreviation

Across flats AF

Assembly ASSY

Centers CRS Center line on a view in

a note C

CL Cylinder or cylindrical CYL

Diameter (in a note) DIA Diameter (preceding a

dimension) ø

Dimension DIM.

Drawing DRG

Figure FIG.

Long LG

Machine MC

Material MATL

Maximum MAX

Not to scale NTS

Number NO.

Radius (in a note) RAD

Radius (preceding a dimension) R Standard STD

3.2 Mechanical parts abbreviations & symbols

Table 3.1.2

3.3 Machine parts abbreviations & symbols

Table 3.1.3.

3.4 Standard parts Abbreviations & Symbols

Table 3.1.4 3.5 Quiz Sheet 1

1- Select from the right table the correct names of the conventional representations

in the left table, the first row is given as an example.

2- Select from upper table the correct abbreviation and fill the lower table.

A B C D

1 ACROSS

FLAT RADIUS SCRAPE

DIAMETER (Preceding a dimension)

2 CLEARENCE SPHERICAL LONG DRAWING

3 ASSEMBLED STATED ACROSS FACES RIGHT HAND

4 DIAMTER (in a note)

STANDARD ASSEMBLY CHAMFER

5 PLACED SPECIFICATIONS PITCH

CIRCLE DIAMETER

CENTER LINE

6

CHAMFERED

DRAWN SCREWED LIGHT GAUGE

Abbreviation

No. Abbreviation

1 AF

2 ASSY

3 ø

4 DIA

5 DRG

6 LG

7 R 8 RAD

WEEK 4 4.0 WORKING DRAWINGS 4.1 Introduction A working drawing is the final constructed drawing produced in the design stage. After that the drawing would be sent to the workshop floor for production. Thus, the drawing should be precise and drawn to an appropriate scale and it usually includes a set of the interrelated parts and details that are needed in production stage. 4.2 Types of working drawings Working drawings can be divided into two main types, they are, Assembly drawings and Detail drawings. 1) Assembly drawings A complete assembly drawing is presentation of the product or structure put together, showing all parts in their operational positions. The parts are logically connected according to the designer specifications. (Fig. 4)

Fig. 4 - Assembly drawing

2) Detailed drawings A detail drawing is used to magnify and focus on individual items in more details, this to be helpful to the shop-floor personnel in producing each part precisely, and to be in accordance with the designers requirements. (Fig.4.1)

Fig. 4.1– Detail drawing

3) Outline Assembly Drawings Usually used when general idea of exterior shape of machine or structure is required and contains only the principle dimensions (Fig. 4.2)

Fig. 4.2 - Outline Assembly Drawing

4) General Assembly Drawings It shows the general arrangement of the machine or structure having the relative positions of different parts in working order (Fig. 4.3).

Fig. 4.3 - General Assembly Drawing

5) Sub-Assembly

It is a drawing of a related group of parts and usually used to show the assembly of complicated machinery for which it would be practically impossible to show all the features on one drawing (Fig. 4.4)

Fig. 4.4 - Sub-Assembly Drawing

6) Exploded Assembly Drawing Commonly drawn in isometric, these drawings are usually useful for persons who are not trained to read Two Dimensional Drawings. (Fig. 4.5 and 4.6)

Fig. 4.5 - Exploded Assembly Drawing

. Fig. 4.6 - Exploded Drawings

QUIZ 2 4.3

1) Name three (3) types of drawing used in engineering.

• …………………..……… • ………………………….. • …………………………..

2) Name the command that is available in CAD that allows you to see all the sides of the component easily?

3) What is the main feature of an exploded drawing?

WEEK 5 5.0 ASSEMBLY DRAWINGS 5.1 Sequence of producing Assembly Drawings To be able to draw a complete assembly drawing Fig. (5) you should follow carefully the below steps:

1- Study the application of the machine or structure

2- Try to match the dimensions and understand the relationship between parts

3- Study carefully the assembly guide given to identify the relationship between parts, in case no assembly guide is given try to draw one to help you in your assembly.

Fig. 5- Assembly Guide

4- Select the suitable scale for the entire assembly drawing. 5- Draw the main part and make sure that all parts are correctly assembled.

6- Prepare the title block

7- Label each component by leader and line and number it

8- Add overall dimensions necessary for workshop production

5.2 Task 2

For the below drawing, Fig. (5.1), draw a free hand sketch of the assembly guide

Fig. 5.1

WEEK 6 6.0 RULES AND FEATURES OF ASSEMBLY DRAWING It is important that you follow some simple rules when producing an engineering drawing which although may not be useful now, will be useful when working in industry 6.1 Lay-Out of Drawing

All assembly drawings should follow a standard layout therefore interpreting and analysis will be easier

Make your own Template follow the steps below

1- Open AutoCAD New File 2- Draw a frame according to your limits (use the size of paper you are using

often) 3- Add Title Block and Parts List table, add the information shown below

4- Now save your template using save as command, change the file type to AutoCAD Drawing Template and then name your file ASSEMBLY TEMPLATE

6.2 Parts list

Each part is given a unique number, indicated on the drawing by a circle with the number in it and a leader line pointing to the part. The leader line terminates in an arrow if the line touches the edge of the component.. A table of parts should be added to the drawing to identify each part, an example of a parts list is shown below:

PART NO.

PART NAME NO. OFF

MATERIAL

6.3 Dimensions

Detailed dimensions required for manufacture are excluded from assembly drawings. But overall dimensions of the assembled object are usually indicated

Task 3 6.4

Fig (35) illustrates the details of V BLOCK ASSEMBLY, using scale 1:1 and first angle of projection draw the following:

1- An assembled sectional Front View

2- Add Title block and parts list

3- Add 8 main dimensions

Fig 6


7.1 Pin Joint Assembly The drawing below (Fig. 7) shows the details of PIN JOINT ASSEMBLY, using scale 1:1 and first angle of projection draw the following:

4- Complete Sectional Front View with all parts correctly assembled



Fig. 7

WEEK 8 8.0 ASSEMBLY DRAWING 8.1 Screw Jack Assembly The drawing below shows (Fig. 8) the details of SCREW JACK ASSEMBLY, using scale 1:1 and first angle of projection draw the following

7- Complete Sectional Front View with all parts correctly assembled



Fig.8

WEEK 9 9.0 ASSEMBLY DRAWING 9.1 Pulley Bracket Assembly The drawing below shows (Fig. 9) the details of PULLEY BRACKET ASSEMBLY, using scale 1:1 and first angle of projection draw the following

10- Complete Sectional Front View with all parts correctly assembled 11- Use Design center library to obtain the required Hexagon Nut 12- Add Title block and parts list 13- Add 8 main dimensions

Fig. 9

WEEK 10 10.0 ASSEMBLY DRAWING 10.1 Clamp Assembly The drawing below (Fig. 10) shows the parts of CLAMP, using scale 1:1 and first angle of projection draw the following:

14- Complete Sectional Front View with all parts correctly assembled 15- Side View without hidden lines 16- Use Design center library to obtain the required Hexagon Nut 17- Add Title block and parts list 18- Add 8 main dimensions

Fig. 10

WEEK 11 11.0 ENGINEERING DRAWING ANALYSIS The goal of engineering drawing is to identify the contents and elements and understand the details of the parts and objects drawn, in addition to any suggestions and modifications to be added. 11.1 Solved Example (1) The figure below (Fig. 11) shows the two views of a cylinder cover, study the drawing carefully then answer the below questions.

Fig. 11

No Questions Answer

1 For what purpose this cover is used? To close the cylinder

2 What is the pitch circle diameter of (p 10 mm, 8 holes? 90 mm

3 What is the angle between any two adjacent

holes 45

4 What is the thickness of the cover? 10 mm ,8 mm

5 What is the diameter of the dotted lines. 70 mm

6 Why are the holes located radially? Because the cover is circle

11.2 Solved Example (2) The figure below (Fig. 11.1) shows details of a screw jack, study the drawing carefully then answer the below questions.

Fig. 11.1

Question Answer

1 What is meant by M 16 x 2 M: Metric thread

16: Nominal diameter 2: thread pitch

2 What is the maximum diameter of part No. (1)? 50 mm

3 What is the total length (X)? 87 mm

4 What does U/Cut 5 x 2 in the bolt view mean? It means under-cut with 5 mm width & 2 mm depth.

5 What is the shape of the material used inside? Round bar Ø55 mm

6 What is meant by 2 / 45 ° It means chamfer operation 2 mm length & 45° angle

7 Name the internal machining operations. drilling , boring, threading, counter bore, counter-sink.

8 Name the external machining operations. parallel turning, taper, u/cut, threading, knurling.

QUIZ SHEET 3 11.3

1) The figure below Fig. (11.2) Shows the details of C-Clamp study the views carefully and answers the questions below.

Fig. 11.2

Question Answer

1 What is the maximum length of the clamped work piece?

2 What is the section of part No. 1 at X-X?

3 What is the angle of projection of part No. 3 &

No. 4?

4 Why is the type of fit between part No. 1 & No. 4?

5 What is the purpose of hole q> 6 in part No. 2?

6 What is the material required for each part ?

7 Is the true shape of surface a shown on the

drawing? If your answers NO how can you get the true shape?

The figure below Fig. (11.3) shows the details of a screw jack, study the views carefully and answer the questions below

Fig. 11.3

Question Answer

1 What is the purpose of the four grooves in the cup?

2 How can we clamp the screw to drilling hole Ø 12?

3 What is the minimum diameter of the handle that

turns the screw?

4 Why is there a gap of 3 mm at bottom of the base?

5 What is the total length of the Nut


12.1 Guide Bracket with Inspection Plate

Figure 12

Figure 12, shows a pictorial view of a guide bracket, which incorporate inspection plate. Draw full size and in correct orthographic projection the following views of the guide bracket with the inspection plate fitted into its slot:

(a) An elevation in direction of arrow A (b) A sectional elevation on plate PQ and in the direction of arrow B (c) A plan in the direction of arrow C

Show in views (a) and (c) all hidden edges and includes on your drawing six important dimensions. Either first or third angle (but not both) methods of production may be used: The method chosen must be stated on the drawing.

WEEK 13

13.0 ASSEMBLY DRAWING 13.1 Sliding Block Assembly

Figure 13

Orthographic views of a sliding block are shown in figure 13. Do not copy the views as shown but draw the following views:

(a) In place of elevation F a sectional elevation, the plane of the section and the direction of required view being indicated at XX. (b) A complete outside end elevation in the direction of arrow E. (c) A complete outside plan in the direction of arrow P and in projection with view (a).

Hidden part lines are not required on any of the views. Insert on the drawing six dimensions, the title and the scale.

WEEK 14

14.0 ASSEMBLY DRAWING 14.1 Machine Vice Assembly

Figure 14

Figure 14 shows the details of small machine vice and a key to its assembly. Draw, full size, in correct orthographic projection the following views of the completely assembled vice, the sliding jaw being approximately 25mm from the fixed jaw.

(a) A sectional elevation, in a vertical plane passing through the axis of the square threaded screw, in the direction indicated by XX in the key. (b) A plan projected from the above.

Either first angle or third angle (but not both) methods of projection may be used; the method chosen must be stated on the drawing.

WEEK 15

15.0 ASSEMBLY DRAWING 15.1 Bracket and Gland Assembly

Figure 15

Figure 15 shows the details of the parts of a bracket and gland assembly. Details drawings of the parts of a bracket and gland assembly are given in Figure 15. The studs are fitted into the holes A. The packing is then inserted into the 38mm diameter hole at D, following the gland, which is fitted so that the 11mm diameter holes pass over the projecting studs. The washers and nuts are then fitted to the studs and the nuts tightened. Do not draw the given views but make the following views, full size, of the assembly, in first angle projection:

(a) A sectional elevation, the plane of section and the direction of the required view being indicated at BB. (b) Half of a sectional elevation, the plane of section and the direction of the required view being indicated at CC. Draw that half which appears on the left of the vertical centerline (c) A half plan. Draw that half which appears above the horizontal center line, in plan.

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Autocad 3 File