aed lab

AIRCRAFT ENGINEERING DRAWING

LABORATORY MANUAL

B.TECH

(II YEAR – I SEM)

(2015-16)

Prepared by:

Mr. S.SHAILESH BABU, Assistant Professor

Mr. M.YUGENDAR, Assistant Professor

Department of Aeronautical Engineering

MALLA REDDY COLLEGE

OF ENGINEERING & TECHNOLOGY (Autonomous Institution – UGC, Govt. of India)

Recognized under 2(f) and 12 (B) of UGC ACT 1956

Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC – ‘A’ Grade - ISO 9001:2008 Certified)

Maisammaguda, Dhulapally (Post Via. Hakimpet), Secunderabad – 500100, Telangana State, India

Department of ANE AED LAB MANUAL

CONTENTS

1. INTRODUCTION to CAD

2. ACAD – BASICS

2.1 Starting with ACAD

2.2 Layout and sketching

2.3 Drawing environment

2.4 Elements of drawing

2.4.1 Draw commands

2.5 3D functions

2.6 Starting the drawing

2.6.1 Drawing sheet layout -1

2.6.2 Drawing sheet layout - 2

3. 2D – FIGURES USING ACAD

4. ISOMETRIC DRAWINGS USING ACAD

5. 3-D FIGURES USING ACAD

6. INTRODUCTION TO CREO 2.0


PROGRAMME EDUCATIONAL OBJECTIVES

PEO1: PROFESSIONALISM & CITIZENSHIP

To create and sustain a community of learning in which students acquire

knowledge and learn to apply it professionally with due consideration

for ethical, ecological and economic issues.

PEO2: TECHNICAL ACCOMPLISHMENTS

To provide knowledge based services to satisfy the needs of society and

the industry by providing hands on experience in various technologies in

core field.

PEO3: INVENTION, INNOVATION AND CREATIVITY

To make the students to design, experiment, analyze, interpret in the

core field with the help of other multi disciplinary concepts wherever

applicable.

PEO4: PROFESSIONAL DEVELOPMENT

To educate the students to disseminate research findings with good soft

skills and become a successful entrepreneur.

PEO5: HUMAN RESOURCE DEVELOPMENT

To graduate the students in building national capabilities in technology,

education and research.


CODE OF CONDUCT FOR THE LABORATORIES

All students must maintain the Dress Code.

Sandals or open-toed shoes are NOT allowed.

Foods, drinks and smoking are NOT allowed.

All bags must be kept in the racks provided.

The lab timetable must be strictly followed.

Be PUNCTUAL for your laboratory session.

Experiment must be executed within the given time.

Should maintain silence in the lab during laboratory session.

Keep the lab premises clean.

Handle machines with care.

All students are liable for any damage to the accessories due to

their own negligence.

All tools must be RETURNED if you taken from the lab supervisor.

Students are strictly PROHIBITED from taking out any items from

the laboratory.

Students are NOT allowed to work alone in the laboratory without

the Lab Supervisor

Report immediately to the Lab Supervisor if any malfunction of the

accessories is there.

Before leaving the lab

Place the chairs properly.

Turn off the switches.

Please check the laboratory notice board regularly for updates.


1. INTRODUCTION

Computer Aided Drafting is a process of preparing a drawing of an object on the screen of a

computer. There are various types of drawings in different fields of engineering and sciences. In the

fields of mechanical or aeronautical engineering, the drawings of machine components and the layouts

of them are prepared. In the field of civil engineering, plans and layouts of the buildings are prepared. In

the field of electrical engineering, the layouts of power distribution system are prepared. In all fields of

engineering use of computer is made for drawing and drafting.

The use of CAD process provides enhanced graphics capabilities which allows any designer to

Conceptualize his ideas

Modify the design very easily

Perform animation

Make design calculations

Use colors, fonts and other aesthetic features.

REASONS FOR IMPLEMENTING A CAD SYSTEM

1. Increases the productivity of the designer: CAD improves the productivity of the designer to

visualize the product and its component, parts and reduces the time required in synthesizing,

analyzing and documenting the design

2. Improves the quality of the design: CAD system improves the quality of the design. A CAD

system permits a more detailed engineering analysis and a larger number of design alternatives

can be investigated. The design errors are also reduced because of the greater accuracy provided

by the system

3. Improves communication: It improves the communication in design. The use of a CAD

system provides better engineering drawings, more standardization in the drawing, and better

documentation of the design, few drawing errors and legibility.

4. Create data base for manufacturing: In the process of creating the documentation for these

products, much of the required data base to manufacture the products is also created.

5. Improves the efficiency of the design: It improves the efficiency of the design process and the

wastage at the design stage can be reduced.


APPLICATION OF CAD:

There are various processes which can be performed by use of computer in the drafting process.

1. Automated drafting: This involves the creation of hard copy engineering drawings directly

from CAD data base. Drafting also includes features like automatic dimensioning, generation of

cross – hatched areas, scaling of the drawing and the capability to develop sectional views and

enlarged views in detail. It has ability to perform transformations of images and prepare 3D

drawings like isometric views, perspective views etc.,

2. Geometric modeling: concerned with the computer compatible mathematical description of the

geometry of an object. The mathematical description allows the image of an object to be

displayed and manipulated on a graphics terminal through signals from the CPU of the CAD

system. The software that provides geometric modeling capabilities must be designed for

efficient use both by computer and the human designer.

BENEFITS OF CAD:

The implementation of the CAD system provides variety of benefits to the industries in design

and production as given below:

1. Improved productivity in drafting

2. Shorter preparation time for drawing

3. Reduced man power requirement

4. Customer modifications in drawing are easier

5. More efficient operation in drafting

6. Low wastage in drafting

7. Minimized transcription errors in drawing

8. Improved accuracy of drawing

9. Assistance in preparation of documentation

10. Better designs can be evolved

11. Revisions are possible

12. Colors can be used to customize the product

13. Production of orthographic projections with dimensions and tolerances

14. Hatching of all sections with different filling patterns


15. Preparation of assembly or sub assembly drawings

16. Preparation of part list

17. Machining and tolerance symbols at the required surfaces

18. Hydraulic and pneumatic circuit diagrams with symbols

19. Printing can be done to any scale

LIMITATIONS OF CAD

1. 32 – bit word computer is necessary because of large amount of computer memory and time

2. The size of the software package is large

3. Skill and judgment are required to prepare the drawing

4. Huge investment

CAD SOFTWARES

The software is an interpreter or translator which allows the user to perform specific type of

application or job related to CAD. The following softwares are available for drafting

1. AUTOCAD

2. Pro – E

3. CATIA

4. MS OFFICE

5. PAINT

6. ANSYS

7. MSc.NASTRAN

8. IDEAS

9. SOLID WORKS

10. HYPERMESH

11. FLUENT – GAMBIT

The above softwares are used depending upon their application.

AUTO CAD

Auto CAD package is suitable for accurate and perfect drawings of engineering designs. The

drawing of machine parts, isometric views and assembly drawings are possible in AutoCAD. The

package is suitable for 2D and 3D drawings.


2. AutoCAD – BASICS

2.1 STARTING WITH ACAD

CAD uses four basic elements for preparation of any drawing:

1. Line

2. Curves

3. Text

4. Filling point.

Computer Aided Drafting is done by the operator by placing the mouse pointer by placing the

mouse pointer at the desired location and then executing the command to draw the graphic elements

using different methods.

Advanced computer aided drafting packages utilize four areas on the screen.

1. Drawing Area

2. Command Area

3. Menu Area

4. Tool boxes.

2.2 LAYOUT AND SKETCHING

The package provides various facilities for layout, sketching and borders for preparing a

drawing. It provides facilities for display co-ordinates and measurement units.

a. Units: The format for display co – ordinates and measurement can be selected according to the

requirement.

Several measurement styles are available in ACAD. The main methods are engineering and

architectural, having specific base unit assigned to them.

i. Decimal: select to enter and display measurements in decimal notation

ii. Engineering: Display measurements in feet and decimal inches.

iii. Architectural: Display measurements in feet, inches and fractional inches

iv. Fractional: Display measurements in mixed numbers notation

v. Scientific: Display measurements in scientific notation.


The precision that is specified controls the number of decimal places or fractional size to which

we want linear measurements displayed.

b. Angles: Select the format in which we want to enter and display angles.

i. Decimal Degrees: Display partial degrees as decimals

ii. Deg/Min/Sec: Display partial degrees as minutes and seconds.

iii. Grades: Display Angles as grades

iv. Radians: Display angles as radians.

v. Surveyor: Displays angles in surveyor units.

c. Angle measure: Select the direction of the zero angle for the entry of angles:

i. East: Select to specify the compass direction east as the zero angles.

ii. North: Select to specify the compass direction north as the zero angles.

iii. West: Select to specify the compass direction west as the zero angles.

iv. South: Select to specify the compass direction south as the zero angles.

v. Other: Select to specify a direction different from the points of the compass as the zero

angles.

d. Area: Enter the approximate width and length which is planned to draw in full scale units. This

limits the area of the drawing covered by grid dots when the grid is turned on. It also adjusts

several default settings, such as text height, line type scaling and snap distance to convenient

values. It is possible to adjust these settings.

e. Title block: Select the description of an ACAD drawing file of a title block to insert as a symbol

in the new drawing. It can add or remove drawing files of title blocks from the list with the Add

or Remove buttons

f. Layout: Paper space is often used to create complex multiple view drawings. There are three

types of paper spaces:

1. Work on the drawing while viewing the layout.

2. Work on the drawing without the layout visible

3. Work on the layout of the drawing.


The following procedure is used for this purpose

1. From the File menu or from the standard tool bar, choose New

2. In the start up dialog box, choose Use a wizard, and select Advanced wizard

3. Choose OK

4. In the Advanced Setup Dialog box, select Title Block.

5. Select Title Block Description and Title Block file Name from the lists and then choose Add.

6. In the Select Title Block File dialog box, Select a title block, then choose open

7. In the Advanced Setup dialog box, a sample of that title is displayed.

8. Choose Done.

2.3 DRAWING ENVIRONMENT

ACAD provides two drawing environments for creating and laying out the drawing.

i. Model Space

ii. Paper Space.

ACAD allows creating drawing, called a model, in full scale in an area known as model space

without regard to the final layout or size when the drawing is plotted on the paper.

In the space opened for the first time, it is possible to create floating viewports to contain

different views of the model. In the paper space, floating viewports are treated as objects which can be

moved and resized in order to create a suitable layout.

LIMITS

This sets and controls the drawing boundaries.

At the command prompt, enter limits

ON/OFF/<LOWER LEFT CORNER> <current>: Specify a point, enter on or off, or press

enter.


LTSCALE

This sets the line type scale factor. Use LTSCALE to change the relative length of the dash – dot

line types per drawing unit

At the Command prompt, enter ltscale

New scale factor <current>: Enter a positive real value or press enter

Changing the line type scale factor causes the drawing to regenerate.

MEASURE

This places point objects or blocks at measured intervals on an object.

At the command prompt, enter measure

Select object to measure: Use an object selection method <segment length> / Block: Specify

a distance.

PAN

This moves the drawing display in the current viewport.

At the command prompt, enter pan

Displacement: Specify a point (1)

The point which specify indicates the amount to move the drawing or the location of the drawing

to be moved.

Second point: Press or specify a point (2)

If pressed, ACAD moves the drawing by the amount which is specified in the Displacement

prompt. If we specify a point, ACAD moves the location of the drawing to that point.


2.4 ELEMENTS OF DRAWING

2.4.1 DRAW COMMANDS

LINE:

A line is specified by giving its two end points or first point and the distance of line along with

its angle of inclination. A line can be drawn by using two commands.

Command: line

Specify first point: Specify a point (1)

Specify next point or [Undo]: Specify a point (2)

The second point can be indicated by @d<a

Where d is the distance of line and a is the angle of inclination in degrees.

PLINE:

This is a poly line which allows continuous segment of the line and it is drawn similar to the line

command. The polyline allows changing the thickness of the line according to the requirement.

From the Draw tool bar choose the Polyline flyout.

Draw pull down menu: Polyline

At the command prompt, enter pline

Syntax

Specify start point: Specify a point (1)

Current line-width is <current>

Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: Specify a point (2) or enter an

option


LINETYPE

Creates, loads, and sets linetypes. The LINETYPE command defines line characteristics

consisting of dashes, dots, and spaces.

Format menu: Linetype or Command line: linetype

1. CURVES

Following are the various types of curves used in the drawings:

i. Circle

ii. Ellipse

iii. Arc

iv. Regular or any other type.

i. Circle: The circle can be drawn by using two types of commands

a. Circle

b. Donut


a. CIRCLE: This command draws the circle by using four methods:

Center point and radius

Two point circle

Three point circle

Tangent circle

At the command prompt, enter circle

Specify center point for circle or [3P (Three Points)/2P (Two Points)/Ttr]: Specify a point

or enter an option

b. DONUT: This draws filled circles and rings.

Donuts are constructed of a closed polyline composed of wide arc segments.

At the command prompt, enter donut

Specify inside diameter of donut <current>: Specify a distance or press ENTER

If you specify an inside diameter of 0, the donut is a filled circle.

Specify outside diameter of donut <current>: Specify a distance or press ENTER

Specify center of donut or <exit>: Specify a point (1) or press ENTER to end the command

ii. ELLIPSE: It is a curve having major and minor axis with a center.

The ellipse can be prepared by four methods.

Axis endpoint

Arc

Centre

Iso circle


Axis end point: Defines the first axis by two specified endpoints. The angle of the first axis

determines the angle of the ellipse. The first axis can define either the major or the minor axis of

the ellipse.

Arc: Creates an elliptical arc. The angle of the first axis determines the angle of the elliptical arc.

The first axis can define either the major or the minor axis of the elliptical arc.

Center: Creates the ellipse by a specified center point.

Isocircle: Creates an isometric circle in the current isometric drawing plane.

At the command prompt, enter ellipse

iii. ARC: The arc is a curve specified by center and radius as well as the start angle and end angle.

There are seven method used for drawing an arc.

1. Three point method

2. Start point-center point –end point

3. Start point-center point-length of chord

4. Start point-end point –angle of inclusion

5. Start point-end point-direction

6. Start point-center point-angle of inclusion

7. Start point-end point-radius

2. Drawing of Rectangle: A rectangle can be drawn by LINE command or by Rectangle

command. The PLINE command also allows for drawing of hollow or filled rectangle .A

SOLID command is also used for drawing of filled rectangles.


1. RECTANGLES: draws a rectangular polyline

At the command prompt, enter rectangle

First corner: specify point (1)

Other corner: specify point (2)

2. SOLID: creates solid –filled polygons .solids are filled only when fill system variable is set

to on view is set to plan.

At the command prompt, enter solid

First corner: specify point (1)

Other corner: specify point (2)

The first two points define one edge of the polygon.

Third point: specify a point (3) diagonally opposite the second

Forth point: specify a point (4) or press enter

3. DRAWING OF POLYGON

Creates an equilateral closed polyline .A polygon is a polyline object. AUTOCAD draws

polyline with zero width and no tangent information.

At the command prompt enter polygon

Number of sides <current>: enter a value between 3 and 1024 or press enter

Edge/<center of polygon>: specify a point (1) or enter.

4. POINT

Creates a point object .points can act as nodes to which you can snap objects .you can specify a full

3D location for a point.


At the command prompt, enter point

Point: specify a point

5. ERASING OF OBJECT:

The object can be removed or erased by use of erase command

ERASE

This removes object from drawing

At the command prompt, enter erase

Select objects: use an object selection method.

6. COLOURING OF OBJECT:

The object can be drawn with any variety of colour which ranges from 0 to 256.

The setting of colour can be done by color command

COLOR

Sets the colour for new objects.

At the command prompt, enter color <current>: enter a value (1-255), color name, by block, or by

layer

7. FILLING OF OBJECT: the object can be filled with different colors and patterns by use of

hatch command

This command allows selection of various patterns, scale of pattern and angle of pattern.

HATCH

This fills an area with a pattern.

HATCH fills the specified hatch boundary with non-associative hatch


A non –associative hatch is not updated when its boundaries are modified .a hatch boundary consists

of an object or objects that completely enclose an area

At the command prompt, enter hatch

Pattern (? Or name/ U, style) <current>: enter a predefined pattern name, enter u, enter? Or press

enter.

8. SCALING OF DRAWING: zoom command displays the object at a specified scale factor. the

value entered is relative to the limits of the drawing .for example ,entering 2 doubles the apparent

display size of any objects from what it would be if it were zoomed to the limits of the drawing

If you enter a value followed by xp, auto CAD specifies the scale relative to paper scale unit’s

.for example, entering 0.5xp displays model space at half the scale of paper space unit’s .the

following illustration shows a number of viewports arranged in paper space. the view in each

view port is scaled relative to paper space .the first view is scaled 1=1 relative to paper space

(1xp) ,the second is scaled 0.5=1 relative to paper space (0.5xp),and so on.

ZOOM

This increases or decreases the apparent size of objects in the current view port

At the command prompt, enter zoom

All/center/dynamic/extents/left/previous/vmax/window/<scale(x/xp)>: enter an option or

value, specify a point, or press enter

9. TEXT: The text in software is indicated by font’s .the fonts define the shapes of the text

characters that make up each character set. In AUTOCAD, you can use true type fonts in

addition to AUTOCAD’s own compiled shape (SHX) fonts.

A font is indicated by various parameters like

i. Style :these are four types: normal,bold,italic,underline

ii. Size: this is the size of characters


iii. Colour: there are facilities to colour the characters selecting layer.

iv. Type: different types of fonts may be used:

Mono text: COMPUTER AIDED DESIGN

Romans: COMPUTER AIDED DESIGN

Romand: COMPUTER AIDED DESIGN

Dtext: This displays text on the screen as it is entered .AutoCAD can create text with a variety

of character patterns, or fonts. These fonts can be stretched, compressed, oblique, mirrored, or

aligned in a vertical column by applying a style to the font .text can be rotated, justified, and

made any size.

At the command prompt, enter text

Justify/style/<start point>: specify a point or enter an option

TEXT: This creates a single line of text .AutoCAD can create text with a variety of character

patterns, or fonts. These fonts can be stretched, compressed, oblique, mirrored, or aligned in a

vertical column by applying a style to the font.


Justify/style/<start point>: specify a point or enter an option

QTEXT: This controls the display and plotting of text and attribute of objects.


ON/OFF <current>: enter on or off, or press enter

10. TRANSFORMATIONS: These are the modifications in the drawn objects.

There are different types of transformations used


1. MOVE: This allows to move or displace objects a specified distance in a specified direction

At the command prompt, enter move

Select objects: use an object selection method

Base point or displacement: specify a base point (1)

Second point of displacement: specify a point (2) or press enter

2. COPY: This is used for producing a duplicate copy of the drawing.

At the command prompt, enter copy


<Base point or displacement >/multiple: specify a base point (1)

For a single copy or enter m for multiple copies

3. ROTATE: It moves objects about a base point

At the command prompt, enter rotate


<Rotate angle >/reference: specify an angle or enter r

4. STRETCH: This moves or stretches objects .AutoCAD stretches lines, arcs, elliptical arcs,

splines, rays and polyline segments that cross the selection window.

At the command prompt, enter stretch

Select objects: use the CPOLYGON or cross object selection method (1,2)

Base point or displacement: specify a point (3) or press

Second point of displacement: specify a point ($) or press


5. EXTEND: This extends an object to meet another object. Objects that can be extended

include arcs, elliptical arcs, lines, open 2D, and 3Dpolylines and rays.

At command prompt, enter extend

Select boundary edges

(projmode=UCS, edge mode=no extend)


6. SCALE: This enlarges or reduces selected objects equally in X and Y directions

At the command prompt, enter scale


Base point: specify a point (1)

<Scale factor>/reference: specify a scale or enter r

7. TRACE: This creates solid lines.

From the miscellaneous tool bar choose

At the command prompt, enter trace

Trace width<current>: specify a distance, enter a value, or press enter

From point: specify point (1)

To point: specify a point (2)

To point: specify a point (3) or press to end the command

8. EXTRUDE: This creates unique solid primitives by extruding existing two-dimensional

objects extrudes also creates solids by extruding two-dimensional objects along a specified

path .we can extrude multiple objects with extrude


At the command prompt enter, extrude


Path/<height of extrusion>: specify a distance or enter p

9. MIRROR: This is used to producing mirror image of the object

At the command prompt enter, mirror


First point of the mirror line: specify a point (1)

Second point: specify a point (2)

10. OFFSET: This creates concentric circles ,parallel lines and parallel curves, offset creates a

creates a new object at a specified distance from an existing object or through a specified

point

At the command prompt enter, offset

Offset distance: specify a distance, enter t or press enter

11. ARRAY: This creates multiple copies of objects in pattern.

Each object in an array can be manipulated independently

At the command prompt enter, array

Rectangular or polar array<current>: enter an option or press enter specify a point


12. CUTTING OF OBJECTS

The drawn objects can be cut or trimmed by using following commands

1. TRIM: Trims objects at a cutting object defined by other objects. Objects that can be trimmed

include arcs ,circles, elliptical arcs, lines, open 2D and 3Dpolylines,rays and splines

At the command prompt, enter trim

Select cutting edges:

Select objects: use object selection method

<Select object to trim>/project/edge/undo: select an object, enter an option, or press enter

2. BREAK: This erases an object or splits the object in to two parts

From the modify toolbar select break flyout

At the command prompt, enter break


First point of the mirror line: specify a point (1) on an object

Enter second point: specify the second break point (2) or enter F

13. DIMENSIONING IN DRAWINGS:

The dimensions are inserted in the drawing by use of DIM command. There are various types of

dimensions used in AutoCAD.

1. Linear dimensions:

Horizontal- this allows horizontal dimensions

Vertical- this allows vertical dimensions

Aligned- this allows inclined dimensions


Rotated- this allows inclined dimensions

2. Angular dimensions:

This allows angular dimensioning of objects

3. Radial dimensions:

This allows radial dimensioning of arc or circle

4. Diametric dimensions:

This allows diametral dimensions of the circle

For dimensioning of objects, the first point and second point has to be specified. The dimension text

must be written and then the position of dimension must be specified

At the command prompt, enter dim

Dim: Enter a dimensioning mode command

14. AREA:

This allows calculation of the area and perimeter of objects or of defined areas

From the object properties toolbar, choose the inquiry flyout, then

At the command prompt, enter area

<First point>/object/add/subtract: specify a point or enter option

15. FILLET

Rounds and fillets the edges of the object

At the command prompt enter fillet

Polyline / Radius / Trim / <Select first object>: use an object selection method or enter an option


Select first object

Select second object: use an object selection method

Enter radius <current>: specify a distance or press

Chain / Radius <Select edge>: Select edges or enter c or r their intersection

16. CO-ORDINATE SYSTEM

The coordinate system can be modified in the AutoCAD. There are two types of coordinate

systems used. The WCS (World coordinate system) is a universal system in which its origin is

at the fixed position. The UCS (User coordinate system) is a system in which user can fix his

origin at any point.

1. UCS : This manages user coordinate systems

At the command prompt enter UCS

Origin / z axis/ 3 point/ object/ view/ X/Y/Z / Prev/ Restore/Save/ Del/?/< world>: enter an

option or press enter

2. WCS: This manages world coordinate system

17. EXPLODE:

This breaks a compound object into its component objects

At the command prompt enter explode

Select objects: use an object selection method.

18. UNION:

This measures the distance and angle between two points.

At the command prompt, enter union

Select object: Use an object selection method


19. DIST: This measures the distance and the angle between two points.

At the command prompt area enter dist

First point: Specify a point (1)

Second point: Specify a point (2)

Distance = calculated distance

Angle in XY plane = angle from XY plane = angle

Delta X = change in X

Delta Y = change in Y

Delta Z = change in Z.

20. REGENERATION OF DRAWING:

ACAD provides a facility of regenerating a drawing to clear the cross points or marks on the

screen.

REDRAW

REGEN

REGENALL

REGENAUTO

21. TOLERANCE

This creates geometric tolerances. Geometric tolerances define the maximum allowable variations

of form or profile, orientation, location and runout from the exact geometry in a drawing. They

specify the required accuracy for proper function and fit the objects drawn in AutoCAD


22. SKETCH

This creates a series of free hand line segments.

From the miscellaneous toolbar, choose

At the command prompt enter sketch

Follow the prompting

2.5 3D FUNCTIONS

1. BOX

This creates a three dimensional solid box.

At the command prompt enter box

Center/<corner of the box><0,0,0> :

Specify a point (1), enter c, or press enter

Corner of a box

Specifying a point or pressing defines the first corner of the box.

Cube/length /<other corner>: specify a point (2) or enter an option center

Creates the box by a specified center point

2. CONE

This creates a 3D solid cone. A cone is solid primitive with a circular or elliptical based

tapering symmetrically to a point perpendicular to its base.

At the command prompt enter cone

Elliptical /<center point> <0,0,0>: specify a point, enter e or press enter


3. CYLINDER

This creates a 3D solid cylinder. A cylinder is solid primitive with a circular or elliptical

based to a point perpendicular to its base without a taper.

At the command prompt enter cylinder

Elliptical /<center point> <0,0,0> : specify a point, enter e or press enter

4. SPHERE

This creates a 3D solid sphere. A sphere is positioned so that its central axis is parallel to the

Z-axis of the current UCS. Latitudinal lines are parallel to the XY plane.

At the command prompt enter sphere

center of the sphere <0,0,0> : specify a point , enter e or press enter

5. WEDGE

This creates a three dimensional solid with a sloped face tapering along X axis.

At the command prompt enter wedge

Center <corner of the wedge> <0,0,0> : specify a point, enter e or press enter


6. ELEV

This sets an elevation and extrusion thickness of new objects. The current elevation is the Z

value that is used whenever a 3D point is expected but only X and y values are supplied.

At the command prompt enter elev



7. SHADE

This displays a flat shaded image of the drawing in the current view port. SHADE removes

hidden lines and displays a shaded picture of the drawing.

From the render toolbar, choose

At the command prompt, enter shade

8. REGION

This creates a region object from a selection set of existing objects. Regions are

2Dimensional areas you create from closed shapes.

9. REINIT

This reinitializes the input/output ports, digitizer, display and program parameters file.

10. REPLAY

This displays a GIF, TGA or TIFF image.

From the tools menu, choose image, then view.

11. REVOLVE

This creates a solid by revolving a two – dimensional object about an axis. From the solids

toolbar, choose

At the command prompt, enter revolve

12. SHAPE

This inserts a shape. Before inserting a shape, you must load the file containing the desired

shape.


13. ROTATE 3D

This moves objects about a three dimensional axis

From the modify toolbar, choose the rotate flyout then


14. SECTION

This uses the intersection of a plane and solids to create a region.

AutoCAD creates regions on the current layer and inserts them at the location of the cross –

section. Selecting several solids creates separate regions for each solid.

15. SLICE

This slices a set of solids with a plane.

16. SHELL

This accesses operating system commands.

17. REVOLVE

This creates a solid by revolving a two dimensional object about an axis.

18. RENDER

This creates a realistically shaded image of a three dimensional wireframe or solid model.

RENDER produces an image using information from a scene, the current selection set, or the

current view.

2.6 Starting the drawing

The figures we do in engineering are fitted into a template. In ACAD we manually draw a template

known as Drawing sheet in two different formats.

The size of the drawing sheet is ISO A4 210 X 297.

The format is as given in the following figures


3. 2D DRAWINGS

FIGURE 1

Aim: to draw the following figure using ACAD

PROCEDURE

Set the limits of the drawing screen

STEP 1: Draw axis lines in the respective format with their intersection point at (0,0)

Go to PROPERTIES tool bar

Load line type as ISO LONG DASH SHORT DASH in the line type area.

Select line type ISO LONG DASH SHORT DASH in the line type area.


STEP 2 a: Draw circles of given dimensions using circle command with their centre as the intersection

of the axis lines.

3 circles of diameters 94, 74 and 54 are to be drawn

The circle with 74 diameter is of ISO LONG DASH SHORT DASH format

STEP 2 b: Using POLAR ARRAY draw the 6 holes on the circle of diameter 74 each of 12 dia as

shown in the figure below

STEP 3: Draw two construction lines at an angle of 30o to the vertical axis line

STEP 4: With A as center an radius 100 draw an arc between the above lines

STEP 5: Offset the arc on the either side by the distances as mentioned in the figure.

STEP 6: Complete the figure by using fillet command.

STEP 7: Give dimensions to the completed figure.

Command: _qsave

PRECAUTIONS:

Put ORTHO ON where ever necessary.

Use the required modify tool bar commands like TRIM, ERASE, COPY, MIRROR ETC.,


FIGURE 2


PROCEDURE

Set the limits of the drawing screen

STEP 1: Draw axis lines in the respective format with their intersection point at (0,0)

STEP 2: Draw circles of given dimensions using circle command with their centre as the intersection of

the axis lines.

STEP 3: Using POLAR ARRAY draw the 6 key holes on the circle of diameter 58 of given dimensions

STEP 4: For the outer cover use CIRCLE command and the in command prompt area type TAN TAN

RADIUS. This gives the idea of drawing the outer cover

STEP 7: Give dimensions to the completed figure.

Command: _qsave


PRACTICE FIGURE 3

PRACTICE FIGURE 4


PRACTICE FIGURE 5

PRACTICE FIGURE 6


4. ISOMETRIC DRAWINGS

For all isometric figures right click GRID in drafting tool bar <setting> change grid snap to

ISOMETRIC SNAP. And check ORTHO ON

F5 – TOGGLE KEY BETWEEN ISOPLANE TOP, ISOPLANE LEFT AND ISOPLANE RIGHT

FIGURE 1


COMMANDS USED

Line, Dimensions, Drafting commands

PROCEDURE

<Ortho on> <Isoplane Top> <Osnap on>

Command: _line Specify first point:

Specify next point or [Undo]: 104

Specify next point or [Undo]:

Command: _qsave

Command: _dimaligned

Specify first extension line origin or <select object>:

Specify second extension line origin:

Command: _dimlinear



Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]:

Dimension text = 48.0000

Command: _dimedit

Enter type of dimension editing [Home/New/Rotate/Oblique] <Home>: _o

Select objects: 1 found

Enter obliquing angle (press ENTER for none): 30

Command: _qsave


FIGURE 2


COMMANDS USED

Line, Drafting commands, Dimension aligned, Dimension linear, Dimension oblique, Layers

Command: _line

Specify first point: <Isoplane Left>

Specify next point or [Undo]: 12

Specify next point or [Undo]: <Isoplane Top>

25

Command: _qsave

Command: _dimlinear

Specify first extension line origin or <select

object>:


Specify dimension line location or

[Mtext/Text/Angle/Horizontal/Vertical/Rotated]:


Command: _dimaligned



Specify dimension line location or [Mtext/Text/Angle]:


Command: _dimedit

Enter type of dimension editing [Home/New/Rotate/Oblique] <Home>: _o

Select objects: 1 found

Enter obliquing angle (press ENTER for none): 30 or -30

Command: _qsave


5. 3- D DRAWINGS

The commands used while draing 3D solids are briefly discussed in the beginning.

The major commands used are:

Pedit – To join the individual poly line segments

Explode - To break the joined part into individual entities

Extrude – To add thickness to the object and create a solid

Union – To unite two solids and form an union

Intersect – To form an intersection of two solids

Shade – This displays a flat – shaded image of the drawing in the current viewport.

SHADE removes hidden lines and displays a shaded picture of the drawing

Rotate 3D – This moves objects about a three dimensional space

Revolve – This creates a solid by revolving a two – dimensional object about an axis

Region – This creates a region object from a selection set of existing objects. Regions are

two dimensional areas.

View ports – Splits the screen into a number of ports. Enables us to have a multi viewing

of the object at the same time.

VIEW pull down menu View ports

3D ORBIT - Allows us to rotate the object on a 3 dimensional axis.

VIEW pull down menu 3D orbit

3D VIEWS - Allows us to visualize the views of object

VIEW pull down menu 3D view


PRACTICE FIGURE – 1


PROCEDURE:

STEP 1: Set your screen to SW ISOMETRIC VIEW.

Go to VIEW pull down menu.

Select 3D VIEWS and from the sub menu select SW ISOMETRIC VIEW.

STEP 2: Using RECTANGLE command draw the bottom rectangle of dimensions 80 X 60 and

EXTRUDE it to a height of 40. We get the outside solid

To put the holes required on the front and the side of the solid,

STEP 3: Draw the inner rectangles and extrude them as per give dimensions

STEP 4: Subtract the inner solids from the outer one

We can use different colors to distinguish between the solids, so that it is easier to subtract.

STEP 5: Shading can be done to the wire frame model using commands in the SHADE tool bar.

The front, top and the side views of the figure can be obtained from the

View pull down menu 3D views Front view etc.

The model can be made to orbit using

View pull down menu 3D ORBIT


INTRODUCTION

TO CREO 2.0

1

OVERVIEW The main objective of this lesson is to introduce you to the general procedures for creating sketched

features. We will go at quite a slow pace and the part will be quite simple (see Figure 1 on the next

page), but the central ideas need to be elaborated and explored so that they are very clearly

understood. Some of the material presented here is a repeat of the previous lesson - take this as an

indication that it is important! Here’s what we are going to cover:

1. Creating a Solid Part

2. Introduction to Sketcher

< Sketcher menus

< Intent Manager and Sketcher constraints

< Sketcher Diagnostics

3. Creating a Sketch

4. Creating an Extruded Protrusion

< Using the Dashboard

5. Creating an Extruded Cut

6. Saving the part

7. Using Part Templates

Start Creo Parametric as usual. If it is already up, close all windows (except the base window) and

erase all objects in session using File ' Manage Session ' Erase Current and/or File ' Manage

Session ' Erase Not Displayed. Close the Navigator and Browser windows.

CREATING A SIMPLE PART In this lesson, we will create a simple block with a U-shaped central slot. By the end of the lesson

your part should look like Figure 1 below. This doesn't seem like such a difficult part, but we are

going to cover a few very important and fundamental concepts in some depth. Try not to go through

this too fast, since the material is crucial to your understanding of how Creo Parametric works. We

will be adding some additional features to this part in the next lesson.

We are going to turn off some of the default actions of Creo Parametric. This will require us to do

some things manually instead of letting them happen automatically. This should give you a better

understanding of what the many default actions are. Furthermore, eventually you will come across

situations where you don’t want the defaults and you’ll need to know your way around these options.

2

Figure 1 Part at the end of this lesson Figure 2 Creating a new part

Creating and Naming the Part

Click the {Home}: New short-cut button, or select File ' New. A window will open (Figure 2)

showing a list of different types and sub-types of objects to create (parts, assemblies, drawings, and

so on). In this lesson we are going to make a single solid object called a part. Keep the default radio

button settings

Part | Solid

IMPORTANT: Turn off (remove the check) the Use Default Template option at the bottom. We

will discuss templates at the end of this lesson.

Many parts, assemblies, drawings, etc. can be loaded simultaneously

in the current session. All objects are identified by unique names1. A

default name for the new part is presented at the bottom of the

window, something like [prt0001]. It is almost always better to have

a more descriptive name. So, double click (left mouse) on this text to

highlight it and then type in

[block]

(without the square brackets) as your part name. The Common

Name of the part is an option for specifying an even more

descriptive name. For example, you might have a number of part

files named using a part or catalog number such as “TG123_A29".

This is not very descriptive, so you could enter a common name

such as “small flat rubber washer”. We will not use common names

in this tutorial, so leave this blank and just press Enter or select OK.

3

The New File Options dialog window opens. Since we elected (in the previous window) to not use the

default template for this part, Creo Parametric is presenting a list of alternative templates defined for

your system. As mentioned previously, we are going to avoid using defaults this time around. So, for

now, as shown in Figure 3 at the right, select

Empty | OK (or middle click).

At this time, BLOCK should appear in the title area at the top of the graphics window and the part

modeling ribbon has appeared.

Create Datum Planes

We will now create the first features of the part: three reference planes to locate it in space. It is not

absolutely necessary to have datum planes, but it is a very good practice, particularly if you are going

to make a complex part or assembly. Datum planes are created using the Plane command in the

{Model}:Datum group. Note that this button looks quite similar to the buttons that control the display

of datums and tags in the {View} tab of the ribbon. What’s the difference?

Select the Plane button now. Since we currently have no features in the model, Creo rightly assumes

that we want to create the three standard datum planes.

In the {View}:Show group, make sure that display of all datums and tags are turned on. The datum

planes represent three orthogonal planes to be used as references for features that will be created later.

You can think of these planes as XY, YZ, XZ planes, although you generally aren’t concerned with

the X,Y,Z form or notation. Your screen should have the datum planes visible, as shown in Figure 4.

They will resemble something like a star due to the default 3D viewing direction. Note that each plane

has an attached tag that gives its name: DTM1, DTM2, and DTM3. This view may be somewhat

hard to visualize, so Figure 5 shows how the datum planes would look if they were solid plates in the

same orientation. An important point to note is, while the plates in Figure 5 are finite in size, the

datum planes actually extend off to infinity. Finally, before we move on to the next topic, notice that

the last feature created (in this case DTM3), is highlighted in green. This is a normal occurrence and

means that the last feature created is always preselected for you as the “object” part of the

object/action command sequence.

Figure 4 Default datum planes Figure 5 Datum planes as solid plates

4

Part Modeling Feature Overview There are three command groups in the {Model} tab of the modeling ribbon that will create solid

features. These are shown in Figure 6. Two of these groups contain commands for creating features,

organized into the following categories:

Shaped Features (formerly known as “sketched features) - (extrusions, revolves, sweeps, blends, ..)

These features require the definition of a two-dimensional cross section which is then manipulated

into the third dimension. All of these features can either add or remove material from the solid.

Although they usually use existing geometry for references, they do not specifically require this.

These features will involve the use of an important tool called Sketcher.

Engineering (formerly known as “placed features”) - (holes, rounds, shells, ...) These are features

that are created directly on existing solid geometry. They generally always either add (rib) or remove

(hole) material from the solid. Some (round, chamfer, draft) can do either. Examples are placing a

hole on an existing surface, or creating a round on an existing edge of a part.

The third group of buttons, Editing, is used for editing and modifying existing features. We will deal

with some of these commands (Mirror and Pattern) later in the Tutorial.

Figure 6 Ribbon groups for creating and editing solid features

In this lesson we will be using the Extrude command to create two types of shaped features (a

protrusion and a cut). In the next lesson, we will use the Hole, Round, and Chamfer commands to

create three engineering features. Before we continue, though, we must find out about an important

tool - Sketcher.

INTRODUCING SKETCHER Sketcher is the most important tool for creating features in Creo Parametric. It is therefore critical that

you have a good understanding of how it works. We will take a few minutes here to describe its basic

operation and will explore the Sketcher tools continually through the next few lessons. It will take you

a bit of practice and experience to fully appreciate all that it can do.

Basically, Sketcher is a tool for creating two-dimensional figures. These can be either stand-alone

features (Sketched Curves) or as embedded elements that define the cross sectional shape of some

solid features. The aspects of these figures that must be defined are location, shape, and size, roughly

in that order. The sketching plane where we will create the 2D sketch is defined or selected first.

Then, within Sketcher the location is further specified by selecting references to existing geometry.

You will find the usual drawing tools for lines, arcs, circles, and so on, to create the shape. Finally,

5

you can specify dimensions and/or alignments to control the size of the sketch and its relation to

existing geometry.

Sketcher is really quite smart, that is, it will anticipate what you are going to do (usually correctly!)

and do many things automatically. Occasionally, it does make a mistake in guessing what you want.

So, learning how to use Sketcher effectively involves understanding exactly what it is doing for you

(and why) and discovering ways that you can easily over-ride this when necessary.

The brain of Sketcher is called the Intent Manager. We will be discussing the notion of design intent

many times in this tutorial. In Sketcher, design intent is manifest not only in the shape of the sketch

but also in how constraints and dimensions are applied to the sketch so that it is both complete and

conveys the important design goals for the feature. Completeness of a sketch implies that it contains

just enough geometric specification so that it is uniquely determined. Too little information would

mean that the sketch is under- specified; too much means that it is over-specified. One function of

Intent Manager is to make sure that the sketch always contains just the right amount of information.

Moreover, it tries to do this in ways that, most of the time, make sense. Much of the frustration

involved in using Sketcher arises from not understanding (or even sometimes not realizing) the

nature of the choices it is making for you2 or knowing how easy it is to override these actions. When

you are using Sketcher, Intent Manager must be treated like a partner - the more you understand how

it works, the better the two of you will be able to function.

The term sketch comes from the fact that you do not have to be particularly exact when you are

“drawing” the shape, as shown in Figures 7 and 8. Sketcher (or rather Intent Manager) will interpret

what you are drawing within a built-in set of rules. Thus, if you sketch a line that is approximately

vertical, Sketcher assumes that you want it vertical. If you sketch two circles or arcs that have

approximately the same radius, Sketcher assumes that’s what you want. In cases like this, you will

see the sketched entity “snap” to a particular orientation or size as Intent Manager fires one of the

internal rules (this occurs on-the-fly while you are sketching).

Figure 7 Geometry input by user

(Intent Manager rules off). Note

misaligned vertices, non-parallel edges,

non-tangent curves.

Figure 8 Geometry after processing by

Intent Manager. Note aligned vertices,

parallel edges, tangent curves.

6

When Sketcher fires one of its internal rules, you will be alerted by a symbol on the sketch that

indicates the nature of the assumed condition. If you accept the condition, it becomes a constraint

on the sketch. These constraints are summarized in Table 2-1. You should become familiar with

these rules or constraints, and learn how to use them to your advantage. If you do not want a rule

invoked, you must either

(a) use explicit dimensions or alignments, or

(b) exaggerate the geometry so that the rule will fail, or

(c) tell Sketcher to disable a specific instance of the constraint (Hint: RMB), or

(d) set up Sketcher to explicitly ignore constraints of a given type.

You will most often use option (a) by specifying your desired alignments and dimensions and

letting Sketcher worry about whatever else it needs to solve the sketch. When geometry is driven by

an explicit dimension, fewer internal rules will fire. Option (b) is slightly less common. An

example is if a line in a sketch must be 2E away from vertical, you would draw it some much larger

angle (like 15E or so) and put an explicit dimension on the angle. This prevents the “vertical” rule

from firing. Once the sketch has been completed with the exaggerated angle, you can modify the

dimension value to the desired 2E. The third option is used on-the-fly while you are sketching to

disable a constraint that Intent Manager indicates it wants to place. Finally, there are settings for

Sketcher that explicitly turn off the rule checking (for all rules or selected ones only) during

sketching. This is very rarely used.

An example of a sketch with geometric constraints is

shown in Figure 9. Note how few dimensions are

required to define this sketch.

See if you can pick out the following constraints:

< Vertical lines

< Horizontal lines

< Perpendicular lines

< Tangency

< Three sets of equal length lines

< Equal radius

< Vertical alignment

How do you suppose Sketcher is able to determine the

radius of the rounded corners (fillets) at the top and

bottom on the left edge? (Hint: this involves the

solution of a system of equations.)

Figure 9 A sketch showing implicit

constraints

Sketcher has some very useful tools that make it considerably easier to diagnose errors in sketches

(such as duplicated edges) or improper sketches (such as open curves for features that require closed

curves). We will investigate these tools by intentionally introducing some errors into our sketches.

7

Table 2-1 Implicit Constraints in Sketcher

Rule

Symbol

Description

Equal radius and

diameter

R

If you sketch two or more arcs or circles

with approximately the same radius, the

system may assume that the radii are equal

Symmetry

Two vertices may be assumed to be

symmetric about a centerline

Horizontal or vertical

lines

H or V

Lines that are approximately horizontal or

vertical may be considered to be exactly so.

Parallel or

perpendicular lines 2 or z

Lines that are sketched approximately

parallel or perpendicular may be considered

to be exactly so.

Tangency

T

Entities sketched approximately tangent to

each other may be assumed to be tangent

Equal segment

lengths

L

Lines of approximately the same length

may be assumed to have the same length

Point entities lying

on other entities or

collinear with other

entities

Point entities that lie near lines, arcs, or

circles may be considered to be exactly on

them. Points that are near the extension of a

line may be assumed to lie on it.

Equal coordinates

(( ((

Endpoints and centers of the arcs may be

assumed to have the same X- or the same

Y-coordinates

Midpoint of line

M

If the midpoint of a line is close to a sketch

reference, it will be placed on the reference.

Two Ways to use Sketcher to Create Shaped Features In this lesson, we will use two methods to create a couple of shaped features. The creation of the

sketch represents the majority of the work required in creating these features. The two methods will

differ by where in the feature creation sequence you will invoke Sketcher. The two methods are

shown schematically in Table 2 - 2.

In the first method, we invoke Sketcher first to create the cross sectional shape of the extrusion.

This shape is defined in a sketched curve which becomes a stand-alone feature in the model. We

then launch the extrude command, specifying the curve to define the cross section of the feature. A

dependent copy of the sketch is brought into the extrude feature. The original sketch feature is

8

automatically set to Hide. In the second method, we do not create a separate curve but rather invoke

Sketcher from inside the extrusion creation sequence. In this case, the sketch exists only inside the

extrude definition and is not usable by other features. In the Table below, notice the difference in

the appearance of the model tree following completion of the extruded feature

Table 2-2 Steps to create a sketched feature

Method 1

Method 2

Step 1

Create shape using Sketcher (sketch becomes stand alone feature)

Launch Extrude tool

Step 2

Launch Extrude tool

Create shape using Sketcher (sketch exists only inside the extrude feature)

Model Tree

after

completion

of

Extrude

In terms of design intent, the first method would be used if the sketched curve was going to be used

for additional features, for example an extrude and a subsequent revolve. The second method

(creating the sketch within the feature) is the traditional mode of operation, and would be the

method of choice if the sketched shape was to be used only in the single feature.

Both features we will make here are extrusions: one will be a protrusion (which adds material) and

the other is a cut (which removes material). Either of the two methods shown here can be used to

create either protrusions or cuts; for either method, whether you add or remove material is

determined by a single mouse click!

CREATING A SKETCHED CURVE The last feature we created in the Block model was the datum DTM3. If that is currently selected

(highlighted in green), unselect it by clicking somewhere else in the graphics window. The

behavior of Sketcher is different if we enter it with a plane already selected.

Now in the {Model}:Datum group select the Sketch tool .

9

Setting Sketch Orientation The Sketch dialog window opens (Figure 10) where

we must specify two references. The first is the

Sketch Plane. Select the border of DTM3 (or click it

in the model tree). It is now highlighted in the

graphics window in cyan. This is the plane on which

we will draw the sketch. Sketcher will automatically

pick the second reference, probably DTM1, but this

will depend on the orientation of the datum planes on

your screen. It will also automatically assign an

Orientation - see Figure 10. This also depends on

the current orientation of the datums3.

A magenta arrow shows the direction of view onto

the sketching plane. Spin the orientation with the

middle mouse button to see the arrow. The arrow

Figure 10 Defining the sketch

plane and sketch orientation

reference

attached to the edge of DTM3 should be pointing back into the screen. The direction of view can be

reversed by clicking directly on the magenta arrow or with the Flip button in the dialog window.

Leave it pointing towards the back. In the dialog window, DTM1 is identified as the Sketch

Orientation Reference, with the Orientation set to Right. What is all this about?

The relation between the sketch plane and the sketch orientation reference generally causes a

lot of confusion for new users, so pay attention!

The meaning of the sketch plane is pretty obvious - it is the plane on which we will draw the sketch -

in this case DTM3. A 2D view is always perpendicular to the sketch plane4. That is not enough by

itself to define our view of the sketch since we can be looking at that plane from an infinite number

of directions (imagine the sketch plane rotating around an axis perpendicular to the screen). The

Orientation option pull-down list in the dialog window (Top, Bottom, Left, Right) refers to

directions relative to the computer screen, as in “TOP edge of the screen” or “BOTTOM edge of the

screen” and so on. We must combine this direction with a chosen reference plane (which must be

perpendicular to the sketch plane) so that we get the desired orientation of view onto the sketching

plane.

In the present case, when we get into Sketcher we will be looking directly at the brown (positive)

side of DTM3. So that the sketch is the right way up, we can choose either DTM2 to face the Top of

the screen, or (as was chosen automatically for us) DTM1 can face the Right of the screen.

3 If the contents of your dialog window do not look like Figure 10, cancel out of the dialog window,

press Ctrl-D to get to the default orientation, and launch the Sketch command again. 4Well, almost always. It is possible to sketch in 3D, in which case you can manipulate your view so

that you are not looking perpendicularly at the sketch plane, but all 2D entities still lie only in the

designated sketch plane.

10

Note that both DTM1 and DTM2 are both perpendicular to the sketch plane, as required. The

direction a plane or surface “faces” is determined by its normal vector. The normal vector for a

datum plane is perpendicular to the brown side. For a solid surface, the orientation is determined by

the outward normal.

Read the last couple of paragraphs again, since new users are quite liable to end up

drawing their sketches upside-down!

Figure 11 The importance of the sketching reference plane! The shaded images are both in

the default orientation. The same sketching plane and sketch was used for both features - the

difference in orientation of the solid is because of the choice of the sketching reference

plane.

To illustrate the crucial importance of the reference plane, consider the images shown in Figure 11.

These show two cases where the same sketching plane DTM3 was used, the same sketched shape

was drawn, the same reference orientation TOP was chosen, but where different datums were chosen

as the sketching reference. On the left, the TOP reference was DTM2. On the right, the TOP

reference was DTM1. The identical sketch, shown in the center, was used for both cases (rounded

11

end of sketch towards the top of the screen). However, notice the difference in the orientation of the

part obtained in the final shaded images. Both of these models are displayed in the default orientation

(check the datum planes). Clearly, choosing the sketching reference is important, particularly for the

base feature.

Let’s continue on with creating the curve. Make sure the

Sketch dialog window is completed as in Figure 10. Select

the Sketch button (or middle click).

Several changes occur on the screen. First, a new ribbon tab

has appeared containing the sketching tools. Second, a

couple of new buttons have shown up on the Graphics

toolbar. Take a moment to check these out with the popup

tool tips. Finally, a couple of dashed cyan lines have

appeared in the graphics area. What are these about?

To verify the meaning of the dashed lines, select

{Setup}: References

Figure 12 Choosing references

in Sketcher

(Or select References in the RMB pop-up). This opens the References dialog window, Figure 12. In

this window we can select any existing geometry to help Sketcher locate the new sketch relative to

the part. In the present case, there isn’t much to choose from, and two references have already been

chosen for us - DTM1 and DTM2. These references are responsible for the two dashed lines in the

graphics window. The number of references you choose is not limited (there may be several listed

here) and a reference can be any existing geometric entity (plane, straight or curved edge, point,

axis, projected edge, and more). You are also free to delete the ones chosen for you and/or add new

ones.

However, notice the Reference Status at the bottom of this dialog. Fully Placed means enough

references have been specified to allow Sketcher to locate your sketch in the model. If there are not

enough references, the status will be Unsolved Sketch. For now, do not proceed beyond this

window unless you have a Fully Placed status indicated. Once you have that, select Close in the

References window.

So that we are looking directly at the sketch plane,

in the Graphics toolbar select the Sketch View

button . The graphics window is shown in

Figure 13. Note that you are looking edge-on to the

datums DTM1 and DTM2. The datum DTM1

(actually, its brown side) is facing the right edge of

the screen, as specified in the dialog back in Figure

10. Note that we could have obtained the same

orientation by selecting DTM2 to face the top of the

screen.

Figure 13 The drawing window

12

In the Graphics toolbar there is a new set of Sketcher Display

Filters (Figure 14). Leave these options in their default value

(Dimensions, Constraints, Vertices, all turned on). It is seldom (if

ever) that you will need to turn on the grid in Sketcher.

The major change on the screen is the appearance of the Sketch

ribbon. Let’s take some time to explore it.

The Sketch Ribbon

Figure 14 Filters for sketch

entities

The Sketch ribbon is shown in Figures 15 and 16. You should explore the groups for a while to

familiarize yourself with the commands available. Some things you should note about the groups and

commands are the following (starting from the left):

Setup - allows you to reset the sketch plane and references, sketching options, and to

reorient your view (note this button is also on the Graphics toolbar)

Get Data - lets you read in a previously created sketch

Operations - these include the normal selection, cut, copy, past commands

Datum - these buttons will create entities in the sketch that will appear and operate the same as

datums in the model, but they are stored within the sketch. These were previously called

geometry datums. They will create a datum element that is visible outside the sketch (and could

be used as reference by another feature). For example, a Geometry Point creates a datum axis

that will be perpendicular to the sketch plane.

Figure 15 Sketcher ribbon (part 1)

Sketching - these will be your most-used commands. The Construction Mode button will

toggle between real geometry and construction geometry. Real geometry will produce the

feature, while construction geometry is only used to help define the sketch. An example would

be using a construction circle to create an inscribed hexagon. You can also switch entities from

construction to real (or vice versa) after they have been created. The rest of the sketching

buttons do the actual geometry creation. Note that most buttons have flyouts to addition

variations of the command. For example, check out the rectangle

13

button. We will spend a lot of time exploring some of these options. Finally, the Palette

command lets you choose from several different families of 2D shapes that have already been

created for you. We will use this command a bit later in these lessons.

Figure 16 Sketcher ribbon (part 2)

Editing - contains commands for modifying geometry by changing dimensions using a special

dialog window, trimming (and extending) entities, mirroring of entities, dynamic trim, and

translating, rotating, and scaling a group of entities simultaneously.

Constrain - these are the constraints that Intent Manager will invoke automatically, but you

can also explicitly assign these constraints to a sketch. See Table 2-3.

Dimension - does pretty much what you would expect - allow you to create dimensions on the

sketch. There are several varieties, including reference, ordinate, and perimeter.

Inspect - these contain tools to help you diagnose problems with your sketch. For our first

sketch, turn on the Shade Closed Loops and Highlight Open Ends buttons.

Close - lets you accept the sketch or quit without keeping or using the sketch. Note that the

latter is irreversible (you cannot Undo it).

It is going to take a while to get comfortable with all the commands in the ribbon.

Fortunately, there is a small subset that will be used repeatedly.

Helpful Hint

In the following, keep in mind that many functions in Sketcher are available in context

sensitive pop-up menus attached to the RMB. For many sketches, you need never actually

pick a ribbon button since almost everything is available in the graphics window using

RMB commands only. Try it!

14

Table 2-3 Explicit Constraints in Sketcher

Constraint

Vertical

Tangent

Symmetric

Horizontal

Mid-point

Equal

Perpendicular

Coincident

Parallel

CREATING THE SKETCH

Select the Line Chain tool using one of the following three

methods:

• using the Line Chain button in the Sketching group,

OR (probably the easiest!)

• hold down the RMB and select Line Chain from the

pop-up menu (Figure 17).

You will now see a small X with a dot at its center which will chase

the cursor around the screen. Notice that the X will snap to the dashed

references when the cursor is brought nearby, but not to the displayed

edges of DTM3. While you are creating the sketch, watch for green

symbols (V, H, L) that indicate Intent Manager is firing an internal

rule to set up a constraint (Vertical, Horizontal, Equal Length). These

Figure 17 RMB pop-up

menu in Sketcher

symbols will come and go while you are sketching. The trick with Sketcher is to get Intent Manager

to fire the rule you want, then click the left mouse button to accept the position of the vertex. Click

the corners in the order shown in Figure 18. After each click, you will see a straight line rubber-band

from the previous position to the cursor position:

15

1. left-click at the origin

(intersection of DTM1

and DTM2)

2. left-click above the

origin on DTM1 (watch

for V)

3. left-click horizontally to

the right (watch for H

and L - we do not want

L)

4. left-click straight down

on DTM2 (watch for V)

5. left-click back at the

origin (watch for H)

6. middle-click anywhere

on the screen to end line

creation

Figure 18 Drawing the Sketch

When you are finished this sequence, you are still in Line creation mode (notice the X on screen and

the Line Chain ribbon button). If you middle click again, you will leave that and return to Select

mode - the same as if you picked on the Select button in the ribbon, but much faster.

Helpful Hint

From wherever you are in the Sketcher menu structure, a single middle mouse click will

often abort the current command and return you to the toolbar with the Select command

already chosen. Sometimes, yosu may have to click the middle button twice.

The sketched entities are shown in orange. Since we have created a closed curve, the interior of the

sketch is shaded (because of the Shade Closed Loops button in the ribbon). Many features require

sketches to contain only closed loops, so this is an easy way to verify that condition. At some point

or other, you will create a sketch that you think is closed, but it will not shade. This usually means

you have extraneous entities in the sketch (usually duplicated lines or edges) or the corners do not

exactly close. We will see an example of duplicate lines in a few minutes.

Note that we didn't need to specify any drawing coordinates for the rectangle, nor, for that matter,

are any coordinate values displayed anywhere on the screen. This is a significant departure from

standard CAD programs. We also didn’t need the grid (this is available if you want it, along with a

snap function).

You can also sketch beyond the displayed edges of the datum planes - these actually extend off to

infinity. The displayed extent of datum planes will (eventually) adjust to the currently displayed

object(s).

16

Helpful Hints

If you make a mistake in drawing your shape, here are some ways to delete entities:

1. Pick the Select tool in the right toolbar and left click on any entity you want to delete.

Then either press the Delete key on the keyboard, or hold down the RMB and choose

Delete.

2. If there are several entities to delete, hold the CTRL key down while you left click

on each entity. Then pick Delete as before.

3. You can left-click and drag to form a rectangle around a set of entities. Anything

completely inside the rectangle is selected. Use Delete as before.

4. Notice the Undo and Redo buttons on the top toolbar

We will cover more advanced Sketcher commands for deleting and trimming lines a bit

later.

After you have finished the sequence above, Sketcher will put

two dimensions on the sketch - for the height and width of the

rectangle. These will be in light blue, similar to those shown in

Figure 19. For the first feature in a part, the numerical values

of these dimensions are picked more-or-less at random

(although they are in correct proportion to each other)5. For

later features in the part, Sketcher will know the sketch size

more accurately because it will have some existing geometry to

set the scale.

WEAK VS STRONG DIMENSIONS

A dimension created by Sketcher (or actually Intent

Manager) is called “weak” and is shown in light blue.

Figure 19 initial sketches

with weak dimensions

Strong dimensions, on the other hand, are those that you create. You can make a strong dimension in

any of three ways:

L modify the numeric value of a weak dimension

or L create a dimension from scratch by identifying entities in the sketch and placing a new dimension on the sketch

or L select a weak dimension and promote it to strong using the RMB pop-up menu

Strong dimensions will be shown in dark blue.

The special significance of weak and strong dimensions is as follows. When Intent Manager is

“solving” a sketch, it considers the sketch references, any implicit rules that have fired (like H, V,

and so on)

5 The default datum display with no other features present is actually ±250 units from

where they cross.

17

If there is not enough information to define the drawing (it is underconstrained), Sketcher will create

the necessary and sufficient missing dimensions. These are the weak dimensions. If Sketcher finds

the drawing is overconstrained (too many dimensions or constraints) it will first try to solve the

sketch by deleting one or more of the weak dimensions (the ones it made itself earlier). It will do this

without asking you. This is one way for you to override Intent Manager - if you don’t like the

dimensioning scheme chosen by Sketcher, just create your own (automatically strong) dimensions.

Sketcher will remove whichever of the weak dimensions are no longer needed to define the sketch.

Sketcher assumes that any strong dimensions you have created shouldn’t be messed with! However,

if Sketcher still finds the drawing overconstrained, it will tell you what the redundant information is

(which may be dimensions or constraints), and you can choose what you want deleted. Thus,

although weak dimensions can be deleted without asking you, Sketcher will never delete a strong

dimension without your explicit confirmation.

We want to modify the two weak dimensions on the rectangle in a couple of ways. First, we can

make a cosmetic improvement by selecting the dimension text (the number) and performing a drag-

and-drop to move it to a better location. Note in passing that preselection highlighting also works

with dimensions and constraints. Do that now, so that the dimensions are located as in Figure 20

(“off the sketch”).

Figure 20 Modified sketch

Figure 21 Completed sketch

Next, we can change the numeric values of the dimensions (it is explained later why doing this now

may not be a good idea!). Double-click on the horizontal dimension. In the text entry box, enter the

value 20. When you hit Enter, the sketch geometry will be updated with this new dimension. The

dimension is now strong. Change the vertical dimension to 30. It will also now be strong. (Click

anywhere on the graphics window to remove the green highlight and update the shading.) See

Figure 20.

Notice that the indicated extent of the datum plane DTM3 adjusts to the sketch. You may want to

Refit the sketch in the graphics window (or use zoom).

18

Now we’ll add a couple of rounded corners, technically known as fillets, on the top corners of the

sketch to help us “see” the orientation of the feature in 3D. Select the Fillet command from the

RMB pop-up menu (Figure 17) and pick on the top and right lines in the sketch close to but not at

the corner. A circular fillet is created to the pick point closest to the corner. Two tangent constraints

(T) are added, along with a weak dimension for the fillet radius. Do the same on the top and left

lines. Middle click to return to Select mode.

IMPORTANT: Because our fillet command has removed two vertices on the top of the sketch,

Intent Manager has removed our two strong dimensions (which used those vertices) and replaced

them with weak ones (see the message window - you may have to scroll back a couple of lines). So

really we wasted a couple of steps by previously modifying the values of those dimensions (and

making them strong in the process). You can make them strong again by selecting them, clicking

the RMB, and selecting Strong in the pop-up menu. Modify the cosmetics and values of the fillet

radius dimensions as shown in Figure 21.

Helpful Hint

When you are creating a Sketch, the most efficient order of operations is the

following:

1. Make sure you have the references you want.

2. Create the geometry you want.

3. Make sure the constraints you want have appeared.

4. Add the dimensions that you want to control the sketch. Intent Manager will

remove any weak ones no longer needed.

5. Modify the dimension cosmetics to take the dimensions “off the sketch”.

6. Change the dimension values to the ones you want.

If you do not do things in this order, you will likely have to backtrack (as we did

above by respecifying the strong dimensions for the block).

Sketcher Diagnostic Functions

At this point, we have a completed and valid sketch. Select the Feature Requirements button

in the Sketch tools menu at the top. The window that opens indicates that the sketch is okay (all

requirements check out). Let’s introduce a common error into the sketch to see what happens. Close

the Feature Requirements window.

We will create a duplicate line on the sketch using Line Chain. Start at the bottom left corner and

end the line part way up the vertical edge towards the top, overlapping the existing line. When you

finish the line and return to Select mode (remember to middle click twice), three things will happen.

19

First, the sketch is no longer shaded, indicating that it is no longer a simple closed loop. Second, a

big red dot appears where the overlapping line ends. This indicates an open (that is, unconnected)

end of the sketch (if the Highlight Open Ends button in the Inspect group in the ribbon is on).

Third, a weak dimension will appear for the new line. Although the geometry of the sketch appears

visually correct, if we tried to use it to create a solid feature it would fail6. Now pick the

Overlapping Geometry button in the Inspect group. All lines touching the offending vertical

line will highlight in red (easier to see with the datum plane display turned off). At this point, you

would have to do some detective work to figure out where the problem was. Select the short vertical

line (note that preselection works here) and delete it. The red dot disappears and the sketch is again

shaded.

You should experiment with the Sketch Diagnostic tools

periodically as we proceed through the tutorial.

This completes the creation of our first sketch. Select the

OK in the ribbon, or in the RMB popup menu. This returns

us to the regular graphics window with our new sketched

curve shown in green (last feature created). You can spin

the model around with the middle mouse button to see this

curve from different view points. When you are finished

with this, return the model to approximately the default

orientation - Figure 22. If you click anywhere else on the

graphics window, the curve turns its default color of light

blue.

CREATING A SOLID PROTRUSION Most of the work to create this feature has been done

already - creating the sketched curve that defines its shape.

This curve should be highlighted in green. If you have

been playing around with the model and the sketch is blue,

just left click on it to select it again, or select it in the model

tree.

With the sketched curve highlighted, pick the Extrude

button in the Shapes group of the ribbon.

What you will see now is an orange shaded image of the

protrusion, Figure 23. On this shape, you will see a

magenta arrow that indicates the extrusion direction, which

by default comes off the positive side of the sketch.

Figure 22 Sketched curve

Figure 23 The protrusion

preview

20

There is also a dashed line ending in a white square. This is a drag handle. Click on this with the

mouse and you can drag it to change the length of the extrusion. This length is also shown in a

dimension symbol. You can even drag this extrusion out the back of the sketch to extrude in the

opposite direction. This direct manipulation of the feature on the screen is called, in Creo Parametric

vernacular, Direct Modeling. Bring the protrusion out the front and double click on the numeric

dimension, and enter the value 30.

Check out what happens if you hold down the RMB with nothing selected. What is in the pop-up

menu? What happens if you select the white drag handle? It should turn black. What is in the RMB

menu now?

At the top of the graphics window is a new collection of tools. These comprise the Dashboard.

Many features are constructed with tools arranged using this style of interface element. It is worth

spending some time exploring this one in detail, since you will probably be using it the most.

Helpful Hint

You may accidentally leave the dashboard with an inadvertent click of the middle

mouse button. Remember that this is a short cut for Accept. If that happens, with the

protrusion highlighted, hold down the right mouse button and select Edit Definition.

This will bring you back to the dashboard. The Undo command, if executed

immediately, will delete the feature.

THE EXTRUDE DASHBOARD The dashboard collects all of the commands and

options for feature creation in an easily navigated

interface. Moreover, most optional settings have been

set to default values which will work in the majority

of cases. You can change options at any time and in

any order, often by using a RMB

pop-up menu.

The feature being created is identified by the

ribbon tab at the top of the dashboard -

Figure 24 The Extrude Dashboard

in this case an extrude. The dashboard contains two areas. On the left (Figure 24) are commands,

settings, and so on for the particular feature under construction. The ones showing are context

sensitive so with a different feature (like a hole) you will see different commands. The following

are for an extrude:

Solid and Surface buttons - these are an either/or toggle set. The default is to create a solid. If you

pick the next button, Surface, the sketch will be extruded as an infinitely thin surface (Figure

25). Return this to the Solid selection.

21

Figure 25 Extruded surface

Symmetric

To Selected

Blind

Figure 26 Depth Spec

options

Depth Spec Options - the next button is a drop-down list of all the possibilities for setting the depth

of the extrusion. These are indicated in Figure 26 (check out the tool tips). The default is a

Blind extrusion, which means the extrusion is for a fixed distance. Other options may appear

here as more part geometry appears (as in the cut which we will do next).

Blind Depth - this contains the numeric value of the length of the extrusion. If the depth

specification on the button to the left is not Blind, this text input area is grayed out.

Flip - selecting this will reverse the direction of the protrusion (the magenta arrow).

Remove Material - this allows you to change the meaning of the solid feature from a protrusion

(which adds solid material) to a cut (which removes solid material). Since there is nothing to

remove at this time, this command is grayed out - all we can do is add.

Thicken Sketch - press this to see the solid block replaced

by a thin-walled extrusion (formerly called a Thin

Solid). A new dimension appears in the graphics

window and on the dashboard. This is the thickness

of the solid wall. Try changing this thickness to

something like 2.0. On which side of the sketched

curve has this been added? Another Flip button has

also appeared. Press this a couple of times - it

controls which side of the sketch the material is

added to. Actually, it is a three way switch since you

can also add material equally on both sides of the

sketch. Press the Thicken button again to return to a

full solid protrusion.

Figure 27 A Thick extruded

solid

22

Just below this area of the dashboard are several pull-down areas which do the following:

Placement - allows you to select, create, or modify the 2D section to be used for the feature. Since

we preselected the sketched curve, it is now listed on this panel. If we had not preselected the

curve, we could have chosen it now, or launched Sketcher from this panel to create a new

sketch. This would involve selecting the sketching plane, sketcher reference, and so on. We

will go this route in the next feature. If you wanted to change the sketch for the extrude, this is

how you access it. The Unlink button is currently displayed on the Placement panel. This

button appears if, like now, you have preselected a curve to serve as the sketch for the extrude.

Thus, the extrude is linked to the previous curve feature; changes to the geometry or dimensions of

the curve would drive changes in the shape of the extrude. The curve itself is a separate entry on the

model tree. The purpose of unlinking is to break this (parent/child) connection to the original curve.

If you were to select this command (don’t do this now), the copy of the original curve stored in the

extrude feature would become independent. In that case, a change to the original curve would not

affect the extrude. The original curve could be modified, moved, or even deleted, and the extrude

would still be able to regenerate. The use of external curves to drive feature geometry is an

important aspect of an advanced modeling technique that makes use of skeleton models.

Options - information about the depth specification for the feature. We will find out what is meant

by “Side 2" in a later lesson. For a simple extrude, the depth specification is easiest to set

using one of the icons in the middle dashboard area (see below). Check out the Taper option

(drag on the white drag handle, return to 0 when done).

Properties - specify the name of the feature

As you explore the creation of new features in Creo Parametric you should investigate what is in

each of these menus. They are context sensitive, so there is a lot of variety in what you will find, but

all the dashboards basically operate the same way.

On the right end of the dashboard are several common tools that

appear for all features. See Figure 28. These function as

follows:

Pause - allows you to temporarily suspend work on this feature so

that you can, for example, create a missing reference like a

datum plane, measure something in the model, etc. When you

are finished with the side trip, press the symbol < that appears

here to continue where you left off.

Figure 28 Common

dashboard controls

Preview Options - (default = Attached) this is responsible for the shaded orange display of the

feature under construction. Select the No Preview button - all you will see is the feature

creation direction, drag handle, and depth dimension. Turn this back on.

23

View Geometry - this shows what the geometry will look like when the feature is fully integrated

into the part. Not much happens with this first protrusion. Press again to return to preview.

Accept and Quit - do just what you expect! Select

Accept (or middle click). The block now

appears, Figure 29, with its edges highlighted in green (last feature created).

We spent a lot of time discussing the creation of this

feature. Let’s create it again without all the discussion.

Select the Undo button at the top - this will delete the

protrusion. Now create it again:

T highlight the sketched curve

T select the Extrude tool

T change the depth to 30

T middle click.

You might open the Navigator pane to see the model

tree. The three default datum planes are listed. Then

Figure 29 Completed protrusion

comes the sketched curve Sketch 1 (hidden) and the extrude Extrude 1. Open the listing for the

extrude and you will see the internal sketch (also Sketch 1) that uses the hidden curve and is

currently linked to it. If you have used the Unlink button in the Placement panel, the model tree will

appear somewhat differently - the sketch stored inside the extrude is called S2D0001 and is

independent of Sketch 1. Close the Navigator.

We will now add another extruded feature - this time we will create a cut that removes material.

Furthermore, instead of creating the sketch first, as we did for the solid protrusion, we will create the

sketch within the feature itself. This will follow Method #2 of Table 2-2 back on page 9 of this

lesson. This is actually the more common way to use Sketcher. Before we do that, now is a good

time to save the part.

SAVING THE PART It is a good idea when you are just getting started to save your model quite frequently, just in case

something serious goes wrong. If you have to bail out of the program, you can always reload the

most recently saved copy of the part and continue from there.

There are (as usual!) several ways to save the part:

• in the Quick Access toolbar, select the Save button, or

• in the pull-down menus select File ' Save, or

• use the keyboard shortcut CTRL-S.

24

Make sure that the Save Object dialog is showing the desired working directory at the top. If not,

select it in the Common Folders area in the Navigator. At the bottom of the dialog window, the name

of the current active object (remember that you can have more than one object loaded into memory

at a time) should already be in view. Accept the default model name [block.prt] (this is the active

part) by pressing the enter key or the middle mouse button. Creo Parametric will automatically put

the part extension (prt) on the file. If you save the part a number of times, Creo Parametric will

automatically number each saved version (like block.prt.1, block.prt.2, block.prt.3, and so on). Be

aware of how much space you have available. It may be necessary to delete some of the previously

saved versions; or you can copy them to an archive location. You can do both of these tasks from

within Creo Parametric - we'll talk about that later.

IMPORTANT NOTE:

The Save command is also available when you are in Sketcher. Executing this command at that time

will not save the part, but it will save the current sketched section with the file extension sec. This

may be useful if the sketch is complicated and may be used again on a different part. Rather than

recreate the sketch, it can be read in from the saved file (using Data from File). In these lessons,

none of the sketches are complicated enough to warrant saving them to disk.

Now we will proceed on to the next feature - an extruded cut. Make sure nothing is currently

selected (highlighted) on the model (by clicking anywhere else in the window).

CREATING AN EXTRUDED CUT Following Method #2 of Table 2-2, start by launching

the Extrude command from the ribbon. The extrude

dashboard at the top of the screen opens. The Placement

pull-down panel tab is red to indicate missing

information there. Open it and select Define. The

Sketch dialog window appears. This time, however,

nothing has been preselected for us as it was for the

previous sketch. We’ll have to enter the data ourselves.

In the Sketch window, notice the slightly darker data

entry field, called a collector beside Sketch Plane. In

Creo Parametric, whenever one or more references can

be specified for something, they are placed into a

collector. When a collector is active (ready to accept

data) it is darker; otherwise it will be white.

Sketching Reference (TOP)

Sketching Plane

Figure 30 Setting up to sketch the cut

If you want to make a collector active, just click it.

Since the Sketch Plane collector is highlighted, the dialog is waiting for you to select the sketching

plane. Pay attention to preselection here. You will not be able to pick an edge

25

or a curved surface (both of these would be illegal). Pick on the right side surface of the block (see

Figure 30). As soon as you pick the sketching plane (it highlights in cyan), a magenta arrow will

appear showing the default direction of view relative to the surface. The Flip button can be used to

reverse this direction, but leave it as it is. Creo Parametric makes a guess at a potential reference

plane for you to use. This may depend on the current orientation of your view, and might result in a

strange view orientation in sketcher (like sideways or even upside down). We want to be a bit more

careful and specific here. The collector for the sketch reference surface is showing the default chosen

by Creo Parametric. To override the default for the active collector, pick on the top planar surface

(Figure 30), between the two tangent lines of the rounded corners; the surface will highlight in green.

In the Orientation pull-down list, select Top so that the reference will face the top of the screen. We

now have our sketch plane and reference set up, so select Sketch at the bottom of the dialog window.

So that we are looking straight on to the sketching plane, select the Sketch View button in the

Graphics toolbar.

We are now in Sketcher (Figure 31). Two references

have been chosen for us (the back and top surfaces of

the object). We are going to create the U-shaped figure

shown in Figure 32. Note that there is no sketched line

across the top of the U - there is no inside or outside.

Thus, it is technically called an open sketch (as

opposed to a closed sketch for our previous feature).

There are some restrictions on the use of open sketches

which we will run across in a minute or two.

You might prefer to set your display mode to Hidden

Line at this point.

Sketch reference

Sketch reference

Figure 31 References for

cut sketch

Use the RMB pop-up menu to select the Line 1 Chain command. Start your sketch at vertex 1 in 4 Figure 32 - the cursor will snap to the reference.

Then drag the mouse down and pick vertex 2 (note

the V constraint), and middle click twice to end the

Line command. Some weak dimensions will appear.

Do nothing about them yet because, since they are

weak, they are liable to disappear anyway. If we

make them strong, this will cause us extra work

dealing with Intent Manager. The line is

highlighted in green. Left click somewhere else to 2 3 deselect the line.

Figure 32 Sketch geometry

26

Helpful Hint

Wait until the shape of the sketch is finished before you start worrying about the

dimensioning scheme or dimension values.

Use the RMB pop-up menu again and select the 3-Point/Tangent End command. Pick on the end of

the sketched line (vertex 2) and drag the mouse downwards in the direction of tangency. Once the

arc has been established, drag the cursor over to the right (the arc will rubber-band while

maintaining the tangency constraint) and click at vertex 3. (If you drag straight across to vertex 3

you will get a 3-point arc which is not automatically tangent at vertex 2.) You should see two small

blips that indicate when vertex 3 is at the same height as the center of the arc. Left click to create the

vertex 3. Use the RMB menu to pick Line Chain again.

Now left click at vertex 3 and draw a vertical line up to snap to the reference at vertex 4, making

sure that you have a tangent constraint (T) at vertex 3. Our sketch is complete. Use the middle

mouse button to return to Select mode. Your dimension values may be different from those shown in

Figure 33. Your dimensioning scheme may even be slightly different. It will be easier to see this if

you go to hidden line display instead of shading.

All the dimensions should be weak. Drag them to a better location if necessary (off the part). Don’t

be afraid to resize your display so that you can see everything clearly. Compare the dimensioning

scheme with the one in Figure 33. We want to have a horizontal dimension of 15 from the reference

at the back of the part to the center of the arc of the U. If you do not have that dimension, we’ll have

to add one manually. This will illustrate a case where we will override the Intent Manager.

To create your own dimension, select the Normal

command from the Dimension group (or Dimension in

the RMB pop-up). Click on the vertex at the center of

the arc (it will highlight) then click again on the dashed

reference line at the right. Now middle click in the

space above the part where you want the dimension

text to appear. Set the value as shown in the figure.

It’s that easy! Note that this dimension shows

immediately in dark blue since it is strong. One of the

weak linear dimensions should be gone. Middle click

to get back to Select.

Figure 33 Final sketch for cut

We now have the references, shape, implicit constraints and dimensioning scheme we want. So

now we can worry about the dimension values. Get in the habit of dealing with your sketches in

the following order:

27

References º

Shape º

Constraints º

Dimension scheme º

Dimension values

Modify the values of the dimensions to match those in Figure 33.

Recall the hint above about open vs closed sketches. The sketch we have just produced will be able

to produce the desired cut, but it is not the best we can do. The behavior of features constructed

using open sketches is unpredictable. The danger lies in the possibility that something or someone

may come along later to modify this part and add something to the top of the block earlier in the

model tree. In that case, the cut feature would likely fail due to the uncertainty in what to do across

the open ends of the sketch. So before we accept this sketch, let’s explore the diagnostics a bit.

Helpful Hint

In general, try to keep your sketches closed - you will have fewer problems that way.

Open sketches will be necessary only for special features or modeling requirements.

First, turn on the Shade Closed Loops and Highlight Open Ends buttons. Since the sketch is

currently open it will not shade; the two ends will show the red dots. Create a line across the top of

the sketch to close it (use Line Chain in the RMB popup). Now the sketch will shade, the red dots

disappear. The sketch is now complete, so click on the OK button in the toolbar7. If you are in

hidden line display, return to shading display.

The feature will now be previewed. A couple of new buttons have appeared on the dashboard.

First, in the Depth Spec pull-up list, there are a few more options available (Figure 34). For this

cut, we would like the sketch to be extruded through the entire part, so pick the Through All

option. Note that the dimension for a blind extrusion disappears from the screen. To the right of

this area, click the Flip button to make the extrusion go through the part. The Remove Material

button needs to be selected - finally we indicate that we are making a cut. Now, there are two

magenta arrows attached to the sketch. The one perpendicular to the plane of the sketch shows the

direction of the extrusion. The other shows which side of the sketched line we want to remove

material from. These should be set as shown in Figure 35.

7 This is one of the few times when a middle click does not mean “Accept”, which is a

good thing since inadvertent middle clicks happen often when you are in Sketcher.

28

Now select the Verify button in the right area of the dashboard. If you have the Remove

Material button set wrong, Creo Parametric will create a protrusion instead of a cut8. Turn Verify

off.

Blind

Symmetric To

Next Through

All

Through Until

To Selected

Figure 34 More Depth Spec

options in the dashboard Figure 35 Defining cut attributes (direction and material removal side)

Another common error with cuts is having the material removal side set wrong (the second

magenta arrow in Figure 35). If you do that for this part, you will end up with Figure 36. Make

sure the material removal arrow points to the inside of the U. Plus, you should explore the

Placement, Options, and Properties menus on the dashboard before you leave.

We are finished creating this feature, so select the Accept button at the right end of the dashboard.

The part should now look like Figure 37 when in default orientation. The cut will be highlighted in

green as usual, as the last feature created.

Save the part (Ctrl-S). We will need it in this condition for the next chapter.

8 Even worse, if we had left the sketch open, the feature would fail and you would be launched into

a Troubleshooter dialog window. The source of this problem is the open sketch for the U. This

sketch is ambiguous since when the sketch starts out from the sketch plane, the vertices at the ends

are out in the open air; Creo Parametric would not know how to create the solid to attach it to the

existing part. This problem does not occur with a cut as long as the open ends of the sketch stay

outside or on the surface of the part. You might come back and explore this later.

29

Figure 36 Removing from the

wrong side of the sketch Figure 37 Cut feature

completed

USING PART TEMPLATES You will recall that in the block part created earlier, the first thing we did was to create default

datum planes. These (plus the named views based on them, which we didn’t create this lesson) are

very standard features and aspects of part files, and it would be handy if this was done

automatically. This is exactly the purpose of part templates.

A template is a previously created part file that contains the common features and aspects of almost

all part files you will ever make. These include, among other things, default datum planes and

named views. Creo Parametric actually has several templates available for parts, drawings, and

assemblies. There are variations of the templates for each type of object. One important variation

consists of the unit system used for the part (inches or millimeters). Templates also contain some

common model parameters and layer definitions9.

A template can be selected only when a new model is first created. Let’s see how that works. Create

a new part (note that you don’t have to remove the block - Creo Parametric can have several parts

“in session” at the same time) by selecting

File ' New

or using the “Create New Object” button in the Quick Access toolbar. The New dialog window

opens. The Part | Solid options are selected by default. Enter a new name, like exercise_1. Remove

the check mark beside Use default template (we normally don’t do this, but we should have a look

at what is available) and then select OK.

9 Model parameters and layers are discussed in the Advanced Tutorial.

30

In the New File Options dialog window, the default template is shown at the top. It is likely

“inlbs_part_solid” (unless your system has been set up differently). This template is for solid parts

with the units set to inch-pound-second. It seems strange to have force and time units in a CAD

geometry program. Actually, this is included so that the part units are known by downstream

applications like Creo Simulate which perform finite element analysis (FEA) or mechanism

dynamics calculations. These programs both require force, mass, and/or time in their operation and

are very picky about units!

Note that there are templates available for metric units (millimeter-Newton-second). While we are

mentioning units, be aware that if you make a wrong choice of units here, changing units of a part is

possible after it has been created (see File ' Prepare ' Model Properties).

There are only two model parameters in the default template. DESCRIPTION is for an extended title

for the part, like “UPPER PUMP HOUSING”. This title can (eventually) be called up and placed

automatically on a drawing of the part using, you guessed it, a drawing template. Similarly, the

MODELED_BY parameter is available for you to record your name or initials as the originator of the

part. Fill in these parameter fields (“Creo Exercise #1" and your initials) and select OK.

The new part is created which automatically displays the default datums. They are even named for

you (we will see how to name features in lesson 3): instead of DTM1, we have RIGHT. TOP

replaces DTM2, and FRONT replaces DTM3. The part also contains a coordinate system, named

views (look in the Named Views List), and other data that we’ll discover as we go through the

lessons. The named views correspond to the standard engineering views. Thus, it is important to

note that if you are planning on using a drawing template that uses these named views, your model

orientation relative to the default datums is critical. The top-front-right views of the part are the ones

that will be automatically placed on the drawing later. If your model is upside down or backwards in

these named views, then your drawing will be too.

Now, having created this new part, you are all set up to do some of the exercises at the end of the

lesson. Do as many of these as you can. Perhaps do some of them in different ways by

experimenting with your sketch orientation, Sketcher commands, and so on.

aed lab

Documents

lab timetable

lab supervisor report

lab premises clean

elements of drawing

drawing environment

drawing sheet layout

laboratory session

acad basics