Autocad 2d Module 28 PDF

8/14/2019 Autocad 2d Module 28 PDF

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Learning Outcomes:

AutoCAD Self-paced Learning Modules

AutoCAD 2DModule 28

Regular Polygons

When you have completed this module, you wil l be able to:

1. Describe an AutoCAD regular polygon and the methods used to construct them.

2. Describe and apply the POLYGON, RECTANGLE, ELLIPSE and AREA commands.

Drawing Regular Polygons

In AutoCAD, a regular polygon is a closed polyline having between 3 and 1,024 equal-length

sides and is drawn using the POLYGON command. Using the POLYGON command to createpolygons is a fast and simple way to draw squares, equilateral triangles, hexagons, octagons,and any other regular polygon. See Module 14, page 14-1.

The POLYGON command constructs a closed polygon using the inscribed, circumscribed or the

edge method, as shown in Figure 28-1. Since the polygon drawn by the POLYGON commandis a polyline, it is one object in AutoCAD. It It can be exploded into individual lines using theEXPLODE command.

Even though a square can be constructed using the POLYGON command, they can also be

drawn with the RECTANGLE command.

Figure 28-1

Methods of Drawing Regular Polygons

Regular Polygons The CAD Guys Ltd. Copyright 1993 - 2007 Module 28
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28 - 2 AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-13

AutoCAD Command: POLYGONThe POLYGON command is used to create closed regular polylinesto form polygons that have between 3 to 1024 sides.

Shortcut: POL

2004-2008

2000-2002

AutoCAD Command: RECTANGLEThe RECTANGLE command is used to construct a 4 sided polygonusing a closed polyline in the shape of a rectangle or a square.

Shortcut: REC

2004-2008

2000-2002

AutoCAD Command: ELLIPSEThe ELLIPSE command is used to construct ellipsesor elliptical arcs.

Shortcut: EL

2004-2008

2000-2002



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-13

Geometry Lesson

Ellipse

An ellipse is determined by two axes that define its length and width. The longer axis is

called the major axis, and the shorter one is the minor axis. The axes intersect at the

28 - 3

center of the ellipse. The rotation angle of the ellipse determines length of the minor axiscompared to the length of the major axis. See Figure 28-2.

Figure 28-2

An Ellipse

Object Snap Modes for an Ellipse

Mode

Center

Quadrant

Abbreviations

Cen

Quad

Icon Marker The AutoCAD Object

While the ELLIPSEcommand can be used todraw elliptical arcs, it is mucheasier to draw full ellipses

and then trim or break them to the desiredsize.

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Using the POLYGON, RECTANGLE and ELLIPSE Commands

Step 1 Start a new drawing using the template Module Template A.

Step 2 Save and name the drawing AutoCAD

2D Workalong 28-1.

Step 3 Create layers Object and Construction

as shown in Figure Step 3.

Step 4 The border of the template

drawing is constructed using a Pline.

Using the EXPLODE command, explode

the border into its 4 lines as shown inFigure 4A. Check to ensure it isexploded by selecting one line as shownin Figure Step 4B.

Figure Step 4A

Figure Step 3

Figure Step 4B

Step 5 Offset the left border line 3 times at a distance of 2 units. Offset the top border

lines 3 times at a distance of 1.5 units as shown in Figure Step 5.

Step 6 Change the layer of the offset lines to layer

Construction. Trim the lines and your drawing shouldappear as shown in Figure Step 6.

Figure Step 6

...continued on page 28-5

Regular Polygons The CAD Guys Ltd. Copyright 1993 - 2007

Figure Step 5

Module 28


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Using the POLYGON, RECTANGLE and ELLIPSE Commands - Continued

Step 7 Enter the POLYGON command

shown below to draw a hexagon with itscenter at the intersection of the top and

the left line as shown in Figure Step 7Aand 7B.

Command: POL

Enter number of sides : 6

(Enter the number of sides of the polygon.) Figure Step 7B

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Specify center of polygon or [Edge]: (int)(Snap to the intersection of the two lines.)

Figure Step 7A

Enter an option [Inscribed in circle/Circumscribed about circle] : I(This is an inscribed polygon since it is dimensioned by a circle that it is located inside.)

Specify radius of circle: .5(Radius of the inscribed circle.)

Command:

Step 8 Enter the POLYGONcommand shown below to draw ahexagon with its center at theintersection of the top and the centerline as shown in Figure Step 8A and8B.

Command: POL

Enter number of sides : 6(Enter the number of sides of the polygon.)

Specify center of polygon or [Edge]: (int)(Snap to the intersection of the two lines.)

Figure Step 8AFigure Step 8B

Enter an option [Inscribed in circle/Circumscribed about circle] : C

(This is a circumscribed polygon since it is dimensioned by a circlethat is located inside it.)

Specify radius of circle: .5(Radius of the circumscribed circle.)

Command:

Step 9 Enter the POLYGON command shown below to

draw a hexagon with its center at the intersection of the topand the right line as shown in Figure Step 9A and 9B.

Command: POL

Enter number of sides : 6Specify center of polygon or [Edge]: (int)Enter an option [Inscribed in circle/Circumscribed about circle] : I

Specify radius of circle: @.5


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Figure Step 10A

Step 10 Using what you learned in Steps 7

to 9, draw the three polygons shown in FigureStep 10A and Step 10B.

Figure Step 10B

Figure Step 11

Command: RECTANGLESpecify first corner point or

Step 11 On layer Object, enter the RECTANGLE

command shown below to draw the rectangle shownin Figure Step 11.

[Chamfer/Elevation/Fillet/Thickness/Width]: 1,2.5Specify other corner point or

[Area/Dimensions/Rotation]: 7.5,6Command:

Step 12 On layer Construction, draw diagonal

lines from corner to corner of the rectangle asshown in Figure Step 12.

...continued on page 28-7Figure Step 12



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Step 13 On layer Object, enter the ELLIPSE

command shown below to draw the ellipse shown inFigure Step 13A and 13B.

Command: ELLIPSE

Specify axis endpoint of ellipse or [Arc/Center]: CSpecify center of ellipse: (int)

(Snap to the intersection of the two diagonal lines tolocated the center of the ellipse.)

Specify endpoint of axis: @2,0

Specify distance to other axis or [Rotation]: @0,1 Figure Step 13ACommand:

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Figure Step 13B Figure Step 14

Step 14 Trim the diagonal lines from inside the ellipse as shown in Figure Step 14.

Figure Step 15A

Step 15 Draw the four polygons shown in

Figure Step 15A and Step 15B. Locate the

center of the polygon on the midpoint of eachconstruction line.


Regular Polygons

Figure Step 15B

The CAD Guys Ltd. Copyright 1993 - 2007 Module 28


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Step 16 Enter the POLYGON command shown below to draw a hexagon using the edge

method. See Figure 16A and 16B.

Command: POL

POLYGON Enter number of sides : 6

Specify center of polygon or [Edge]: E

Specify first endpoint of edge: (end) P1

Specify second endpoint of edge: (end) P2Command:

Figure Step 16A

Step 17 Explode both polygons and delete the lines they

share as shown in Figure Step 17.

Figure Step 16B

Figure Step 17

Step 18 Using the PEDIT command, create a closed

polyline as shown in Figure Step 18.

Step 19 Using the Properties dialogue box, confirm

the polygon you just created in Step 18 is closed.Your drawing should now appear as shown in FigureStep 19.


Figure Step 18

Figure Step 19



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AutoCAD Command: AREAThe AREA command is used to find the area or perimeter of a series of coordinates, a closedpolyline, circle or ellipse.

Shortcut: none

2004-2008

2000-2002

Using the AREA Command

Step 20 Enter the AREA command shown below to measure the area of the rectangle

using the Corner Point method. See Figure Step 20.

Command: AREA

Specify first corner point or [Object/Add/Subtract]: (end) P1

Specify next corner point or press ENTER for total: (end) P2Specify next corner point or press ENTER for total: (end) P3Specify next corner point or press ENTER for total: (end) P4Specify next corner point or press ENTER for total:

28 - 9

(You do not have to snap back to the start point. The AREA command will go back to the first pointand calculate the area and perimeter.)

Area = 22.7500, Perimeter = 20.0000Command:

(This is an example of using the point methodof finding the area and the perimeter of a

series of coordinate locations.)

Authors Comments:

The corner point method only works for anarea containing line. It does not work ifany one of the sides is an arc.


Regular Polygons

Figure Step 20

The CAD Guys Ltd. Copyright 1993 - 2007 Module 28


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Using the AREA Command - Continued

Step 21 Enter the AREA command shown below to measure the area and perimeter of

the rectangle using the Object method. SeeFigure Step 21.

Command: AREA

Specify first corner point or [Object/Add/Subtract]: O(Using the Object method.)

Select objects: P5(Select the object. It must be a closed polygon, acircle or an ellipse.)

Area = 22.7500, Perimeter = 20.0000Command:

Step 22 Enter the AREA command shown Figure Step 21

below to measure the area of the rectangle subtracting objects from the overall area. SeeFigure Step 22.

Command: AREASpecify first corner point or [Object/Add/Subtract]: A

(Specifying you want to be in Add mode. That means the area command will add all the areas together

while in this mode.)

Specify first corner point or [Object/Subtract]: O

(ADD mode) Select objects: P6(Add in the rectangle area.)

Area = 22.7500, Perimeter = 20.0000

Total area = 22.7500

(ADD mode) Select objects:(Press enter to end the Add mode)

Specify first corner point or [Object/Subtract]: S(Beginning the Subtract mode.)

Specify first corner point or [Object/Add]: O

(SUBTRACT mode) Select objects: P7Area = 0.1591, Perimeter = 1.8187Total area = 22.5909(SUBTRACT mode) Select objects: P8Area = 0.3183, Perimeter = 2.1000Total area = 22.2726(SUBTRACT mode) Select objects: P9Area = 6.2832, Perimeter = 9.6884Total area = 15.9894(SUBTRACT mode) Select objects: P10Area = 0.6365, Perimeter = 3.5000Total area = 15.3529(SUBTRACT mode) Select objects: P11

Area = 0.2450, Perimeter = 1.9799Total area = 15.1079(SUBTRACT mode) Select objects:

(Press Enter to end the Subtract mode.)

Specify first corner point or [Object/Add]:(Press Enter to complete the command.)

Command:


Figure Step 22



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Using the AREA Command - Continued

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Step 23 Enter the AREA command shown below to measure and add the areas of three

individual objects. See Figure Step 23.

Command: AREA

Specify first corner point or [Object/Add/Subtract]: A(Enter the Add mode.)

Specify first corner point or [Object/Subtract]: O

(ADD mode) Select objects: P12Area = 0.1591, Perimeter = 1.8187Total area = 0.1591(ADD mode) Select objects: P13Area = 0.2450, Perimeter = 1.9799Total area = 0.4041

(ADD mode) Select objects: P14Area = 0.6365, Perimeter = 3.5000Total area = 1.0407

(The total area of the three objects combined is

1.0407 square units. In this case square inches.)(ADD mode) Select objects:Specify first corner point or [Object/Subtract]:Command:

Authors Comments:

The area and perimeter canalso be obtained by usingthe Properties window. Itmust be a closed polygon.

Step 24 Open the

Properties window andselect the large rectangle asshown in Figure Step 24.The area and the perimeter(length) will display.

Step 25 Now deselect the

rectangle and select theobject in the bottom right asshown in Figure Step 25. Thearea and the perimeter

(length) will display as shown.

Step 26 Save and close the

drawing.

Figure Step 23

Figure Step 24

Figure Step 25



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Geometry Lesson

Degrees Minutes and Seconds

Since a full degree is not always precise enough to measure an angle, you must be able to

work to a more precise measurement. Degrees are broken down to smaller and more

precise units ofminutes andseconds.

1 degree is divided into60 minutes and 1 minuteis divided into 60seconds:

1 degree = 60

minutes1 minute = 60secondsTherefore, 1 degree =3600 seconds.

Degrees are written 1,minutes are written 01'and seconds 01". Put

them together: 1


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Working in Degrees Minutes and Seconds

Up to this point in the modules you have been

entering angles with decimal degree valuesonly. In this module, you will learn how toenter angles with degree/minutes/seconds.

First, you much change the way AutoCAD

reports angular units and precision. You dothat with the UNITS command. Please notethat you only set the UNITS command tochange the way AutoCAD reports angles toyou. You do not have to set the UNITScommand to enter degree/minutes/seconds.Study the Drawing Units dialogue box. TheAngle Type must be set to Deg/Min/Sec andthe Precision set to the value you wantreported. See Figure 28-3.

Since there is no degree symbol on the Figure 28-3

28 - 13

keyboard, you must enter the degree valueusing the letter d after the number.For example: 34d

To specify the number of minutes, enter a ' (single

quote) after the number and to enter seconds, entera " (double quote) after the number. See Figure28-4.

For example: 34d56'32"

Command: LINESpecify first point: 2,2

Specify next point or [Undo]: @2


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Lab Exercise 28-1

Drawing Specifications

Time Allowed: 60 Min.

Name

AutoCAD 2D Lab 28-1

Template

Module Template B

Units

Inches

Text Style

N/A

Font

N/A

Objects on Layer Name

Layering Scheme

Color Linetype Lineweight

Construction Objects

All Objects

Construction

Object

253

Red

Continuous

Continuous

N/A

N/A

Text in the Titleblock

Polyline

Instructions:

Titleblock text

Outline

White/Black Continuous

Blue Continuous N/A

1. Draw the object shown below.

Completed Drawing



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2. On layer Outline, create a closed polygon of the

outside outline of the object as shown in Figure Step 2.

Find all answers to questions 3 and 5 to a precision of 8decimal places.3. Find the area and perimeter of the outline of the object

as shown in Figure Step 2.

Area = ___________________________

Perimeter = ______________________

Figure Step 2

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Figure Step 4

4. Change the square and the heptagon to appear as

shown in Figure Step 4. Create a closed polygon of thenew shape of Figure Step 4.

5. a) Find the area of the outside area minus all

the objects on the inside.

Area = ___________________

b) Find the area of all the objects on the inside.

Area = ___________________

c) Add the area of 5A and the area of 5B. This

should equal the area found in question 3.

Area = ___________________

Construction Hints

Do your best to complete the lab exercise drawing

without using the following hint(s). If you get stuck andcan't complete it on your own, use the following hint(s)to help you.

Hint 1

To draw the 3 R tangent arc on the top right side of the

object you must draw a tangent circle and then trim it.

AutoCAD will not draw it using the FILLET commandsince it wants to draw the fillet on the inside. Use theCIRCLE command and the TTR option to insert thetangent circle.

Figure Step 5

Figure Hint 1



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Lab Exercise 28-2

Drawing Specifications

Time Allowed: 60 Min.

Name

AutoCAD 2D Lab 28-2

Template

Module Template C

Units

Feet

Text Style

N/A

Font

N/A

Objects on Layer Name

Layering Scheme

Color Linetype Lineweight

Construction Objects

Map Lines

Map Dimensions

Construction

Map

Map Dimension

253

Red

Cyan

Continuous

Continuous

Continuous

N/A

N/A

N/A

Map Lot Size Text Map Notes White/Black Continuous N/A

Map Text Map Text 200 Continuous N/A

Text in the Titleblock

Instructions:

Titleblock Text White/Black Continuous N/A

1. Since the object you will be drawing is large, you will have to scale the drawing titleblock larger.Complete the following steps:a) Start a new drawing using the Module Template C.

b) Using the SCALE command, and the base point of 0,0, scale the complete titleblock and border toa scale factor of 100. In a future module, there will be a complete explanation of why this numberis used. For now, just use the number given to you.

2, Draw the map shown on page 28-12. The input is feet and decimals of a foot. Set the Length Type to

Decimals in the UNITS command.3. Add the length of the lot lines along each lot as shown on the map. Pick a good height with the text

style Map with the font Arial.4. Place the lot numbers and the street names on layer Map Text.5. Fill in the titleblock as shown.

Mini Survey Plan Lesson

The length of the lots, on survey maps, is dimensioned by placing the length parallel and along the lot l ineit is referring to. The length is measured from corner of lot to corner of the lot. In the example above, thedistance is 500.0 feet. The pin, small circles at the ends, have nothing to do with the dimensions. Theyonly show where the surveyor has placed a metal pin in the ground when the survey was completed.When you draw the map, draw all the lines and then insert circles of 10 feet dia. at the ends of the lines.



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AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-13 28 - 17

6. Find the area of each lot to two decimal places and place the text on the drawing using the example

below as a guide. Pick a good text height using the text style Map you created earlier. Place it on layerMap Notes.

Completed Drawing



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Construction Hints

Do your best to complete the lab exercise drawing without using the following hint(s). If you get

stuck and can't complete it on your own, use the following hint(s) to help you

Hint 1

To draw the arc in the center, first draw two 150 diameter circles on layer Construction. Use

the ends of the lot lines as the center location. See Figure Hint 1A. Where the circles intersectis the center of the 150 diameter arc. Draw a circle and then trim it. See Figure Hint 1B.

Hint 2

Figure Hint 1A Figure Hint 1B

Figure Hint 2A to 2E will help you with the calculating the angles.

Figure Hint 2A

Figure Hint 2B



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Regular Polygons


Figure Hint 2C

Figure Hint 2D

Figure Hint 2E

The CAD Guys Ltd. Copyright 1993 - 2007

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Module 28

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