Autocad 2d Module 09 PDF

8/14/2019 Autocad 2d Module 09 PDF

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Learning Outcomes:

AutoCAD® Self-paced Learning Modules

AutoCAD 2DModule 9

Controlling the Drawing

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

1. Describe drawing limits, extents, scale, and units.

2. Describe and apply the commands ZOOM, PAN, REGEN, and VIEWRES to control thedrawing.

Controlling the Drawing

Since the AutoCAD drawing is where you will be working mostof the time, it is important for you to understand how it worksand be able to control it to work for you rather than againstyou. In this module, limits, extents, scale, units, zooming,panning, and regenerating are covered.

Drawing Limits

The drawing limits are always a rectangular or square shape

representing the drawing size. Simply, you can think of themas the size of the piece of paper you are drawing on. Theycan be any size you wish and the size can be changed at anytime. The template files that you have been using in your labexercises already have the limits set for the drawing.

Once set, all objects

should be drawn inside thelimits although it is

Figure 9-1

The Drawing Limits

Figure 9-2

The Drawing Extents

possible to draw outside of them and there are times youmust do just that. They are more of a guide and are usefulin plotting and working with grids as you will see in futuremodules.

Drawing Extents

The drawing extents is the smallest rectangle that will fit

around all the existing objects in the drawing. It is possibleto draw outside the drawing limits and; therefore, anobject(s) that is outside the limits may not be visible in thenormal drawing display. By being able to display thedrawing extents, you will be able to see all of the objectsthat exist in the drawing.

Controlling the Drawing The CAD Guys Ltd. Copyright © 1993 - 2007 Module 9

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9 - 2 AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11

Since AutoCAD allows a drawing to be very large, an object(s) is sometimes placed, byaccident, somewhere out in space. This can severely derogate the performance of the drawing.Sometimes the only way to work on a drawing that is derogated is to find the erroneousobject(s) and erase it.

If you are attempting to find all the existing objects by displaying thedrawing extents, ensure that all layers are visible and are not frozen or off.

Drawing Scale

The general rule, when drawing with a CAD system, is to always draw everything full scale or

full size. Almost all the time scaling the drawing is done when it is plotted as you will see infuture modules.

Always draw everything in full scale or full size regardless of its size. All

scaling is done when the object is plotted.

Drawing Units

AutoCAD drawings are unitless. In other words, if you enter a unit of 1 into your drawing and

the drawing was originally created in inches, then the 1 means 1 inch. From that point forward,all units entered into that drawing must be entered as inches. If in a second drawing, theoperator creates a drawing and picks the units to be millimeters, then all numbers entered inthat drawing are in millimeters.

To sum up, when a drawing is first started, the operator must make a decision as to what units

will be used for that drawing. There are ways to change the units of a drawing but you willlearn how to do that in a later module.

AutoCAD drawings are unitless. The operator who creates the drawing

makes the decision of what units will be used for the new drawing. Fromthat point forward, all units must be entered in those units.

AutoCAD Command: LIMITSThe LIMITS command is used to set the limits for the drawing.

Shortcut none






AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11 9 - 3

The lower left corner of the limits of the drawing should always be set at 0,0

or X0,Y0.

Zooming and PanningZooming

Zooming is the process of moving the drawing closer or further away from your eyes without

actually changing the size of any existing objects. It is an important tool for the AutoCADOperator and is used extensively in the drawing process. Drawings can be very large and

therefore you must be able to zoom in to see what you are doing and back out again to workwith the overall drawing. As you do this, you are not changing the size of the objects, you aresimply adjusting the distance the objects are from your eyes.

AutoCAD Command: ZOOM

The ZOOM command is used to move theexisting objects closer or farther away fromyour eyes without changing their physical size.

Shortcut: Z

2004-2008

2000-2002

2004-2008

2000-2002







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Panning

AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11

If you have a mouse with a wheel as the center button, you can use it tozoom in and out of your drawing by rotating the wheel forward or backward.Using the wheel to zoom will increase your drawing speed greatly. If youdon't have a wheel mouse, you must use commands to accomplish thesame thing.

Panning is the process of moving the drawing around the computer screen without actually

physically moving any of the objects on the drawing. The best way to do this is with the middlebutton (wheel) of your mouse. If you have a wheel mouse, move the graphic cursor to thelocation you are currently working on and push the middle button down and hold it. A cursor shaped like a hand will replace the graphic cursor. Move the hand and the drawing will pan withit. If you don't have a wheel mouse or a three button mouse, you can use the PAN command.

AutoCAD Command: PANThe Pan command is used to move the drawingaround the computer screen.

Shortcut: P

2004-2008

2000-2002

If you have a mouse with a wheel as the center button, you can use it topan your drawing. Move the cursor to the part of the drawing you wantto pan and press down on the wheel. A Pan Hand icon will display as thegraphic cursor. While holding down the wheel, you can move the mouseto pan the drawing. Using the wheel to pan will increase your drawingspeed greatly. If you don't have a wheel mouse, you must use the PANcommand to accomplish the same thing.







The ZOOM Previous command allows you tostep back through the previous zoomedstates. This allows you to quickly zoom in onan object, draw or edit and then return backto the previous zoomed state.

Regenerating the Drawing

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AutoCAD stores all existing objects and their properties in a database format in the .DWG file.

When you open a drawing, AutoCAD must open the .DWG file and rebuild the objects one attime displaying them onto the computer screen.

There are times you are required to rebuild your drawing from the .DWG file. This is called

regeneration. There are many reasons for regeneration and they will become clear to you asyou work your way through the AutoCAD Modules. Some AutoCAD commands regenerate thedrawing automatically, but not all of them. Therefore, it is up to you to execute the REGENcommand to force AutoCAD to display the results of the previous command.

AutoCAD Command: REGENThe REGEN command rebuilds all drawing objects from the .DWGfile and displays them on the screen.

Shortcut: RE

AutoCAD Command: VIEWRESThe VIEWRES command sets the number of lines that AutoCAD builds when it regenerates thecircles and arcs in the drawing.

Shortcut: none

Using the LIMITS, ZOOM, PAN, REGEN and VIEWRES Commands

Step 1 Open the drawing AutoCAD 2D Workalong 08-1 that youcompleted in Module 8. If you have not completed that drawing,go back to Module 8 and do it before continuing on with this

workalong.

...continued on page 9-6Drawing AutoCAD 2D

Workalong 08-1








Using the LIMITS, ZOOM, PAN, REGEN and VIEWRES Commands - continued

Step 2 Enter the LIMITS command and set the limits of the drawing as shown below.

Command: LIMITS

Reset Model space limits:Specify lower left corner or [ON/OFF] <0.0000,0.0000>:

(Press enter to leave the lower left corner at 0,0. In most cases, it is best to leave the lower left corner at 0,0)

Specify upper right corner <12.0000,9.0000>: 8.5,11

(Set the upper right corner to X8.5,Y11. That is the size of the drawing)Command:

Step 3 Enter the CIRCLE command shown below to draw a 1 diameter circle with itscenter at X10Y12.

Command: C

CIRCLE Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 10,12

Specify radius of circle or [Diameter]: DSpecify diameter of circle: 1

Command:

Step 4 Enter the ZOOM EXTENTS command as shown in

Figure Step 4A. Your drawing should now appear asshown in Figure Step 4B. The extents of the drawing isnow displayed.

Figure Step 4B

Figure Step 4A

Step 5 Enter the CIRCLE command shown below to draw a 1 diameter circle with its

center at X-50,Y-50.

Command: C

CIRCLE Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: -50,-50

Specify radius of circle or [Diameter]: D

Specify diameter of circle: 1

Command:

..continued on page 9-7

At times, you are required to regenerate your drawing from the .DWG file.

Drawing regeneration is accomplished with the REGEN command. If youare in doubt about the current appearance of your drawing, regenerate it.








Step 6 Enter the ZOOM EXTENTS command

again. Your drawing should appear as shown inFigure Step 6. Note that the extents of the drawing

is now larger therefore the drawing will appear smaller and show both circles.

Step 7 Delete the two

circles that you inserted inStep 3 and Step 5. Enter theZOOM EXTENTS commandagain. The titleblock andborder of the drawing should

now fill the graphic window as

9 - 7

Figure Step 7

shown in Figure Step 7. Figure Step 6

Step 8 Using either the wheel on the mouse or the ZOOM

WINDOW command, zoom the objects in the drawing to fill thegraphic window as shown in Figure Step 8.

Step 9 Enter the VIEWRES command shown below. Always

answer Y to fast zooms and enter 20000 as the circle zoompercent. Enter the REGEN command to regenerate thedrawing.

Command: VIEWRES

Do you want fast zooms? [Yes/No] <Y>: Y

Enter circle zoom percent (1-20000) <2000>: 20000Command:

Command: REGEN

Regenerating model.

Author's Comments:

Figure Step 8

The only object AutoCAD can construct in any drawing is a line. Even circles and arcs are

constructed using many lines connecting two XY coordinate points that are calculated eachtime the drawing is regenerated. The more lines AutoCAD uses to construct the circles andarcs, the smoother or more circular they will display. The VIEWRES command sets the

zoom percentage of the lines that AutoCAD uses when it constructs or regenerates thecircles and arcs in the drawing. In this example, the VIEWRES was set to 20000 whichmeans that the circles and arcs will appear very smooth. On the other hand, it will takeAutoCAD much longer to calculate that many points for each circle and arc. You have totake all of this into account when you are setting the viewres for each drawing.

...continued on page 9-8









Step 10 Enter the commands shown below.

Command: VIEWRES

Do you want fast zooms? [Yes/No] <Y>: Y

Enter circle zoom percent (1-20000) <2000>: 8Command:

(By setting the VIEWRES to 8, you can see on the drawing that the

circles appear as a polygons. See Figure Step 10A.)

Figure Step 10ACommand: VIEWRESDo you want fast zooms? [Yes/No] <Y>: Y

Enter circle zoom percent (1-20000) <20000>: 2000

Command: REGEN

Regenerating modelCommand:

(By setting the VIEWRES to 2000, you can see on the drawing that

the circles appear smooth again. See Figure Step 10B.)

Step 11 Save and close the drawing.

Figure Step 10B

The ZOOM EXTENTS is a very important command and if used when

required, can prove to save you a lot of time and effort. When you firstopen a drawing, especially one that was drawn by someone other thenyourself, the first thing you should do is ensure that all layers are on and

thawed. Then enter the ZOOM EXTENTS command. Doing this will show you the size andscope of the drawing before you do any work on it.

Since the ZOOM EXTENTS command is used a lot during the drawing

process, there is a shortcut to execute this command. Move the cursor tosomewhere on the graphic window and double click the wheel or middlebutton on the mouse.

The Key Principles in Module 9

1. The drawing extents is the smallest rectangle that will fit around all the existing objects in

the drawing.

2. Always draw everything in AutoCAD at full size.

3. AutoCAD drawings are unitless. The operator who creates the drawing makes the

decision what units will be used for that drawing.

4. When a drawing is regenerated, AutoCAD reconstructs the drawing from the .DWG file.

Drawings regenerate when they are opened but you can force a drawing to regenerate

with the REGEN command. There are many instances that you will be required toregenerate the drawing you are working on as you will see in future modules.






AutoCAD Self-paced Learning Modules - AutoCAD 2D - Revised 2007-04-11 9 - 9

Lab Exercise 9-1

Drawing Specifications

Time Allowed: 40 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 09-1 Module Template A4 Millimeters N/A N/A

Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.

Layering Scheme

Objects on Layer Name Color Linetype Lineweight

Construction Objects

All Objects

Instructions:

Construction

Object

253

Red

1. Setup the layers using the Layering Scheme above.2. Draw all construction objects on layer Construction

and freeze it when complete.3. Draw the object shown below.

4. Set the Viewres to 5000.5. Regenerate your drawing.6. Check your drawing with the key.Note: Do not use a calculator to complete this labexercise or any other lab exercise in the AutoCADModules. By using geometry principles and techniques,

Detail of Circle D

object snapping and construction objects, AutoCAD will do all the math for you.

Controlling the Drawing The CAD Guys Ltd. Copyright © 1993 - 2007

CompletedDrawing

Module 9







Construction Techniques

The following steps are the construction technique suggested by the author to help you learn how to

construct objects using AutoCAD. It is only the suggested method and if you can complete the drawingaccurately using a different construct technique, that is what is important. You may want to compare your construction technique with the authors.

Construction Hints

Do your best to complete the lab exercise drawing without

using the following hint(s). If you get stuck and can't completeit on your own, use the following hint(s) to help you.

Hint 1


Figure Hint 1






Hint 2

Hint 3

Hint 4


Figure Hint 2

Construction lines for circle D.

To draw circle D.

Figure Hint 3

Figure Hint 4

9 - 11








Lab Exercise 9-2

Drawing Specifications

Time Allowed: 40 Min.

Name Template Units Text Style Font

AutoCAD 2D Lab 09-2 Module Template A Inches N/A N/A

Note: Color, Linetype, and Lineweight are all < ByLayer < unless otherwise instructed.

Layering Scheme

Objects on Layer Name Color Linetype Lineweight


All Objects

Instructions:

Construction

Object

253

Red

1. Setup the layers using the Layering Scheme above.2. Draw all construction objects on layer Construction and freeze it when complete.3. Set the Viewres to 10000.4. Draw the object shown below.

5. Regenerate your drawing.6. Check your drawing with the key.Note: Do not use a calculator to complete this lab exercise or any other lab exercise in the AutoCADModules. By using geometry principles and techniques, object snapping and construction objects,AutoCAD will do all the math for you.







Construction Techniques

The following steps are the construction technique suggested by the author to help you learn how to

9 - 13

construct objects using AutoCAD. It is only the suggested method and if you can complete the drawingaccurately using a different construct technique, that is what is important. You may want to compare your construction technique with the authors.

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

Step 1 - Draw two construction lines from end of arc to end of arc as

shown to the right. Draw a circle at the midpoint of each line. Draw aconstruction arc from center of the circle to the center of the circle asshown in Step 1. Draw the small circle at the midpoint of the construction

arc.

Step 2 - Delete the construction arc you drew in Step 1. Draw a new construction arc from

center of small circle to center of small circle as shown in Step 2. Insert a circle at the midpoint

of the arc. You will have to do the same thing on the other side also.

Step 3 - Erase the construction arcs you drew in Step 2. Draw a construction arc from the

center of the small circle to the center of the small circle as shown in Step 3. Draw a circle atthe midpoint of the arc. You will have to repeat this three more times.

Figure Hint 1







9 - 14

Hint 2


Step 4 - After you insert the two construction lines at the ends of the arcs as

shown to the right. Draw a construction line from the midpoint of line to midpoint of line as shown in Step 1. Draw a circle at the midpoint of the line.

Step 5 - Erase the construction line that you drew in Step 4. Draw a new

construction line from the quad fo the circle to the midpoint of the line. It isimportant to draw from the quad to the midpoint. See Figure Hint 2B. Insert acircle at the midpoint of the line.

Step 6 - Erase the construction line you drew in Step 5 Draw in two more

construction lines and circles as the midpoints as shown in Figure Hint 2B.

Figure Hint 2A

Figure Hint 2B




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