Creating Symbols For Multiple Use -...

Creating Symbols/Blocks 1

Creating Symbols For Multiple Use

Engineering Design TechnologySacramento City College

2 Creating Symbols/Blocks

ObjectivesCreate and save blocks Insert blocks in drawingsEdit a block and update it in a drawing. Insert drawings and blocks into drawings.Create blocks that are saved independent of

the drawing.Construct and use a symbol library of blocks.


Symbols or “BLOCKS”


Constructing BlocksA block can be anyShape.Symbol.View.DrawingTextGroup of lines.

that you use more than once.


Constructing BlocksExamples of blocksChairDeskPlumbing FixturePiping Symbol.Etc.


Constructing BlocksWhen preparing drawingsLOOK for items that should be a block

Review the drawing.Look for any shapes, components, notes, and

assemblies that are used more than once.

These can be drawn once and then saved as blocks and re-used over and over again.Saves time.Saves $$$ for your company.


SymbolsAutoCAD has two commands for blocks.BlockWBlock


SymbolsBLOCK –Creates a block that is stored within the

CURRENT drawing ONLY.

Re-use block over and over in THAT drawing.LOCAL access only.


SymbolsWBLOCK –Creates a block that is saved as a separate

drawing file on your diskette, flash or hard drive

Can be used in any drawing.Put Blocks in Library on file server.Can be used by the entire company.GLOBAL access


Creating Symbols as BlocksBoth types of blocks can be scaled and rotated

to meet the drawing requirements.


SymbolsBoth types of blocks can be used to create a

symbol library.

A symbol library is a related group of symbols.PipeFurnitureMechanical symbols


Creating a Block


Creating a BlockProcedure to create a block.1. Select the drawing components that should

be part of the block.

2. Name the block.

3. Indicate the block “handle” or Insertion Point.


The Effect of Layers On Blocks


Drawing the Block ComponentsTwo Methods1. Draw blocks on Layer 02. Draw blocks with components on other

layers.


Drawing the Block ComponentsMethod 1 – Created on Layer 0The block will have the same color, linetype

and lineweight as the layer on which it is inserted.

The block will become “part of the family” where it is inserted.

Always create blocks on layer 0.

Usually the preferred method!


Drawing the Block ComponentsExample 1: If a block is Created on Layer “0” and the INSERT’ed on a layer with these attributes:

RED colorHIDDEN linetype

The block will appear RED and HIDDEN.


Drawing the Block ComponentsExample 2: If a block is Created on Layer “0” and the INSERT’ed on a layer with these attributes:

GREEN colorCENTER linetype

The block will appear GREEN and CENTER.


Drawing the Block ComponentsExample 3The block components will always have specific

color, linetype or lineweight regardless of which layer it is inserted on

OVERRIDE the ColorLinetype

Of the block entities BEFORE creating the block.


Layers and BlocksBlocks when created retain the properties of the layers on which they

were created.Retain the layers on which they were created.


Layers and BlocksByLayer is the default creation mode.When set to “ByLayer”, the block will take on

the properties of the layer it is inserted.

Block color and linetype are determined by the layer on which they were created.


Layers and Blocks If a block named circle was created with Red color.Dashed linetype.

When inserted or used on the drawing, it remains red and dashed, no matter what layer it is inserted on.


Layers and BlocksA block defined in ByLayer mode retains its

properties, including layer.

If the layers do not exist in the drawing where the block is being inserted, AutoCAD creates these layers.


Layers and BlocksA block must be created on layer 0 to assume

the properties of the layer it is inserted on.


Layers and Blocks If a block is created on layer 0, and inserted on

layer 1, it becomes part of Layer 1 and assumes Layer 1 properties.

If the block is exploded, the objects return back to layer 0 and to the original color and linetype of Layer 0.


ByLayer vs ByBlock If the current linetype is set to BYLAYER,The block is created with the current linetype

assigned to that layer.


ByLayer vs ByBlock If the current linetype is set to BYBLOCK, The block will assume the current color and

linetype when it is inserted into a drawing.


ByLayer vs ByBlock If the current linetype is set to BYBLOCK, Objects are created using the CONTINOUS

linetype until the objects are grouped into a block.

When the block is inserted into the drawing, those objects acquire the current linetype setting.


ByLayer vs ByBlock If the current color is set to BYLAYER,Objects are created with the color assigned to

the current layer.

If the current color is set to BYBLOCKObjects are created using color 7 (white or

black) until the objects are grouped into a block.

When the block is inserted into the drawing, it acquires the current color setting.


Changing Block Properties


Changing Block PropertiesUse the Properties window to change the

properties of a block.

To open the Properties windowRight-click, choose Properties

OrDouble-click entity.



Forcing Color/Linetypes for Blocks


Drawing the Block ComponentsOccasionally you will need to create a block

with Specific colors.Specific linetypes.

A BLOCK can be created with specific colors and linetypes regardless of the layer it is to be used on.


Drawing the Block ComponentsA user can override the colorlinetype settings

before drawing the objectsUse OBJECT PROPERTIES drop-down box.


Drawing the Block ComponentsTo allow the block to assume the current color

and linetype when the block is inserted into a drawing, set the current object color and linetype to ByBlock.


Drawing the Block ComponentsTo set the color to ByBlock, Pick ByBlock in the Color Control drop-down

list of the Object Properties toolbar.OR

Pick Color... from the Format pull-down menuto access the Select Color dialog box. OR

Pick the ByBlock button in the Logical Colors area.


Drawing the Block ComponentsTo set the linetype to ByBlock, Pick ByBlock in the Linetype Control drop-down

list of the Object Properties toolbar.OR

Pick Linetype... from the Format pull-down menu to display the Linetype Manager dialog box. OR

Pick ByBIock in the Linetype list and then pick the Current button.





Drawing the Block ComponentsA block created with ByBlock settings assumes

the current color and linetype when it is inserted into a drawing, regardless of the current layer setting.


Creating Blocks


To Create A BlockTo create a BLOCK:Pick the Make Block button in the Draw toolbar

ORPick Make... from the Block cascading menu in

the Draw pull-down menuOR

Enter B, BLOCK, or BMAKE at the Command: prompt.

Any one of these methods displays the Block Definition dialog box.



To Create A Block1. In the Name: text box, enter a name for the

block, such as BORDER. The name cannot exceed 255 characters.It can include numbers, letters, and spaces, as

well as the dollar sign ($), hyphen (-), and underscore (-).




To Create A Block2. In the Objects area, pick the Select objects

buttonUse your pointing device to select objects for

the block definition.

Select all the objects that will make up the block. Press [Enter] when you are done.




To Create A BlockThe Block Definition dialog box reopens,The number of objects selected is shown in the

Objects area.


To Create A Block3. In the Objects area specifyRetainConvertDelete




To Create A BlockRetainKeep the selected objects in the current

drawing (in their original state).Makes a copy of the objects glued together as

a BLOCK in Memory.


To Create A BlockConvert to Block (default)Replaces the selected objects with one of the

blocks you are creating.Makes a copy of the objects glued together as

a BLOCK in Memory.

DeleteRemove the selected objects after the block is

defined.Makes a copy of the objects glued together as

a BLOCK in Memory.


To Create A BlockAll threeCause a BLOCK to be created in memory.

The only difference iswhat happens to the ORIGINAL objects.

They areRetainedConvertedDeleted




To Create A Block4. In the Base point area:Enter the coordinates for the insertion base

point OR

Pick the Pick point button to use your pointing device to select an insertion point.






To Create A Block5. In the Description: text boxEnter a textual description to help identify the

block for easy reference, such as “Vacuum pump symbol”.




To Create A Block6. In the Preview icon areaSpecify whether to create an icon from the

BLOCK definition. The icon is used to provide a preview image

when using the AutoCAD DesignCenter. You can have an icon for every block if you

wish.


To Create A Block6. In the Preview icon areaTo omit an icon from the block definition, pick

the Do not include an icon radio button. To save an icon with the block definition, pick

the Create icon from block geometry radio button.

An image of the icon is then displayed to the right.




To Create A Block7. Use the Insert units: drop-down list to Specify the type of units the AutoCAD Design

Center will use when inserting the block.

8. After you have finished defining the block, pick OK.




Verifying Block Was Created


To Create A BlockTo verify that the block was saved properly:Access the Block Definition dialog box.Pick the Name: drop-down list button to display

a list of all blocks in the current drawing, Figure 23-5.

The block names are organized in numericaland alphabetical order.





The EXPLODE Command


The EXPLODE CommandThe EXPLODE command breaks apart any:Existing blockPolylineDimension.


The EXPLODE CommandTo access this commandPick the Explode button in the Modify toolbar

ORSelect Explode from the Modify pull-down

menuOR

Type X or EXPLODE at the Command:prompt:


The EXPLODE CommandWhen the block is exploded, the individual

objects can now be changed individually.


The EXPLODE CommandNOTE You can explode a block that was

scaled using different X, Y, and Z values when it was inserted.

This type of block is technically a nonuniformly scaled block.

Versions of AutoCAD prior to Release 13 did not allow exploding of such blocks (!)


The PURGE Command


Storing a Drawing As A WBlockThe PURGE command can also be used to

remove any unusedLayersLinetypesText stylesDimension stylesMultiline stylesBlocks


Inserting A Block


Inserting A BlockOnce a block has been created, it is easy to

insert it into a drawing.

Determine a proper size.Determine a rotation angle.Determine the proper layer.


Inserting A BlockUse the INSERT command by:Type I, INSERT, or DDINSERT at the

Command: promptOR

Pick the Insert Block button from the Draw toolbarOR

Pick Block... from the Insert pull-down menu.


Inserting A BlockSelect the block you wish to insert From the drop-down list

OR Enter the block name in the Name: text box.



Inserting A BlockPick the Name: drop-down list button to access

the defined blocks in the current drawing.

Highlight the name of the block you wish to insert.







Inserting A BlockSpecify the Insertion Point

Specify the Scale.

Specify the Rotation angle.



Inserting A BlockSpecify the check box whether to EXPLODE the

block upon inserting it.

EXPLODE breaks block apart into its components.




Inserting A Block Insertion point area.Use the Specify On-screen check box to pick

an insertion point on screen and insert the block dynamically.




Inserting A BlockTo insert the block using absolute coordinatesDisable the Specify On-screen check box Enter the coordinates in the X:, Y:, and Z: text

boxes. If X, Y, Z are used, the block is immediately

inserted at the specified coordinates when you pick OK.


Inserting A BlockTitle Blocks often use 0,0,0 as the Insertion

Point.

Most other blocksChairsDesksPiping symbolsEtc

do NOT use 0,0,0 as the Insertion Point.






Inserting A BlockScale area.The Scale area allows you to specify scale

values for the block in relation to the X, Y, and Z axes.

The Specify On-screen check box is inactive by default.

This causes the block to be inserted at a one-to-one scale once the insertion point has been selected.




Inserting A BlockScale area.

Specify On-screen - prompts you to enter the scale at the command line when inserting the block.

Enter scale valuesX.Y.Z.



Inserting A BlockScale area - Uniform Scale check box

Scales object uniformly in all directions.

This is the most common setting.




Inserting A BlockRotation area.Use to insert the block at a specified angle.The default angle is zero. Enter a different value in the Angle: text box. Activate the Specify On-screen check box to be

prompted for the rotation angle at the command line when inserting the block.





Inserting A BlockExplode check box.When a block is created, it is saved as a single

object. It is defined as a single object when inserted in

the drawing, no matter how many objects were used to create the block.


Inserting A BlockExplode check box.Causes the BLOCK to explode into its original

objects for editing purposes.

If you explode the block upon insertion, it will assume its original properties, such as

Original layerOriginal colorOriginal linetype.



Inserting A Block If you are specifying the insertion point on-

screen, the following prompt appears: Specify insertion point or

[Scale/X/Y/Z/Rotate/PScale/PX/PY/PZ/PRotate]: (pick the point to insert the block)


Inserting A BlockScale.Y. Z. Rotate.PScale.PX.PY. PZ. PRotate.


Inserting A BlockScale.Affects the overall scale of the X, Y, and Z

axes.Entering a NEGATIVE scale factor INSERT’s a

a mirror image of a block.


Inserting A BlockX.Affects only the X scale factor.

Y.Affects only the Y scale factor.

Z.Affects only the Z scale factor.


Inserting A BlockRotate.Sets the rotation angle.

PScale.Preview the scale of the X, Y, and Z axes. You are then prompted to enter the actual scale

factors.


Inserting A BlockPreview ScalePX.

Preview the scale of the X axis, then enter the actual scale factor.

PY.Preview the scale of the Y axis, then enter the actual

scale factor.PZ.

Preview the scale of the Z axis, then enter the scale factor.


Inserting A BlockPreview RotatePRotate.Preview the rotation angle, then enter the

actual rotation angle.


Inserting A Block If you are specifying the scale factor, the

following prompt appears:Enter X scale factor, specify opposite corner, or

[Corner/XYZI <1 >: (pick a point, or enter a value for the scale).


Inserting A BlockMoving the cursor scales the block dynamically

as it is dragged.


Inserting A Block If you enter an X scale factor or press [Enter] to

accept the default scale value, the prompt reads:Enter Y scale factor <use X scale factor>:

(enter a value or press [Enter] to accept the same scale specified for the X axis)

Specify rotation angle <0>: (pick a point, enter a value for the rotation angle and press [Enter], or press [Enter] to accept the default angle)


Inserting A BlockThe prompt for the Y scale factor allows you to

accept the X scale factor for Y by simply pressing [Enter].


Inserting Multiple CopiesOf A Block


Inserting Multiple CopiesUse the MINSERT command to insert multiple

copies of a block.

MINSERT combines INSERT and ARRAY into one command.


Inserting Entire Drawings


Inserting Entire DrawingsUse INSERT to insert an entire drawing file into

the current drawing.

Example:Titleblock


Inserting Entire DrawingsWhen one drawing is inserted into another, the

inserted drawing becomes a block reference.

It does not inherit the color, linetype or thickness properties of the layer it is inserted on.

You can explode the inserted drawing back to its original objects (and original layers).


Inserting Entire DrawingsA drawing that is inserted brings any existing Block definitions.Layers.Linetypes.Text stylesDimension styles.

into the current drawing.


Inserting Entire DrawingsThe default insertion point of every drawing is

0,0,0.Use the BASE command to change the

insertion point of a block.Pick Base from the Block cascading menu in

the Draw pull-down menuOR

Type BASE at the Command: prompt.


Creating a Block From A Drawing File


Creating a Drawing File Block You can create a block from any existing

drawing.You can name your new block anything you

wish.

Remember, if something has already been drawn, try to use it as a block rather than redrawing it.


Creating a Drawing File Block Example: Use the -INSERT command to define

a block named BOLT from an existing drawing file named fastener.dwg:Command: -INSERTEnter block name or [?]: <current>:

BOLT=FASTENER.Specify insertion point or

[Scale/X/Y/Z/Rotate/PScale/PX/PY/PZ/PRotate]:

(press the [Esc] key) to CANCEL the command.


Creating a Drawing File Block The drawing is not inserted on screen because

the command was canceled (the ESC key).

However, a block named BOLT is saved and added to the drawing file (!)

It can be used in the same manner as any other block.


Creating Permanent Global BlocksThe WBLOCK Command


Creating a Drawing File Block Blocks created with the BLOCK command can

only be used in the drawing in which they were made.

You may want to use blocks on many different drawings without having to redraw them.


Creating a Drawing File Block Use the WBLOCK (write block) command to

create a drawing (.dwg) file out of a block OR a drawing.


Creating a Drawing File Block Use the WBLOCK command to create a global

block from any object

It does not have to be first saved as a block.

The resulting drawing file can then be inserted as a block into any drawing.


Creating a New WBlock You can create a WBLOCK from a shape you

have just drawn, but you have not yet made a block.

(The TITLEBLOCK assignment).

Enter the WBLOCK command.Select the Objects option button.Pick the Select objects button to select the

objects for the drawing file.


Creating a New WBlock Pick the Pick point button to select the insertion

point.Enter coordinates in the X:, Y:, and Z: text

boxes.Give the file a name in the File name: text box.


Creating a New WBlock Select the type of units.

Pick OK.


Creating a New WBlock This is the same sequence that is used with the

BLOCK commnand.

However, the WBLOCK is saved to disk as a drawing file, not as a block in the current drawing.


Storing a Drawing As A WBlock


Storing a Drawing As A WBlockAn entire drawing can also be stored as a

WBLOCK.

Pick the Entire drawing option button in the Write Block dialog box.

Give the WBLOCK a name in the File name, text box.

Specify a location for the new drawing file


Storing a Drawing As A WBlockSelect the type of units

Pick OK when you are through.


Storing a Drawing As A WBlockThe whole drawing is saved to disk as if you had

used the SAVE command.

All unused blocks are deleted from the drawing.

If the drawing contains any unused blocks, this method reduces the size of a drawing considerably.


Storing a Drawing As A WBlockThe Entire drawing WBLOCK option Acts like PURGERemoves named objects that are unused Reduces your drawing file size.

Quick way to clean up (PURGE) drawingRemoves unused

BlocksLayersStylesObjects.


Block Insertion Options


Block Insertion OptionsUse the Corner option to get an approximate

dynamic scaling technique.

If the DRAGMODE system variable is set to Auto, you can size the block dynamically as you move the cursor.


Block Insertion OptionsThe Corner option:Enter X scale factor, specify opposite corner, or

[Corner/XYZ] <1>: CSpecify opposite corner: (move the cursor to

change the size of the block and pick a point or enter absolute coordinates)

Pick a point on screen above and to the right of the insertion point to insert the block as drawn.


Block Insertion OptionsThe Corner option:Picking a corner point below or to the left of the

insertion point generates a mirror image.


Block Insertion OptionsA block that is scaled during insertion can be

classified asA real block.A schematic block.A unit block.


Block Insertion OptionsA real blockIs drawn at a one-to-one scale.Is inserted into the drawing using 1 for both the

X and Y scale factors.


Block Insertion OptionsA schematic blockIs a block that is originally drawn at a one-to-

one scale.Is inserted into the drawing using the scale

factor of the drawing for both the X and Y scale values.

Examples of schematic blocks NotesDetail bubblesSection symbols.


The -BLOCK Command


The -BLOCK CommandThe -BLOCK command can also be used to

create new blocks and list existing blocks.Access this command by:Typing -B or -BLOCK at the Command: prompt.


The -BLOCK CommandWhen the -BLOCK command is entered, the

options in the Block Definition dialog box are presented as prompts on the command line.


The -BLOCK CommandTo display a list of block names, use the ?

option:Command: -B or -BLOCKEnter block name or [?]: ?Enter block(s) to list <*>:

Press [Enter] to list all of the blocks in the current drawing.


The -BLOCK CommandThis listing showsEach block nameThe different types of blocks The number of each type in the drawing.


The -BLOCK CommandWhen you create a block, you have actually

created a block definition.

The first entry in the block listing is that of defined blocks.


The -BLOCK CommandUser blocks are those created by the user.

External references are drawings referenced with the XREF command.


Nesting Blocks


Nesting BlocksBlocks can be used when creating other blocks.

This process is called nesting, where larger blocks contain smaller blocks.

The larger block must be given a different name.


Editing Blocks


Editing Blocks In-Place Editing allows you to make minor

changes to blocks, wblocks or drawings that have been inserted in the current drawing.

You can edit blocks without having to explodeand redefine them.

In-place editing cannot be used on blocks that have been inserted with MINSERT.


Editing BlocksUse the REFEDIT command to edit blocks in

place.Type REFEDIT at the Command: prompt.

ORUse the Refedit toolbar

ORPick In-place Xref and Block Edit and Edit

Reference in the Modify pull-down menu.




Editing BlocksThe REFEDIT command options:Reference namePreviewEnable unique layer and symbol namesDisplay attribute definitions for editingNextOK



Editing BlocksReference nameDisplays the name of the selected block and

any references nested within the selected block.

PreviewDisplays an image of the the selected block.Use the NEXT button to cycle through nested

blocks.


Editing BlocksEnable unique layer and symbol namesControls layer and symbol names of objects

extracted from the referenceIf checked, layer and symbol names are given

a prefix such as $#$


Editing BlocksDisplay attribute definitions for editingIf checked, the block attributes and attribute

definitions are available for editing.Edited attribute definitions only take effect in

future insertions of the edited block.NextUse to cycle through nested blocks.

OKPick OK after selecting the desired block.


Editing BlocksAfter you pick the OK button, the Refedit

toolbar is displayed and you get the following prompt:

Select nested objects: (select the objects in the block to edit)




Editing BlocksPick all objects in the block to be edited, then

press [Enter].Select nested objects:

Use REFCLOSE or the Refedit toolbar to endreference editing session.

Command:












Editing Blocks If multiple insertions of the same block are

displayed, pick the one you originally selected.


Editing BlocksWhen the Command: prompt is available, all

the objects in the drawing are grayed out, except the objects you selected.

Use any drawing or editing commands to alter the object as desired.


Editing BlocksPick the Save back changes to reference button

in the Refedit toolbar. Pick OK to continue with the save.Changes to the edited block are displayed

immediately.Changes affectother insertions of the same block and future insertions of the block.


Editing BlocksObjects selected for editing are referred to as

the “working set” and appear brighter than other objects.

Objects that are not a part of the working set are faded.


Editing BlocksThe percent of fading is controlled in the

Display tab of the Options dialog box.A maximum of 90% fading is allowed, and the

default is 50%.


Editing BlocksThis value is controlled by the XFADECTL

variable.Enter a value in the Reference Edit fading

intensity text box in the lower-right comer, or move the slider.



Editing BlocksObjects that are added to the drawing during

the edit can be removed from the working set.


Editing BlocksThe Refedit Toolbar Buttons.Add objects to working set.Remove objects from the working set.Discard changes to reference.Save changes back to block.


Editing BlocksAdd objects to working set.Any object that is drawn during the in-place edit

is automatically added to the working set.Use this button to add additional existing

objects. If an object is added to the working set, it is

removed from the host drawing.


Editing BlocksThe REFSET command allows you to add to or

remove objects from the working set.


“Checking Out” a Reference A drawing must be checked out to edit it. If the

REFEDIT command is issued, when the block is not checked out, an error message will result.

Command: REFSET** Command not allowed unless a reference is

checked out with REFEDIT command **.


Editing BlocksRemove objects from the working set.Use this button to remove objects from the

working set.When an object is removed from the set it

appears faded.If an object is removed from the working set, it

is added to the host drawing.


Editing BlocksDiscard changes to reference.Pick to exit the reference edit function without

saving changes to the object.

The REFCLOSE command allows you to save or discard changes to the working set, and closes reference editing.


Editing BlocksThe REFEDIT command can also be used in the

command window. Command: -REFEDITSelect reference: (select the block to change)Select [Enter] (to accept the currently

highlighted reference)OR

Press [Enter] to use the Next option:


Editing BlocksSelect nesting level [Ok/Next] <Next>: [Enter]Select nesting level [Ok/Next] <Next>: O [Enter]Select nested objects: (select objects within the

block to edit)Display attribute definitions [Yes/No] <No>:

(type Y or [Enter] for No)Use REFCLOSE or the Refedit toolbar to end

reference editing session.Command: (use drawing and editing

commands as needed to edit the block)


Editing BlocksUse the Save back changes to reference button

on the Refedit toolbarOR

Type the REFCLOSE command and use one of its options.


Editing BlocksThe Save option :Command: REFCLOSE [Eenter]Enter option [Save/Discard reference changes]

<Save>: [Enter]The AutoCAD alert box is displayed.Use OK to accept the changes.


Redefining Existing Blocks


Redefining Existing BlocksTo redefine an existing block:1. Insert the block to be redefined anywhere in

your drawing.2. Make sure that you know where the

insertion point of the block is located.3. Explode the inserted block using the

EXPLODE command.4. Edit the block as needed.


Redefining Existing Blocks5. Recreate the block definition using the

BLOCK command.6. Give the block the same name and the same

insertion point it originally had.7. Select the objects to be included in the

block.8. Pick OK.When a message from AutoCAD appears and

asks if you want to redefine the block, pick Yes.


Redefining Existing Blocks9. When the BLOCK command is complete, all

insertions of the block are updated.


Redefining Existing BlocksA common mistake is to forget to use the

EXPLODE command before redefining the block.

When you try to create the block again with the same name, an alert box indicating the block references itself is displayed.

This means you are trying to create a block that already exists.


Redefining Existing BlocksOnce you press the OK button, the alert box

disappears and the Block Definition dialog box is redisplayed.

Press the Cancel button, explode the block to be redefined, and try again.


Redefining Existing BlocksYou can also redefine existing blocks using the -

BLOCK command:Insert the block Explode the blockMake necessary changes have been madeIssue the -BLOCK command.Enter the same block nameEnter Y or YES to redefine the blockPick the same insertion pointSelect the revised objects.Press [Enter]


The Circular Reference Error


The Circular Reference ErrorWhen you try to redefine a block that already

exists (using the same name), AutoCAD informs you that the block references itself.


The Circular Reference ErrorA block can be composed of any objects,

including other blocks. When using the BLOCK command, AutoCAD

makes a list of all the objects that compose the new block.

AutoCAD must refer to any existing block definitions that are selected to be part of the new block.


The Circular Reference Error If you select an instance, or reference, of the

block being redefined as a component object for the new definition, a problem occurs.

You are trying to redefine a block name using a previous version of the block with the same name.

In other words, the new block refers to a block of the same name, or references itself.


The Circular Reference ErrorExample #1 –Assume you create a block named BOX that is

composed of four line objects in the shape of a square, and insert it.

You then decide that the block needs to be changed so that it contains a small circle in the lower-left corner.

If the original BOX block is exploded, all that is left are the four line objects.


The Circular Reference ErrorAfter drawing the required circle, you can enter the

BLOCK command and recreate a block named BOX by selecting the four lines and the circle as the component objects.

Redefining a block destroys the old definition and creates a new one.


The Circular Reference ErrorExample #2 –assume you do not explode the block, but still draw

the circle and try to redefine the block.By selecting the BOX block and the circle, a new

block named BOX would now be a block reference of the BOX block with a circle.

The old block definition of BOX has not been destroyed, but a new definition has been attempted.


The Circular Reference ErrorThus, AutoCAD is trying to define a new block

named BOX by using an instance of the BOX block.

This is referred to as a circular reference, and is what is meant by a block referencing itself.


Inserting a Drawing File withSelect Drawing File

Dialog Box


Inserting a Drawing File The INSERT command can be used to:Insert a block Insert a wblock. Insert another drawing file.


Inserting a Drawing File Picking the Browse... button in the Insert dialog

box activates the Select Drawing File dialog box. (To insert a WBLOCK)

You can then scroll through the files in any folder, or on another drive, and pick the file name you need.


Inserting a Drawing File The -INSERT command can be used to insert

Wblocks also.To access the Select Drawing File dialog box,

enter a tilde (-) when prompted for the block name as follows:Command: -INSERTEnter block name or [?]: <current>: ~



Inserting a Drawing File You can use the tilde character (~) whenever

any AutoCAD command prompt requests a file name.

One of several dialog boxes is then displayed so that you may select a file.


Revising an Inserted Drawing


Revising an Inserted DrawingYou may find that you need to revise a drawing

file that has been used in other drawings. If this happens, you can quickly update any

drawing in which the revised drawing is used.


Revising an Inserted DrawingExample: a drawing file named “pump” was

used several times in a drawing.To update references to the changed “pump”

fileType -INSERT Type an equal sign (=) after the block name to

update all of the references to the pump drawing:


Revising an Inserted DrawingCommand: -INSERTEnter block name or [?]: <current>: PUMP=Block "pump" already exists. Redefine it?

[Yes/No] <N>: YiBlock "pump" redefinedRegenerating model.Specify insertion point or

[Scale/X/Y/Z/Rotate/PScale/PX/PY/PZ/PRotate]:

(press the [Esc] key)


Revising an Inserted DrawingAll of the pump references are automatically

updated.


Revising an Inserted DrawingExample #2: A drawing file named “fastener” was inserted

into your current drawingThe drawing file “fastener” was saved as a

block “screw”.

You have decided to revise the fastener drawing.


Revising an Inserted DrawingThe screw block can be updated using the -

INSERT command as follows:Command: -INSERTEnter block name or [?]: <current>:

SCREW=FASTENERBlock "screw" already exists. Redefine it?

[Yes/No] <N>: YiBlock "screw" redefinedRegenerating model.


Revising an Inserted Drawing If you work on projects in which inserted

drawings may be revised, it may be more productive to use reference drawings instead of inserted drawing files.

Reference drawings are used with the XREF command

This is covered in Chapter 24.


Revising an Inserted DrawingAll referenced drawings are automatically

updated when a drawing file that contains the externally referenced material is loaded into AutoCAD.


Creating Symbol Libraries


Creating Symbol LibrariesAs you become proficient with AutoCAD, you

will want to start constructing symbol libraries. A symbol library is a collection of related

shapes, views, and symbols that are used repeatedly in drawings.


Creating Symbol LibrariesSymbols are generally incorporated into your

screen and tablet menus.


Creating Symbol LibrariesFirst, you must decide where symbols (blocks

and drawing files) are stored and how they can be inserted into different drawings.


Creating Symbol LibrariesRemember:BLOCK a block is saved with the drawing WBLOCK saves the block as a separate

drawing file.


Creating Symbol LibrariesA complete drawing file occupies considerably

more disk space than a block. Also, a drawing file can contain many blocksOnce the drawing file is inserted into the

current drawing, all the blocks in the drawing file are also inserted into the drawing.


Creating Symbol LibrariesTo use blocks, each person in the office or class

must have a copy of the drawing that contains the blocks.

The blocks are usually created and stored in a template file or a separate drawing file.

If drawing files are used, each student or employee must have access to the files.


Creating Symbol LibrariesUsing 3.5" DiskettesGood to use for temporarily storing backup

copies of drawing and data files. Are NOT a good choice for the primary means

for storing symbols, especially if you have sufficient room on the hard disk, optical, or network server drives.

Inserting and removing diskettes from a disk drive is tedious and time-consuming

It takes more time for the computer to access the diskettes.


Creating Symbol LibrariesCreate all symbols as separate drawing files.Assign one person to initially create the

symbols for each specialty.Follow class or company symbol standards.Print a hard copy of the symbol library.


Creating Symbol Libraries Include A representation of the symbol, Symbol insertion pointAny other necessary informationSymbol location.Provide all users of the symbols with a copy of

the listing.


Creating Symbol LibrariesSave symbols by discipline:ElectronicElectricalPipingMechanicalStructuralArchitecturalLandscapingMapping


Creating Symbol LibrariesThe Hard Disk DriveIs the best places to store a symbol library.Is easily accessedIs quickIs more convenient to use than diskettes.


Creating Symbol LibrariesCreate symbols with the WBLOCK command.Create directories for each discipline.Save discipline specific symbols in the same

directory.


Creating Symbol LibrariesFolder structure:BlocksArch CivilElectLandscapeMechStruct


Creating Symbol Libraries If a symbol is saved as a file, you must search for its folder the first time the

symbol is inserted. After its initial insertion, the drawing file is

saved as a block definition in the current drawing, and it can be accessed by entering its file name.


Creating Symbol LibrariesAll workstations in the class or office should

have folders with the same names.One person should be assigned to update and

copy symbol libraries to all workstation hard drives.

Drawing files should be copied onto each workstation's hard drive from a master diskette or network server.


Copying a Symbol Library into a New Drawing


Copying a Symbol Library A symbol library of blocks that is part of a

drawing can be copied into a new drawing file.The incoming blocks are not displayed, they are

only included as definitions in the drawing file.


Copying a Symbol Library This allows you to use blocks created on one

drawing without also having to use the drawing.


Copying a Symbol Library Example: If the drawing pipeflow.dwg saved on

the diskette in the A: drive contains the needed blocks, use the -INSERT command as follows:Command: -INSERTEnter block name or [?] <current>:

A:PIPEFLOWSpecify insertion point or

[Scale/XN/Z/Rotate/PScale/PX/PY/PZ/PRotatel:(press the [Esc] key to cancel the command)


Copying a Symbol Library After pressing the [Escl key:The drawing is not inserted on screenBut, the blocks are now included with the new

file.


Copying a Symbol Library NOTE: If a symbol library is saved as a template file, it

cannot be inserted into another drawing.


Copying a Symbol Library A symbol library template is beneficial when

starting a new drawing in which the symbols are to be used.

For example, when starting a new mechanical drawing, a mechanical template that contains a mechanical symbol library would be helpful.


Renaming Blocks


Creating a Symbol Library ListingBlocks can be renamed using the RENAME

command.Access this command by Selecting Rename... from the Format pull-down

menu OR

Entering REN or RENAME at the Command: prompt.



Creating a Symbol Library ListingNOTE Since AutoCAD does not permit the

renaming of layer 0 or the Continuous linetype, these two named objects do not appear in the Items list in the Rename dialog box.


Creating a Symbol Library ListingNOTE The -RENAME command can be used

to rename blocks, layers, views, and other named objects at the Command: prompt.


Deleting Named Objects


Deleting Named ObjectsA block is a named object. In many drawing sessions, not all of the named

objects in a drawing are used.These objects occupy disk space. It is good practice to delete or purge the

unused objects with the PURGE command.


The PURGE Command


Deleting Named ObjectsTo access the PURGE command:Pick Purge from the Drawing Utilities cascading

menu in the File pull-down menu, OR

enter PU or PURGE at the Command: prompt.


Deleting Named ObjectsThe command sequence displays each of the

unused named objects one at a time.Decide whether to delete or save them.

You can also specify a named object by entering the option corresponding to the type of object to be purged.


Deleting Named ObjectsUse the PURGE command in the following

manner to delete a block named LINESPEC:Command: PU or PURGEEnter type of unused objects to purge[Blocks/Dimstyles/LAyers/LTypes/Plotstyles/SH

apes/textSTyles/Mlinestyles/All]: BEnter name(s) to purge <*>: Verify each name to be purged? [Yes/No] <Y>:Purge block "linespec"? <N> Y


Deleting Named ObjectsThe PURGE command Lists all unused blocks individually Gives you the option to answer yes or no.

The All option can be used to delete all unused named objects.


Deleting Named ObjectsThe PURGE command Is a good way to clean up a drawing after it is

completed.Is slower than using the Entire drawing wblock

option in the Write Block dialog box.

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