Objectives At the end of this c hapter, you should be able to:
Locate and invoke the Modify command Erase objec ts from the drawing.
Move objects from a base point to a second point of a displac ement.
Rotate objec ts about a basepoint.
Enlarge or reduc e objec ts with sc ale.
Make mirror images of selected objects.
Make rec tangular and polar arrays of existing objec ts Stretc h selec ted objec t.
Trim away parts of objec ts at c utting edges.
Extend objects to selected boundary edges.
Create a fillet between two objec ts.
Create a Chamfer between two objec ts.
Create parallel c opies of objec ts with offset.
INTRODUCTION
Draw commands are used to create new objects. Modify commands or edit c ommands are used to c hange existing objec ts or to use existing objec ts to c reate new and similar objec ts. The c ommands listed below are c overed in this unit:
Erase
Move
Rotate
Trim
Sc ale
Mirror
Array
Stretch
Extend
Fillet
Chamfer
Offset
Divide
Measure
Change
Pedit
ERASE
The erase command deletes the objects you select from the drawing. Any of the object selec tion methods c an be used to highlight the objec t to erase. The only other required ac tion is press Enter to c ause the erase to take effec t.
Methods for invoking the ERASE command include:
Toolbar :
Pull-down Menu : Modify > Erase
Command : Erase
An example of the erase command prompt is as follows:
Command: Erase
Selec t Objec ts: PICK (Use any object selection method.)
Selec t Objec ts: PICK (Continue to selec t desired objec ts)
Selec t objec ts: Enter (Confirm the objec t selec tion proc ess and c auses Erase to take effect. )
Command:
If objects are erased ac c identally, U or Undo c ommand c an be used immediately following the mistake to undo one step, or oops c an be used to bring bac k into the drawing whatever was erased the last time erase was used.
MOVE
Move allows you to relocate one or more objec ts from the existing position in the drawing to any other position you spec ify. After selec ting the objec ts to move, you must spec ify the base point and sec ond point of displac ement.
Methods for invoking the MOVE command include:
Toolbar :
Pull-down menu : Modify > Move
Command : Move
The prompts for the MOVE command are as follows:
Command: move
Selec t objec ts: ( Selec t objec ts you want to move ) Selec t objec ts: ( Press ENTER )
Base point or displac ement: ( Selec t a point )
Second point of displac ement: ( Selec t a point )
Example
In the following figure, you want to put a c orner of the rec tangle at the c enter of the circle.
Command: move
Selec t objec ts: 1 found ( selec t the rec tangle ) Selec t objec ts: ( Press ENTER )
Base point or displac ement: end of ( Selec t the c orner of the rec tangle )
Second point of displacement: center of ( Select any point on the circle c irc umferenc e )
ROTATE
Selec ted objec t c an be rotated to any position with this c ommand. After selec ting objec t to rotate, you selec t a “basepoint” ( a point to rotate about ) then spec ify an angle for rotation.
Methods for invoking the ROTATE command include:
Toolbar :
Pull-down menu : Modify>rotate
Command : Rotate
An example of the ROTATE command prompt is as follows:
Command: rotate
Selec t Objec t: ( Spec ify the objec ts to rotate )
Base Point : end of ( Spec ify the basepoint ) < Rotation angle>/Referenc e:
Figure 2: Using the ROTATE command to rotate the rectangle about 900 from basepoint
TRIM
The Trim c ommand allows you to trim ( shorten ) the end of end objec t bac k to the intersec tion of another objec t ( figure ). The middle sec tion of an objec t c an also be trimmed between two intersec tion objec ts. There are two steps to this command;
1. PICK one or more “cutting edge” ( existing object )
2. Then PICK the objec t or objec ts to trim ( portion to remove )
The c utting edges are highlighted after selec tion. Cutting edges themselves can be trimmed if they intersec t with other c utting edges, but lose their highlight when trimmed.
Methods for invoking the TRIM command include:
Toolbar :
Pull-down menu : MODIFY > TRIM
Command : TRIM
An example of the erase c ommand prompt is as follows:
Command: trim
Selec t c utting edges: ( Projmode = UCS, Edgemode = No Extend) Selec t Objec ts: PICK ( Selec t an objec t to use as a c utting edge )
Selec t Objec ts: PICK
Selec t Objec ts: Enter
< Selec t objec t to trim >/Projec t/Edge/Undo:PICK ( selec t the end of and objec t to trim )
< Selec t objec t to trim >/Projec t/Edge/Undo: PICK
< Selec t objec t to trim >/Projec t/Edge/Undo:Enter
Command:
SCALE
The scale command is used to increase or dec rease the size of objec ts in a drawing. The scale command does not normally have any relation to plotting a drawing to scale.
Methods for invoking the SCALE command include:
Toolbar :
Pull-down menu : MODIFY > SCALE
Command : SCALE
An example of the sc ale c ommand prompt is as follows:
Command : scale
Selec t Objec t : PICK or ( coordinates) ( Selec t the objec t to sc ale )
Selec t Objec t : ENTER ( Indicates completion of the object selection ) Base point : PICK or ( coordinates ) ( Selec t the stationary point)
Scale factor <Reference>: PICK or (value) or (coordinates) ( Enter a value for the sc ale fac tor or interac tively sc ale the set of objec t)
Command :
Figure 7 : Using SCALE Command to enlarge the rec tangle with sc ale fac tor;2
MIRROR
This command creates a mirror image of selected existing objects. You can retain or delete the original objec ts ( ‘old objec t’ ). After selec ting objec ts, you c reate two points spec ifying a ‘rubberband line’, or ‘mirror line’, about whic h to mirror.
Methods for invoking the MIRROR command include:
Toolbar :
Pull-down menu : MODIFY > MIRROR
Command : MIRROR
An example of the sc ale c ommand prompt is as follows:
Command : mirror
Selec t Objec t : PICK ( Select object or group of object to mirror )
Selec t Objec t : Enter ( Press Enter to indic ate c ompletion of objec t selec tion. )
First point of mirror line : PICK or (coordinates) (Draw first endpoint of line to represent mirror axis by PICKing or entering coordinates)
Second point of mirror : PICK or (coordinates) (Draw second point of line by PICKing or entering coordinates)
Delete old objec ts ? <N> Enter or Y ( Press Enter to yield both sets of objec ts or enter Y to keep only the mirrored set.)
Command :
ARRAY
The array command c reates either a Rec tangular or Polar ( c irc ular ) pattern of existing objec t that you selec t. The pattern c ould be c reated from a single or from a group of objects. Array copies a duplicate set of objects for each ‘item’ in the array.
Methods for invoking the ARRAY command include:
Toolbar :
Pull-down menu : MODIFY > ARRAY
Command : Array
Rectangular
This option c reates an Array of the selec tion set in a pattern c omposed of rows and c olumns. The c ommand syntax for a rec tangular is given next:
Command : Array
Selec t Objec ts : PICK ( Selec t objec t to be arrayed )
Selec t Objec ts : Enter ( Indicates completion of object selection) Rec tangular or Polar array (<R>/P) : R (indic ates rec tangular )
Number of rows (---)<1> : (value) ( enter value for number of rows) Number of c olumns (lll)<1> : (value) (enter value for number of c olumns)
Unit c ell or distanc e between rows (---): ( value) ( enter a value for the distanc e from any of one objec t to the same point on an objec t in the
adjac ent row.
Distanc e between c olumns (lll) : (value ) (enter a value for the distance from any point on one objec t to the same point on an objec t in the adjac ent column.
Polar
This option c reates a c irc ular pattern of the selection set with any number of copies or ‘items’. The number of item specified includes the original selection set. You also spec ify the c enter of the array, angle to generate the array through and orientation of ‘item’.
Command : Array
Selec t Objec t : PICK ( selec t objec t to be arrayed)
Selec t Objec t : Enter
Rec tangular or Polar array ( <R>/P ) : P (indic ates Polar array)
Center point of array : PICK ( selec t point from array to be generated around)
Number of items : ( value ) ( enter value for number of copies including original selection set )
Angle to fill (+=c c w,-=cw) <360>: Enter or (value) (press enter for full c irc ular array, enter value for less than 360 degree array; enter negative value for c loc kwise generation array)
Rotate objec t as they are c opied? <Y> Enter or N (Press Enter for rotation of copies object about center, N for keeping objects in original orientation.)
STRETCH
Objec t c an be made longer or shorter with STRETCH. When ‘Stretc hed’,Line and Plines bec ome longer or shorter and Arc c hange radius to bec ome longer or shorter. Circ le do not stretc h; rather, they move if the c irc le is selec ted within the Crossing Window.
Methods for invoking the STRETCH c ommand inc lude:
Toolbar :
Pull-down menu : MODIFY > STRETCH
Command : STRETCH
An example of the stretc h c ommand prompt is as follows:
Command : STRETCH
Selec t Objec t(s) : to stretc h by c rossing-window or polygon Selec t Objec t : First Corner : PICK
Other Corner : PICK
Selec t Objec t : Enter
Base point or displac ement : PICK or (coordinates ) ( Selec t a point to use as the point to stretch from. )
Second point of displacement : PICK or (coordinates) (Select a point to use as the point to stretc h to)
Command :
EXTEND
Extend c an be thought of as the opposite of Trim. Objec ts suc h as Lines, Arc, and Pline c an be extended until intersec ting another objec t c alled a ‘boundary edge’ as in Figure 5.18. The c ommand first requires selec tion of existing objec t to serve as ‘boundary edge(s)’, whic h bec ome highlighted, then the objec ts to extend are selec ted. Objec ts extend until, and only if, they eventually intersec ts ‘boundary edge’. An Extended object ac quires a new endpoint at the boundary edge intersec tion.
Methods for invoking the EXTEND command include:
Toolbar :
Pull-down menu : MODIFY > EXTEND
Command : Extend
Command : extend
Select boundary edges : (Projmode = UCS, Edgemode = No extend )
Selec t Objec ts : PICK
Selec t Objec ts : PICK
Selec t Objec ts : Enter
<Selec t objec t to extend>/Projec t/Edge/Undo: PICK ( Selec t objec t to extend)
<Selec t objec t to extend>/Projec t/Edge/Undo: PICK
<Selec t objec t to extend>/Projec t/Edge/Undo: Enter Command :
Figure 18
Edge mode/Project mode
The edge mode and Projec t mode switc hes operate identic ally to their func tion with the Trim c ommand. Use Edge mode with the Extend option if you want a boundary edge object to be imaginarily extended.
Figure 19
FILLET
The fillet command automatically rounds a sharp corner ( intersection of two Lines, Arc s, Circ les, or Pline vertices ) with a radius. You only specify the radius and select the objec ts to be filleted. The objects to fillet do not have to completely intersect but can overlap. You c an spec ify whether or not the objec t are automatic ally extended or trimmed as nec essary ( Figure 5.20 )
Methods for invoking the FILLET command include:
Toolbar :
Pull-down menu : MODIFY > FILLET
Command : Fillet
The fillet command is used first to input the desired radius ( if other than the default 0.500 value ) and a sec ond time to selec t the objec t to fillet.
Command: fillet
( TRIM Mode ) Current fillet radius = 0.5000
Polyline/Radius/Trim/<Select first object>: r ( Indicates the radius option ) Enter fillet radius < 0.5000>: ( value ) or PICK ( Enter a value for the desired fillet radius or selec t two points to interac tively spec ify the radius )
Command:
Figure 20
CHAMFER
Chamfer is a manufac turing proc ess used to replac e a sharp c orner with an angled surface. In AutoCAD, Chamfer is commonly used to change the intersection of two Lines or Plines by adding an angled line. The Chamfer command is similar to fillet, but rather than rounding with a radius or “fillet”, an angled line is automatic ally drawn at the distanc es ( from the existing corner ) that you specify.
Methods for invoking the CHAMFER command include:
Toolbar :
Pull-down menu : MODIFY > CHAMFER
Command : Chamfer
Chamfer c an be c reated by two methods: Distance ( specify two distances ) or Angle ( Specify a distance and an angle ).
Distance option is used to spec ify the two values applied to c reate the c hamfer. The value indic ate the distanc es from the c orner ( intersec tion of the two line ) to eac h c hamfer endpoint ( Figure 21 ). Use the c hamfer c ommand onc e to spec ify distanc es and again to draw the chamfer.
Command: chamfer
(TRIM Mode ) Current c hamfer Dist1 = 0.0000, Dist2 = 0.0000
Polyline/Distance/Angle/Trim/Method/<Select first line>:d ( Indic ates the distanc e option )
Enter first c hamfer distanc e<0.0000>: ( value ) or PICK
Enter sec ond c hamfer distanc e <value of first distanc e>: Enter or PICK
Command:
Offset c reates a parallel c opy of selec ted objec t. Selec ted objec t c an be Lines, Arcs, Circ les, Plines or other objec ts. Two options are available with offset; offset a specified distance and offset through a spec ified point.
Methods for invoking the OFFSET command include:
Toolbar :
Pull-down menu : MODIFY > OFFSET
Command : Offset
Figure 22
DIVIDE
DIVIDE marks off a spec ified number of equal lengths on a selec ted objec t by plac ing point objec ts or bloc ks along the length or perimeter of the objec t. Valid objec ts that c an be divided inc lude arc s, c irc les, ellipses and elliptic al arc s, polylines, and splines.
Methods for invoking the DIVIDE command inc lude:
Pull-down menu : DRAW > POINT>DIVIDE
Command : Divide
1 From the Draw menu, choose Point Divide.
2 Selec t a line, arc , spline, c irc le, ellipse, or polyline.
3 Enter the number of intervals you want to represent.
AutoCAD places a point at eac h interval on the objec t.
The point objec ts that are added to the objec t c an be used for subsequent construction by allowing you to OSNAP to equally spaced intervals ( Nodes ). After using the Divide Command, the point objec ts may not be visible unless the point style is changed with the Point Style… dialog box ( Format pull-down menu ). A Regen must be invoked before the new Point style will be displayed. Figure 23 below shows Points displayed at the objec t.
The Measure c ommand will take an entity suc h as a line or arc and the measurement along it depends on the length of the segment. It similar with divide c ommand, ac c omplishes this by plac ing a point entity at a spec ified distanc e given in the measure c ommand.
Methods for invoking the MEASURE command include:
Pull-down menu : DRAW > POINT>MEASURE
Command : Measure
Figure 24 Using Measure to divide and measure the line with 3.0 inc hes length.
CHANGE
Using the c hange c ommand allows the c harac teristic s of an entity to be modified. The Change c ommand allows c hanging three options: Points, Properties or Text
Methods for invoking the CHANGE command :
Command : Change
Figure 23 : Using Change Command with c hanging point method
This point allows c hanging the endpoint of an objec t or endpoints of several objec ts to one position:
Command: Change
Selec t Objec ts :PICK
Selec t Objec t :Enter
Properties/<Change point>:PICK ( Selec t a point to establish as new endpoint of all objec ts)
PEDIT
This c ommand provides numerous options for editing polylines ( Plines ). The list of options below emphasizes the great flexibility possible with polylines. The first step after invoking Pedit is to selec t Pline to edit.
Methods for invoking the PEDIT command include:
Toolbar :
Pull-down menu : MODIFY > Object > Polyline
Command : Pedit.
An example of the Pedit c ommand prompt is as follows:
Command : Pedit
Selec t Polyline : PICK (select the polyline for subsequent editing )
Close or Open/ Join/Width/Edit Vertex/Fit/Spline/Dec urve/Ltype gen/Undo/eXit<X>: (option) ( Select the desired option from the sc reen menu or enter the c apitalized letter for the desired option.
Close
Close c onnec t the last segment with the first segment of an existing ‘open’ Pline, resulting in a ‘c losed’ Pline. (Figure 5.24 ). A c losed Pline is one c ontinuous objec t having no spec ific start or endpoint, as opposed to one c losed by PICKing points. A c losed Pline reac ts differently to the Spline option and to some c ommands suc h as
Fillet, Pline option.
Figure 24
Open
Open removes the c losing segment if the Close option was used previously. ( Figure 24 )
Join
This option join, or c onnec t, any Pline, Lines, or Arc that have exact matching endpoint and add them to the selec ted Pline ( Figure 25 ) Previously closed Plines c annot be joined.
Figure 25
Width
Width allows specification of a uniform width for Pline segment. ( Figure 26 ). Nonuniform width c an be spec ified with the Edit Vertex option.
Figure 26
Another methods that available under Pedit Command are Edit vertex, fit,
Spline,Dec urve, Ltype gen, Undo and Exit. Please prac tic e that methods
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