Lecture 04 Basic Modify Commands

7/31/2019 Lecture 04 Basic Modify Commands

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Basic Modify CommandsHere we'll cover the modify tools, which give us control over simple shapes we have created. As thename suggests - we can modify drawing elements.This is what the modify toolbar looks like (if you don't see it, check the modify box in 'view - toolbars'):

The modify tools (from left to right):Erase, Copy, Mirror, Offset, Array, Move, Rotate, Scale, Stretch, Lengthen, Trim, Extend, Break atpoint, Break, Chamfer, Fillet, Explode.

Erase - Select this button then a drawing element to erase it permanently from the drawing.

Copy - The copy command will copy any selected drawing elements and reposition where specified bythe user, without affecting the original elements.1)Select thecopybutton, then select the object(s) to copy then hit return (or right click)2) Select thebase pointwhere to copy from (For example if copying a circle, it would be sensible for thebase point to be the centre of the circle)3)Enter thesecond point of displacement - this is where the new base point of the copied objects is tobe positioned. Note that the base point is not visible, just a co-ordinate in Autocad's drawing system toenable accurate positioning of objects where required. When quickly copying an object it is quite acceptable to simply pick a rough point to copy and thenposition an object without specifying co-ordinates, it can then be accurately positioned in the drawing areausing the move command.

Mirror - The mirror command will create a mirror image of any selected drawing elements along any lineof symmetry specified by the user.Mirror Tutorial Files:

Lesson6 - mirror.dwg(AutoCAD 2000/2002 File Version)Lesson6 - mirror R14.dwg (AutoCAD R14 File Version)

1) Openthe drawing file. It should look like the one shown below:
http://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson6%20-%20mirror.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson6%20-%20mirror.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%203/lesson3.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%203/lesson3.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%203/lesson3.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson6%20-%20mirror.dwg


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2) Select themirrorcommand from the modify toolbar (or choose 'modify - mirror' from the drop down

menus)

3) Selectthe blue object (Looks like half a wine glass?!)4) We are now prompted to specify the first point of the mirror line, choose the centre of the cross marked'A'5) We now need to enter the second point of the mirror line, select the centre of the cross marked 'B' Handy Tip!: To draw a true vertical or horizontal line, hit F8 or click 'Ortho' at the bottom of thecommand line to enable Autocad's Ortho function, which limits the available pointer selectionpoints to horizontal or vertical positions relative to the first point selected. Ortho can be used withall commands.6) Autocad now asks if we want todelete the source object. We need to enter 'Y' for yes or 'N' for no(simply hitting enter would accept the default setting of 'no'). Deleting the source object results in amirrored copy of the original object, without the original object. In this case we want to keep the originalobject to complete the drawing. EnterNfor no followed by enter.You should now have a simple drawing of a wine glass as below.


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Offset - Offset will make a copy of a line or series of selected lines by a specified distance in the directionspecified. The example below shows an original red box (50mm x 50mm) with an offset yellow box 10mmto the outside of the original box.


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The offset command simply creates a copy of the selected objects, at the distance specified, to eitherside of the original object.

1) Create a new drawing and draw arectangle from a base point of co-ordinates10,10at a size50,50.

2)Select the offset command

3) When prompted for an offset distance, enter10 .4) When asked to select an object, select the rectangle we drew.5) Autocad then asks for aside to offset. If we select a point outside of the rectangle then a newrectangle will be created outside of the original at a 10mm offset. Selecting a point within the rectangle


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would create a rectangle within the existing rectangle at a 10mm offset.Select a point outsideof the rectangle.You should have an image similar to the one shown above. Offset can be used on any shaped objects,polylines, lines rectangles, circles etc and can be a very useful command. The top arc piece of the wineglass tutorial above was originally drawn using the offset command to give a thickness to the glass.

Array - The array command quickly creates copies of a selected object(s) to a specified spacing. Thearray command can save lots of drawing time when used correctly. There are two types of array;rectangular and polar. A rectangular array would create copies of an object in rows and columns atspecified spacings. A polar array would create copies of an object in a circular pattern based on aspecified centre point.Shown below are the two types of array. The red objects are the original objects, and the yellow are thecopies created with the array.

Rectangular ArrayDownload the appropriate tutorial file for your version of Autocad:

Lesson6 - Array.dwg(AutoCAD 2000/2002 File Version)Lesson6 - Array R14.dwg (AutoCAD R14 File Version)(Autocad R14 Array options are not in a dialogue box although the same settings apply)The drawing is a plan view of a chair. We will use the array command to create more chairs at a regularspacing of 1000mm centres as shown in the above example.
http://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20array.dwg


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1)Open the Autocad file, select thearraybutton

2)Select 'rectangular array'3)Forselect object,select the chair4) For the rows and columns, we will select5each time. This tells Autocad to repeat the object 5 timeshorizontally and 5 times vertically.5) For column offset and row offset enter 10006) Autocad 2000,2002 users select the OK button.

An array will have been created with the rows, columns and spacings specified. Your drawing should besimilar to the rectangular array drawing shown above.

Polar ArrayDownload the appropriate tutorial file for your version of Autocad:

Lesson6 - Polar Array.dwg(AutoCAD 2000/2002 File Version)Lesson6 - Polar Array R14.dwg (AutoCAD R14 File Version)

(Autocad R14 Array options are not in a dialogue box although the same settings apply) 1)Open the Autocad file, select thearraybutton

2) Select 'polar array'3) Forselect object, select the entire drawing (the circle and vertical line)
http://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array%20R14.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwg


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4) Forcentre point, choose the bottom end of the vertical line. This is the point where the copies of theoriginal object will be rotated about.5) For number of items, enter12.6) For angle to fill, enter360.(we have just told Autocad to array 12 items about the centre point for a full 360)

Your drawing should look similar to the one shown below:


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Move - The move command works exactly the same as the copy command described above, exceptinstead of creating a copy of the selected objects, the second objects are moved.

Rotate - The rotate command rotates any selected objects about a defined point by the angle specified.By default Autocad will rotate objects anticlockwise when an angle is entered.1)Load the drawingLesson6 - Polar Array.dwgthat we used in the polar array example.2) Select therotatebutton from the modify toolbar.3)Selectthe vertical line and circle.4)Select the base pointfor the rotation. This is the point which the selected objects will be rotatedabout. Select the bottom end of the vertical line.5) Autocad asks for a rotation angle. Note how mouse movements rotate the object in real time enablingquick rotations to be made. We will specify an angle of 45. Enter45and hit enter.
http://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwghttp://c/Documents%20and%20Settings/Rick%20Wasinger/My%20Documents/My%20Web%20Sites/mysite4/Tutorials/Lesson%206/lesson%206%20-%20%20polar%20array.dwg


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The object should have been rotated as shown above.

Scale- The scale command scales the size of a selected object(s) by a defined scale factor from aselected base point. The selected objects can be scaled up to increase size or down to reduce the size.For example:Entering a scale factor of 2 would result in the object being doubled in size.

Entering a scale factor of 0.5 would result in the selected object being halved in size.Try scaling the object we rotated in the above rotate tutorial, to get a feel for how the scale commandoperates.

Stretch - The stretch command will stretch a selected part of an object, and can be used to lengthen orshorten a particular object.Looking at the stretch command introduces two very different ways of selecting objects. So far you haveprobably been 'picking' an element of a drawing with one single click of the mouse while the cursor is overthe object. A quicker way is to pull a window over the objects we want to select.

There are two ways to select objects with a window, with each method yielding different results. A windowdrawing a box from top left to bottom right will select all objects FULLY within the window. Drawing awindow with a box from bottom right corner to top left will result in all objects being selected that ANY partof the window passes through.


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The selection window (shown green) with a box drawn top left to bottom right results in the objects within

the window being selected as shown on the second image shown above. Note that the circle only partiallywithin the window does not get selected.


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The selection window shown green above (Note how the different window selection type is shown asdotted) results in all objects within and passing through the selection window become selected.Now we know the different selection types we can have a go with the stretch command.1) Download and open the original polar array lesson drawing above.2) Select thestretchcommand button

3) Use the bottom right to top left window type to draw a dotted window around the end of the object asshown below:


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4) AutoCAD asks for abase point, select around where the line and circle meet.5) Notice how where we move the mouse the object is becoming stretched. We can simply select a pointwith the mouse to stretch the object, or enter a more accurate position such as @0,50 .

Lengthen - The lengthen command will lengthen a selected line.

When the lengthen command is activated, before the line is selected, we need to tell Autocad how we

will lengthen the line.

DE - Delta: Autocad asks for a distance to lengthenthe line by, when the line is selected it will then belengthened by the specified distance ONLY to the side of the line where the line was selected. i.e If whenyou selected the line, you selected it just to the left of centre, then the left side of the line would belengthened.P - Percent: Autocad asks for a percent to lengthen by, then asks you to select the line. Specifying 50%

would reduce the size of the line by half (The same effect as scaling by a factor of 0.5). Specifying 100%would result in no change in length. 200% would double the length of the line. When specifying thepercentage to Autocad only the numerical figure has to be entered and not the percent (%) symbol.T - Total: Autocad asks for the distance you want the entire line to be, when you select the line it willadjust the lines length to the distance specified.


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DY - Dynamic: Autocad adjusts the length of the line as the mouse is moved in the direction the line is tobe lengthened. This is not an accurate technique, although is useful for quickly lengthening constructionlines for example.

Trim - The trim command is an extremely useful tool which will erase all parts of an object beyond orwithin its intersection with another object.

The protruding yellow lines on the image on the left have been trimmed to the edge of the rectangle asshown on the right image

The trim command is easy to execute provided that this one very important rule is obeyed:

When first prompted for an object, you MUST choose the object you wish to use as the 'cuttingedge' and not the object to be trimmed.

i.e the cutting edge in the above example was the rectangle, the vertical and horizontal lines weretrimmed to this edge.Trim Tutorial Files:

Lesson6 - trim.dwg(AutoCAD 2000/2002 File Version)

Lesson6 - trim R14.dwg (AutoCAD R14 File Version)We are going to trim the yellow lines in the drawing to end at the inside of the rectangle as shown in theimage above.

1) Open the above tutorial file into Autocad. Choose thetrimcommand
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2) When asked toselect object we need to select the object(s) which will be the cutting edge!In thiscase it is the rectangle so select it and hit enter.We now are asked to select the objects to trim. It is important to note that where we select the object tobe trimmed in relation to the object selected as the 'cutting edge' determines which part of the trimmedobject is deleted, and which remains. If we were to select part of the yellow lines within the rectangle,

then the selected objects would be deleted up to the inside edge of the rectangle (cutting edge). We wantto remove the sections of the lines outside of the rectangle so:3)Selectall 4 of the ends of the yellow lines OUTSIDE of the rectangle. Notice how they are removed aswe select them.4) Hitenterto end the trim command.

Just remember, be aware what is your cutting edge! The trim command can be used on most objectswithin Autocad. One common mistake beginners make is that they can't understand why Autocad refusesto trim a circle to a single line which intersects the circle at one point only. If the circle were to be trimmedto one line, it would be deleted! Any trim command on a circle must have two 'cutting edges' selected.

Extend - The extend command is similar to the trim command in how it functions, except it extends aselected line to a point of intersection of another selected object. In order to successfully use thecommand, you have to make sure that when the line is extended it will actually intersect the objectselected which the line is to extend to!1) Download the trim tutorial file above and use the trim command we learnt to trim the yellow lines to thecircle as shown below:


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We will now use the extend command to extend the yellow lines back up to the edge of the rectangle

1) Select theextendcommand

2) When asked to select an object select the boundary edge which the lines will be extended to. In thiscase we want to extend to the rectangle, soselect the rectangle.3) We are now asked to select the object to extend. As with the trim command, the effect of the commandis dependant upon whereabouts along the length of the object it is selected. Autocad will always extendthe end of the line which is nearer to the point where the line was selected. Select each end of the yellowlines (near the intersection with the circle) to extend each line up to the rectangular boundary edge weselected.4) Hit enter to end the command.

Break at Point - The break at point command enables the user to break an object at a specific point,

creating two separate objects.1) Draw alinethat is roughly horizontal, don't worry about its size.

2) Select thebreak at pointcommand . When prompted to select object, select the line we just drew.3) When prompted toselect a break point, select somewhere along the length of the line.

Now try selecting the line, note how it is now broken into two separate lines, at the point we selected. Thiscommand can be used on most drawn objects within Autocad.

Break - The break command is identical to the above break at point command, except the break line isn'tas neat as when using the above command i.e the break point leaves a significant gap between what is

now two separate objects:

The top line was broken with 'break at point'. The bottom line was broken with the standard 'break'command.

Chamfer - The chamfer command will chamfer the intersection of two lines to a specified distance. This isbest shown with the example below:


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The rectangle on the left is 50mmx50mm. The rectangle on the right has been chamfered by a distance of5mm.1) Draw a rectangle using thelinecommand (NOT rectangle - we will see later) at a size of 50mm x50mm.2) Select thechamferbutton

3) We are going to chamfer the50x50rectangle by a distance of 5mm (as seen above). EnterDfordistance then hit return.4) Autocad asks for the first chamfer distance. Enter5then enter.5) Autocad then asks for the second chamfer distance. In this case we are using the same chamferdistance, although Autocad can draw a chamfer with two separate distances. As we want the samedistance, input5then enter.We now need to select the two lines to chamfer. This would be the two intersecting lines we wish tochamfer.6) Select the first line to chamfer then enter.7) Select the second line then enter.The two line segments should be chamfered similar to the diagram shown above. Repeat this procedureto chamfer the remaining 3 corners.You may have wondered why we drew the rectangle using the line command instead of the much quickerrectangle command. This is because the rectangle command draws the rectangle in the same manner as


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a polyline. We can't select the individual lines forming the rectangle, so we can't select the separate lineswe wanted to chamfer. There is however a way to chamfer two polyline segments:1) Draw arectanglewith dimensions50x50.2) Select thechamferbutton , and this time enterPfor polyline.3) Autocad asks for a 2D polyline,select the rectanglewe drew.Autocad automatically chamfers each intersecting line segment of the polyline to the last specifiedchamfer distance used (which should be 5mm as specified in the first part of the chamfer tutorial).To change the chamfer distance simply select the chamfer button, specify distance, enter the chamferdistance, when prompted to select an object simply hit return until out of the chamfer command. Your newchamfer distance will now be set.Handy Tip: To join the ends of two separate lines, use the chamfer command with a distance of 0 !

Fillet - The fillet command is very similar to the chamfer command above, except instead of creating astraight line chamfer, Autocad creates a radius between the two points.

The rectangle on the left is 50mmx50mm. The rectangle on the right has been filleted by a radius of 5mm.The command works exactly the same as the chamfer command, except we must specify a radius ratherthan a distance. We'll go through the process just incase you're unsure:1) Draw a Rectangle using thelinecommand, with a size of50x50.2) Select thefillet button


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3) We will specify a radius, so enterRfor radius4) Autocad asks for the fillet radius, enter 5 then hit enterThe fillet radius is now set.5)Select the first line segmentto fillet then hit enter6)Select the second line segmentto fillet then hit enterThe two lines will have been filleted with a radius of 5 as we specified. Repeat the procedure to fillet theremaining 3 corners.As with the chamfer lesson above, we can apply the fillet command to a polyline which will fillet allintersecting lines. While using the fillet command be careful not to specify a radius too large.

Explode- The explode command is very straightforward. It simply breaks down an object object down toits basic line entities.

For example, a rectangle drawn with therectanglecommand is drawn as a polyline, the separate lines

making the rectangle can't be selected or edited. If we choose theexplodebutton , then select therectangle object, it will be broken down (or exploded!) into its 4 separate lines.

Explode can also be used to break apart a block and also hatching (covered later).A basic rule of thumb would be: If you can't select an object you wish to edit, or wish to edit only part of anobject, try exploding it to break it down to its basic form of lines and arcs.

That concludes our modify tools tutorial. With the modify commands covered in this tutorial, you shouldbe able to create most 2D drawings you would ever need too! (Of course - combined with the basic drawtools covered earlier).