More about this will be discussed later in this book. Switching from Model Space to Paper Space and vice versa can be effected by clicks on the Model or Layout tabs just below the drawing area. Templates 35 Revision tips 1. To open a template click New. Drawings in this book are usually constructed in Model Space. Paper Space will be used in later chapters. Further worked examples involving the Circle and Arc tools. Further examples of constructing drawings to absolute coordinate entry.
Worked examples involving the use of constructions involving absolute coordinate entry. Worked examples of using the tracking methods of determining accurate lengths when constructing drawings. Using Object Snaps. Using AutoSnap. Using Polar tracking. The importance of using Snap and Ortho. The Circle and Arc tools A simple example of using these two tools was given in Chapter 1. The worked examples given below show further methods of using them.
Similarly a circle can be drawn through two points. First example — Circle — the Ttr response 1. Call Circle again. Second example — the Arc tool prompts The number of different methods of using the Arc tool for drawing arcs can be seen by selecting Arc from the Draw drop-down menu Fig. The Arc sub-menu shows the choices available. Constructions using absolute coordinates Deferred Tangent Some simple examples of constructions drawn by entering points on an Fig.
Two further icon examples are given here. Once a start point for a construction has been entered, coordinates are entered relative to the last point entered. Relative coordinate entries can be made in conjunction with absolute entries. First example — relative coordinate entry Fig. Specify point on object for first tangent of circle: pick Specify point on object for second tangent of circle: pick Specify radius of circle: 25 Command: Repeat for the other R25 circle followed by the two R15 circles.
Pressing the keys Ctrl and D simultaneously toggles between the coordi- nates showing as absolute numbers to relative numbers to the numbers being greyed out. If the rubber band is dragged in a chosen direction and then a number enter at the keyboard, followed by a right-click, a line is drawn of the entered length in the direction dragged by the rubber-banded line.
Example — tracking Fig. As the name implies, object snaps or osnaps are designed to ensure that when new objects are added to a drawing they snap onto exact positions relative to other objects on screen. Osnaps can be set by entering os at the command line, which brings the Drafting Settings dialog on screen Fig. In Fig. Another way of using osnaps is to turn them off and to enter abbrevia- tions for the osnaps at the command line. The most frequently used of these abbreviations are: end — Endpoint.
Draw the two circles given in Fig. Defferred Tangent Center Quadrant Fig. To set AutoSnap on right-click in the command window and from the right-click menu which appears click Options.
The Options dialog appears Fig. In the dialog click the Drafting tab and ensure the check boxes against the AutoSnap options are all on ticks in boxes. With all the AutoSnap options set on another feature appears with osnaps — the AutoSnap aperture box as shown for Endpoint Fig.
Accuracy when drawing 45 Fig. In the ensuing sub-dialog select 5 from the Increment angle popup list and click the radio buttons against Track using all polar angle settings and Relative to last segment to set these parameters on dots in circles. When such settings have been made and the POLAR button in the sta- tus bar is set on, when objects are added to existing objects a tooltip such Endpoint as that shown in Fig.
Note Fig. Another method of toggling Polar tracking is by pressing the F10 function key. An example of a drawing involving decimals Fig. Now using the Line tool, construct the drawing given in Fig. The cursors are not able to be moved to any position not a snap point. If a drawing in 5 unit intervals is being constructed, full use can be made of these snap points. This does not prevent the effective use of osnaps which override snap points or when lengths other than multiples of 5 are drawn, say by tracking.
Accuracy when drawing 47 When a drawing has been constructed it is advisable to save it to a floppy disk. The Ttr prompt of the Circle prompts sequence is used to draw cir- cles tangential to other objects on screen. When using relative coordinate entry each next point is at a length and angle to the object from which it is being drawn. Use Object Snaps to snap to parts of objects on screen. AutoSnap is of value at times. Polar tracking gives length and angle tooltips for the next object to be drawn.
Set the Precision number in the Units dialog to construct objects with precise length to a number of decimal places. Do not attempt adding dimensions. Using the Line and Arc tools, construct the plate shown in the drawing given in Fig. Construct the given drawing. Set Precision in the Units dialog to 4 numbers after the decimal points and then using the tracking method construct an accurate copy of the drawing in Fig.
Construct the drawing in Fig. Note The two exercises 5 and 6 involve the drawing of two-view orthographic projections see Chapter They also involve the use of Hidden lines for showing hidden detail and Centre lines which are drawn through the centre of all circular parts of a drawing.
To draw hidden detail lines, first click in the area of the Layers field and again on the layer name hidden. The layer name appears in the Layers field which makes the hidden layer current Fig. Similarly centre lines are added to a drawing following the setting of the centre layer as current.
The major difference between the Line tool and the Polyline tool is that a rectangle, say, constructed with the line tool will consist of four objects, whereas a rectangle constructed using the Polyline tool is a single object in its own right. But, in addition to drawing lines with the tool, polylines plines can be drawn to any width and can be drawn as arcs.
To call the tool, either left-click on its tool icon in the Draw toolbar Fig. Third example — Polyline — Circle Fig. Call Polyline and construct the two plines shown in Fig. Construction lines are used to lay out a foundation in which drawings can be constructed.
When drawing construction lines they should be drawn on a new layer of Construction preferably of a colour not used for other layers. An example of such a layer showing in the layers popup list is given in Fig. In the layers popup list click Construction to make that layer current. When complete, click the 0 layer in the layer popup list to make layer 0 the current layer. Using the construction lines as guidelines construct the outlines of the three-view orthographic projection see Chapter 10 as in Fig.
More tools from the Draw toolbar 57 Fig. Set layer Hidden current and add hidden detail. Set layer Centre current and add centre lines. The result is given in Fig. The two features of regular polygons are — all sides are the same length and all angles are the same size. Note that polygons drawn with this tool are polylines. To call the tool either click the Polygon tool icon in the Draw toolbar Fig. When called the command Fig. Call the Polygon tool.
Repeat to construct a six-sided polygon circumscribed about a circle of radius 55 of centre ,, drawing 2 of Fig. Now construct polygons of sides 7 inscribed , 8 circumscribed , 9 circumscribed and 10 inscribed and of Edge length — Drawings 3, 4, 5 and 6 of Fig.
The centres are shown in Fig. When the tool Fig. When the two rectangles had been constructed they were placed in a SW Isometric viewing position by clicking on Views in the menu bar and clicking on 3D Views, followed by another click on SW Isometric in the sub-menu which appears.
Rectangle at Elevation of 80 and Thickness 5 Fig. What is seen is an ellipse. Circle from Circle as seen which ellipse from left results is derived in an ellipse Fig. To call the Ellipse tool, either click its tool icon in the Draw toolbar Fig. When called, the command Fig. Call the Ellipse tool: Fig. Set to 0, ellipses will be drawn as true shapes. If set to 1, ellipses are polylines. To call the tool, either click its tool icon in the Draw toolbar Fig. The hole in the arm may be an incorrect size.
The revcloud is drawn around the part to draw attention to the problem. If required, the size of the point can be set in the Point Size field. Revision tips 1. A closed polyline is a single object no matter how many sides it possesses. Construction lines should be drawn on a specific layer. Construction lines are of infinite length.
A polygon can be drawn, given the radius of a circumscribing circle or the radius of an inscribing circle or the length of one of its edges. Rectangles drawn with the Rectangle tool are plines. Polygons drawn with the Polygon tool are plines. A setting of 0 results in a true ellipse and a set- ting of 1, a pline. Ellipses have two axes — a major and a minor.
The major ellipse can be regarded as the same length as the diameter of the circle from which the ellipse has been derived.
Use the Revcloud tool to emphasise part of a drawing. The drawing shown in Fig. Plines of width 1 Fig. Construct the arrows given in Fig. Draw the construction lines on the Construction layer and the outlines of the three views on layer 0. More tools from the Draw toolbar 67 45 All plines of width 2 15 Fig. Introduce the tools in the Modify toolbar. Show methods of modifying drawings or parts of drawings using tools from the Modify toolbar. The Modify toolbar As the name of the toolbar implies, tools in this toolbar are designed to modify constructions already on screen.
These tools have a similar import- ance to those in the Draw toolbar in that they are among the more fre- quently used tools when working in AutoCAD All the tools in the toolbar except the Erase tool the tool icon at the left-hand of the toolbar in Fig. The Erase tool has been shown in worked exam- ples in Chapter 1 and the use of the Explode tool will be described in Chapter Call the Copy Object tool. Base point Second point Fig. Enter u at the command line to undo the copy.
Call Copy Object again. Call the Mirror tool. The variable is set as follows: Fig. The mirroring for both examples are shown horizontally and vertically. Construct drawing 1 as a pline of width 0.
With Mirror, mirror draw 1 to produce drawing 2. With Pedit join the two plines to form a single pline. Call Offset. The command line shows: Fig. Other examples — Offset Fig. Draw- ing 2 shows an offset outside the ellipse by 10 units, drawing 3, an offset inside the ellipse by 2 units and drawing 4 shows offsets both inside and outside the ellipse by 5 units.
Two types of array are possible using the tool — Rectangular arrays and Polar arrays. First example — Rectangular array Fig. Construct a hexagon of edge length Using Offset, offset the hexagon both inside and outside. Call the Array tool. Make entries in the dialog as shown in Fig. Enter 5 in the Rows field and 8 in the Columns field. Click the Select objects button.
The dialog disappears. Window the the Modify toolbar three hexagons and right-click. The Modify tools 75 Fig. The dialog reappears. Click its Preview button. The dialog again dis- appears. The proposed array appears on screen together with another Array dialog Fig. If satisfied, click the Accept button. If changes are thought to be needed, click the Modify button when the Array dialog will reappear to allow changes to be made to the settings.
The result is shown in Fig. Second example — Polar array Fig. Construct a semicircular pline of width 0. Call the Array tool and make settings as shown in Fig. Total number of items: field enter Angle to fill: field enter although that figure may be in the field anyway. Click the Pick center point button and when the dialog disappears click the point , Click the Preview button.
The array appears together with the smaller Array dialog. If the array is satisfactory click the Accept button. If not satisfactory click Modify, and in the dialog make new settings. When finally satisfied with the array click the Array Accept button. The result is given in the right-hand drawing of Fig. Note 1. In Rectangular arrays the numbers in the Row offset and Column offset fields may be negative — if the rows of the array are to be down- wards from the objects to be arrayed, the Row offset field should carry negative numbers.
Similarly if the array is to be to the left of the objects to be arrayed, the Column offset figures should carry negative numbers. The Modify tools 77 Fig. Objects in Polar arrays can be arrayed in circular arcs of any angle. To set the angle enter the required angle in the Angle to fill field. To call the tool either click its tool icon in the Modify toolbar Fig. The Rotate tool When using this tool remember the default rotation direction in AutoCAD is counterclockwise anticlockwise. Examples — Rotate Fig.
Construct the arrow shown in Fig. With the Copy Object tool multiple copy the arrow seven times. Call the Rotate tool. Repeat with the other copies rotating to the angles as shown in Fig. Call the Move tool and move each copy to a more suitable position. Construct the square and circle shown in Fig. Add the horizontal band across the centre of the SQ40 circle using a pline of width of Copy the drawing five times.
Call the Scale tool. Repeat with the other four copies scaling to the factors given in Fig. If necessary, with the Move tool move the scaled drawings so more suitable positions in the AutoCAD drawing area. The results are shown in Fig. Base point Scaled 1. Copy the drawing twice. Call the Stretch tool either with a click on its tool icon in the Modify toolbar Fig. The left- hand of the pair of drawings shows the crossing window and the base point or displacement point.
The right-hand drawing shows the result of stretching to the second point of displacement. In this example note the circle crossed by the crossing-window is unaffected by the stretch. The central pair of drawings shows the result when the circle is included in the crossing-window.
The circle moves with the stretch. The lower pair of drawings shows the distortion which can take place when the crossing-window crosses an arc. First example — Trim No extend Fig. Call Trim either with a click on its tool icon in the Modify toolbar the Modify toolbar Fig.
Select objects: pick one of the lines 1 found 20 Select objects: pick the other line 1 found. Repeat to trim the lines away from the circle. Cutting edges Result — first trimming Object to trim Cutting edge Result — second Object to trim trimming Object to trim After pedit to join and of width 2 Fig.
Construct the pline and the pline arcs shown in Fig. Call Trim. Select objects: pick one of the lines 1 found 80 Select objects: pick the other line 1 found. Select objects: pick one of the lines 1 found Select objects: pick the other line 1 found. The same effect is obtained by using the Extend tool. Examples — Extend Fig.
Draw two plines as indicated in Fig. Call Extend. Drawings 7 and 8 of Fig. The left-hand arc of the two arcs extends to what would have been the fully extended arc of the right-hand arc. The difference between the two tools is that the Break at Point tool can be used to break an object into parts, whereas the Break tool can be used to break portions from an object.
Note that circles cannot be broken using this tool. Examples — Break Fig. Construct a pline drawing 1 , a circle drawing 3 and a rectangle drawing 4. Taking the line and the circle as examples, call Break either with a the Modify toolbar click on its tool icon in the Modify toolbar Fig.
Note that when breaking a circle the break must be made in a counterclockwise direction. The Chamfer tool Examples — Chamfer Fig. Construct three rectangles using the Line tool drawings 1, 2 and 4 and a fourth rectangle using the Polyline tool drawing 3. Call Chamfer either with a click on its tool icon in the Modify toolbar in the Modify toolbar Fig. Drawing 2. Drawing 3. Drawing 4. The results on the four drawings are shown in Fig.
The Fillet tool Examples — Fillet Fig. Construct two rectangles using the Line tool drawings 1 and 2 and a pline rectangle drawing 3. Drawing 1. Call the Fillet tool either with a click on its tool icon in the the Modify toolbar Modify toolbar Fig. The Copy Object tool can be used for making single or multiple copies of objects. When using the Offset tool the offset distance can be set by picking two points on the screen for the distance.
Arrays can be Rectangular or Polar. When setting rectangular arrays, set Y distances must be negative in the perpendicular downward direc- tion. Polar arrays can be of any required angle. When using the Rotate tool bear in mind that the default rotate direc- tion is counterclockwise anticlockwise.
When stretching using the Stretch tool, bear in mind that circles are unaffected by the stretching if the crossing window passed through the circle. The Trim and the Extend tools allow trimming and extension to implied extensions. The Break at Point tool is used to break objects into two parts. The Break tool is used to break gaps in objects. The Chamfer and the Fillet tools have similar prompts sequences, the main difference begin that when chamfering two distances are required, whereas when filleting only the radius requires to be stated.
Construct Fig. Fillet its corners to a radius of The plines should finish at a width of 1. To construct Fig. Call Stretch and stretch the drawing vertically down- wards by 20 units.
R20 Offset 5 10 90 40 Plines 75 tangential to ellipse Fig. Stretch the drawing horizontally by 50 units with the crossing window to the left of the right-hand ellipse. Stretch the drawing horizontally with the crossing win- dow passing through the centre of the right-hand ellipse. Note In this exercise it will be noted that when stretching the ellipses they changed shape. If you now reset the PELLIPSE variable to 0 and draw an ellipse and then try stretching, you will find that a true ellipse resists being stretched in any direction.
The clip has been drawn as polylines of width 0. Describe the variety of dialogs available in AutoCAD Illustrate the types of menus available in AutoCAD Introduce the text fonts available in AutoCAD Show how text styles are set in AutoCAD Dialogs Reference has already been made to dialogs and the parts of a dialog have been shown in an illustration on page 2. There are a large number of dialogs in AutoCAD used for the setting of parameters for a wide range of operations. Some dialogs are com- plex including as they do the possibility of making a whole range of settings for a variety of features.
Some of the features in this dialog are shown in Figs 7. Also shown in this illustration are the popups from the arrows to the right of Views and Tools in the same area of the dialog. Note that for this Internet page to appear the Internet must be open in the computer in use. Autodesk is the firm which publishes AutoCAD.
The Options dialog Another complex dialog is the Options dialog. Right-click anywhere in the command window Fig. This dialog Fig. Click each tab in turn and examine the sub-dialogs which then appear. Warning windows Warning windows such as that shown in Fig. The operator must decide which button to click when they do appear.
Menus Several types of menu will be seen in AutoCAD Drop-down menus appear when a name is clicked in the menu bar. All of these are shown in Figs 7. Dialogs, menus, text 93 Fig. Right-click menus appear with a right-click in some situations. Some sub-menus from drop-down menus Fig. Dialogs, menus, text 95 Fig. Among other right-click menus are: 1. Toobars list: a right-click in any toolbar on screen bring a menu show- ing all the available toolbars Fig.
Pan: see Fig. Osnaps can be selected from this menu. If thought necessary several other text styles could be included by adding to those already in the Text Style dialog. The method of adding text styles has been described on page Notes 1. There are two methods of entering text into a drawing in the AutoCAD drawing area. First example — Multiline Text Fig. Call the Multiline Text tool with a click on its tool icon in the Draw toolbar Fig. Drag the corner of the box to the size in which text is to be placed.
With the pick of the opposite corner the Text Formatting dialog appears above the box which changes appearance as shown in Fig. The text appears placed as required in the AutoCAD window. Note The size of the box in which text has been entered can be adjusted — drag the corner of the rectangle at the top of the box in which text has been entered as indicated in Fig. Note that the unit length of the dragged Fig. If at the second prompt Enter text: further text is typed, it appears below the first line of text.
Several lines of text can be entered in this manner. Right-clicks have no effect when using this tool. In the Font name popup list of the Text Style dialog, the fonts are shown with one of two icons against their names. A few examples of the types of fonts are shown in Fig. Either enter ddedit at the command line or from the Modify drop- down menu, pick Object, the Text and finally Edit. Dialogs, menus, text Fig. Using normal word-processing methods correct the text in the Text field Fig.
The corrected text replaces the old wrongly spelt text. Second example — the Check Spelling tool 1. Place some badly spelt text on screen. At the command line enter spell or sp. The command line shows: Command: enter sp right-click Select objects: pick the text Select objects: right-click The Check Spelling dialog appears Fig. In its Suggestions field a word for the first of the wrongly spelt word in the text appears. Click the Change button and the word is corrected.
If the word in the Suggestions field is not that which is required, a click can be made on a word from the list below the field bringing that suggestion into the field. Click Change and the change is effected. Click its OK button. The dialog disappears and the text should now be spelt correctly.
The Autodesk website www. To get into the Internet from this dialog, the Internet must be running at the time on the computer in use. An outward facing arrow appearing after a name in a drop-down menu shows that a sub-menu will appear with a left-click on that name.
If three fullstops appear after a name in a drop-down menu. Use right-click menus where appropriate. The rectangle in which text is entered when in Mtext can be re-sized by dragging at its end line. SHX fonts can only be entered in a single style. But do not save the screen — otherwise your template may not appear in a correct fashion. Use the tool Mtext tool to enter some very badly spelt text on screen.
Then correct the text using the Edit Text dialog. Now use Dtext for the same purpose. Open the Internet by whatever method the computer uses and have a look at the Autodesk website. To give further information about Layers and their uses. To describe further settings from the Options dialog. To describe the use of Lineweights. To describe uses of the Polyline Edit tool. To introduce the Express tools. To explain Grips.
Further details are given here. The technical drawing in Fig. In the same way as certain details when working by hand can be drawn on sheets of tracing paper, which can be placed over the main drawing when required or taken away when not, so layers in CAD drawings can be turned off or back on again and also shown or hidden. Layers in CAD drawings go fur- ther in that layers can be frozen, the advantage of which allows speedier regeneration of drawings.
Layers can also be locked in which case nothing on that layer can be modified although objects can be added to the layer. The meanings of the icons are shown in tooltips appearing when the cursor is placed over the icon. Limit to number of layers in a drawing There is no limit to the number of layers which can be set when working in AutoCAD Some technical drawings, particularly those for architec- ture and building may require a very large number of layers.
Layers and other features Fig. This is because a black area may be easier to look at when working in AutoCAD and also that colours such as yellow and green show more clearly against a black background. To change the colour, in the Options dialog click the Display tab and in the sub-dialog click the Colors. Then in the Color Options dialog which appears click in the drawing area of the Model tab icon and select Black in the Color popup list Fig.
The pick box size can be adjusted in this sub-dialog by adjusting the slider to the right of the Pick box size area. So also can the colours and size of the Grips Size. More about grips later in this chapter. The various possibilities for settings should be examined in the various sub-dialogs of the Options dialog. Lineweights In the Properties toolbar click the arrow to the right of the field labelled, By Layer.
The popup list which then appears shows a range of lineweights Fig. These were selected from the lineweights popup list. If layer 0 is set with a lineweight of say 2. But when the drawing is plotted or printed then the lineweight takes effect. This is shown in Figs 8. It is only when the drawing is plotted or printed that the lineweights show. Note Lineweights will not apply to polylines which can have line widths set as they are included in a drawing.
But features such as hidden lines, centre lines and dimensions will be printed at the lineweight set in the layers on which such objects have been drawn. Features such as text are obviously not affected by lineweights. The Polyline Edit tool The tool can be called with a click on Object in the Modify drop-down menu, then in its sub-menu, click Polyline Fig.
It is easiest to enter pe at the command line. The tool is used for changing polylines in a variety of ways. It can also be used for changing lines, which have to be made into polylines. Construct a pline rectangle as shown in drawing 1 of Fig.
Copy the rectangle five times to give rectangles 2, 3, 4, 5 and 6. Repeat for drawing 3 entering s Spline in response to prompts. Repeat for drawing 4 entering e Edit vertex and then m Move. Repeat for drawing 5 entering f Fit in response to prompts. Repeat with drawing 6 entering o Open in response to prompts.
When the last pline has been picked finish selecting with a right-click then specify the desired change. Layers and other features Express tools Express tools can be loaded with AutoCAD as an extra set of advanced tools covering the types of operation which readers of this book are unlikely to need to use.
To see the diversity of these tools if they have been loaded in the computer in use click Express in the menu bar. To see the variety of tools in the resulting drop-down menu click each name in turn. Two of the sub-menus — Layers and Text are shown in Fig. Every time an object is selected at any point with a left-click, Grip boxes appear at various points around the object.
The size Fig. Drag the selected grip to another position and the object stretches — drawing 1 of Fig. Click a grip on the pline circle. Right-click and a right-click menu Fig.
From the menu select Scale and in response the Specify Scale factor prompt enter 0. The object scales to half size drawing 2 of Fig. Click a grip on the circle. Right-click and from the menu select Mirror. Pick a mirror line and the circle mirrors drawing 3 of Fig. There is no limit to the number of layers which can be set in a drawing. It is advisable to check the possibilities of settings available in the Options dialog and its sub-dialogs.
The DesignCenter palette appears on screen Fig. It can be moved around the screen by dragging with the cursor in its title bar. The DesignCenter tabs show the following features: Folder List — click the Folders tab and a list appears showing all the folders and the files they hold in the computer in use. Open Drawings — click the Open Drawings tab and a list of the drawings within a selected folder appears.
DC Online — click the DC Online tab and, depending upon how the computer is set up for the Internet, a dial-up connection window appears from which the Internet can be entered Fig. A click on Blocks in the directory shows icons of the symbols in that file.
Any one of the icons for the symbols can be dragged into the AutoCAD drawing area where they convert to a drawing of the symbol. The battery symbol is shown in Fig. First example — DesignCenter Fig. Select the directory in the Folders List. The drawings in the directory appear as icons in the preview part of the DesignCenter. Drag selected drawings for the icons into the drawing area. As each is dragged so the command line shows the prompts shown for the first example. Position and, if necessary, rotate each symbol as it is posi- tioned in the drawing area Fig.
Then click on Window in the menu bar and from the drop-down menu click Tile Vertically. The four drawings appear as shown in Fig. Click in each drawing window in turn and zoom to either Extents or All.
A click in any one of the windows makes that drawing the current one. When any object on screen is picked Fig. The properties of the dimension being much more numerous than those of the polyline, some scrolling of the lists is needed.
This can either be by scrolling the scroll bar on the left-hand side of the palette or clicking the double arrows against the list names. Some amendment of properties is possible within the palette. An example is shown in Fig. The new dimension number is entered in the Text override field and the dimension changes in the drawing. A click on Hidden2 changes the linetype of the ellipse from a Continuous to a Hidden2 type of line. The DesignCenter palette can be called from its icon in the Standard toolbar, by entering adcenter at the command line, or from the Tools drop-down menu.
The Properties palette can be called from its icon in the Standard toolbar, by entering properties at the command line or from the Tools drop-down menu. The Properties palette is of value for modifying objects in drawings on screen.
Call the Properties palette and modify the parts as indicated in Fig. Save each of your answers to file. If you have saved drawings from working the examples in this book or from answers to exercises, open four of these drawings. Then, using the Multiple Document Environment from the Windows drop-down menu, select Tile Vertically and note the result.
Isometric drawings. Orthographic projection Orthographic projection is a method of describing objects in technical drawings. The basic idea of this form of technical drawing is to show views of the object being described as seen from a variety of directions. Two methods of this form of projection are first angle projection and third angle projection. The object being described is placed in position in two planes, one horizontal, the other vertical, and crossing at right angles.
The object is viewed from its front and from above and, with the insertion of a sec- ond vertical plane, viewed from one side. The three viewing directions of the first angle projection are shown in Fig.
What is seen from these viewing directions is drawn on the horizontal and vertical planes. Per- spective is ignored. Vertical plane Look from this V. First angle Look from this direction Third to see the angle front view Fig.
Look from this Look from this direction to see direction to see the front view the end view Fig. The three planes are revolved so as to all lie in the same plane with the result that the views as drawn on the planes are seen as shown in Fig. The planes are regarded as being invisible and so are not seen in the result- ing first angle projection. Front view on End view on first vertical second vertical plane plane Plan on horizontal plane Fig.
Objects constructed from flat sheets require only a single view. Other objects may require two views. In general most objects can be described in three views, but more complicated objects may require a larger number of views.
In order to draw a view which shows the exact shape of the hole, a view at right angles to the sloping face is of value. Such an auxiliary view is shown in Fig. This view is in first angle projection.
Direction of viewing Fig. Plan on horizontal plane End view on Front view on second vertical first vertical plane plane Fig. In first angle projection a plan is drawn below the front view. In first angle projection end views are drawn on the opposite sides of the front view from which the view is seen. In third angle projection a plan is drawn above the front view. In third angle projection end views are drawn on the same side of the front view from which the view is seen.
In general, views are not labelled as such. In auxiliary views the projections are made onto an imaginary plane at right angles to the direction of viewing. This method can be carried over to drawings constructed using AutoCAD Lines can either be drawn using the Polyline tool when line widths are set as the tool is used, or using the Line tool with lines set to widths from the lineweight popup list Fig.
See also page noting the lineweight only takes effect when plotting or printing. Lines constructing using the Line tool can also be modified to any line width using the Pedit tool.
Lines described as Thin lines in Fig. In building drawings lines thicker than those shown in Fig. Types of technical drawings Outline line — 0. The third angle projection Fig. The first angle projection Fig. Isometric projection When constructing isometric drawings it must be remembered that this form of pictorial drawing is not a true 3D three-dimensional form of drawing see Chapters 16— Isometric drawings are constructed in a 2D screen.
Types of technical drawings Fig. Set Snap to Isometric. Toggle with F5 to Isoplane Right. Using the Polyline tool construct the outline given in Fig. The front view on the left of the isometric drawing given in Fig. Toggle to Isoplane Left and add lines from each corner of the outline as shown in the left-hand drawing of Fig.
Toggle back to Isoplane Right and add plines as shown in the right- hand drawing of Fig. With Copy Objects copy the isocircle downwards 20 units. With Trim, trim unwanted parts of the lower isocircle.
In Isoplane Right construct isocircles of radius 20 in both the upright parts of the drawing and copy them backwards by 20 units. With Trim, trim unwanted parts of these isocircles. The numbered items below refer to numbers against the iso- metric drawings Figs Dimensions of the drawings are taken from the drawing in Fig. R60 R50 10 10 10 50 80 R25 Fig. In Isoplane Left construct two isocircles. Draw a line through the diameters of the isocircles.
With Trim, trim the two isocircles into semi-isocircles. With Trim, trim the line. Add the end pieces as shown. With Copy, copy the upper semi-isocircle and the end pieces 50 units backwards. Trim unwanted parts and add lines to the end pieces as shown. In Isoplane Top construct two isocircles of radius 25 cen- tral to the end flanges as shown.
Trim away unwanted parts as shown. In Isoplane Right and with Copy Object copy the resulting semi- isocircles 10 units vertically downwards. Add vertical lines at the ends of the flanges and trim unwanted parts. Use the Osnap nearest to ensure the lines are in correct positions. In Isoplane Top add isocircles of radius 10 central to the end flanges. Copy the two isocircles 10 units downwards and trim unwanted parts. Repeat the stages 1—12 in the upside down position. Move the drawing stage 12 to its correct position in rela- tion to the upper part already drawn.
Some details will require to be trimmed away. Add the base of the stand. The isometric drawing is completed. Orthographic projections may be in first or third angle. In first angle, views are placed on the side of the front view away from the direction of viewing. In third angle, projection views are placed on the side of the front view nearest to the direction of viewing.
The vertical and horizontal planes on which views are placed are imag- inary. As many views are drawn in orthographic projection as are need to describe the object s being drawn as clearly as possible. Auxiliary views in orthographic projection are placed on imaginary planes at angles other than vertical or horizontal.
Isometric projection is a 2D pictorial method of describing objects. Construct a full size three-view third angle projection of the stand. Do not include any of the dimen- sions.
Include suitable borderlines and title block with your drawing. Construct a full size isometric drawing of the stand. Or in case you previously pin point a particular topic, you should use the Glossary page to simply find the topic you are interested in, considering that it assemble alphabetically. According to our checklist, this document is published on 25 Jul, , documented under serial number of --, having file size about Much of our digital book repository carries a significant selection of digital books plus Pdf document selection coming from many different topics and area of interest.
From owners manual guidebook for all kinds of products and electronics from numerous model as well as costly university book, college paper from many different topic for your research project. We hope one of the documents on the related list might be meet to your demand and prerequisite. Millions discover their favorite reads on issuu every month.
0コメント