Blocks

Blocks
A block in Autocad is a collection of all of the line and arc entities that create an object, 'moulded' together to make one selectable object. Selecting one particular entity (such as a midpoint of a line for example) will select all objects contained within the block. They can be moved, rotated, mirrored etc and will always be treated by Autocad as one whole object.The only way to 'break' the block apart, and split it into its seperate line entities, is to explode it. If one particular part of a block needs to be changed, the block has to be exploded, the modification made, and the objects created back into a block.

Why use Blocks?
Blocks are an invaluable way of quickly arranging complex pieces of a drawing. Selecting the object is a breeze, it is no longer neccessary to painstakingly select each indivdual line. They also prevent accidental modification of parts of the object, as they cannot be modified unless the whole block has been exploded. Blocks also make it easy to duplicate the same object throughout a drawing, and as Autocad recognises that each copy of a block is identical to the previous, the memory & processing time required byAutocad is reduced.The most impressive feature of blocks is that if a block detail has to be amended, simply changing the detail and 'redefining' the block applies the changes to EVERY instance of the block in the drawing!

Autocad Object Snap

Object Snap

Object Snap tools are available from the Object Snap toolbar ( View - Toolbars to enable). They allow for precise drawing within Autocad. For example, a rectangle could be drawn from the exact endpoint of an existing line by simply selecting the 'Snap to Endpoint' tool, or we could draw a line from the centrepoint of a circle using the 'Snap to Center' tool. In many cases, object snap avoids the need to draw construction lines, thus making it quicker and easier to create precise, accurate drawings.

The first point of the Rectangle above was drawn from the Endpoint of the 45 degree line.
The object snap tools can be used whenever a point has to be defined, which is in nearly every drawing command used! When we use the snap tools, a yellow marker will appear when the cursor is near a suitable snap point. A single left click of the mouse will automatically select the marked point.

Snap Tools
From left to right on the above toolbar screen shot (Note: Dependant on your version of Autocad, some snap settings may not be available).
Snap to Endpoint - This will select the endpoint of any line or polyline segment. Also works on 'closed' objects such as rectangles.
Snap to Midpoint - Very handy tool. This will select the mid-point of any line segment.
Snap to Intersection - Selects the exact point at which two lines cross.
Snap to Apparent Intersection - Similar to above, although the lines don't have to intersect. This snap requires you to select a line, then hover the cursor over any other line, the marker will let you select the point where the two lines would intersect if they were extended.
Snap to Extension - This snap tool enables you to select a point along the same orientation as an existing line, with a handy readout of the angle and position of the point (See screen shot below).
Snap to Center - This handy snap function selects the perfect centre of an existing circle. Even more impressive however is that the centurion of an arc or semi-circle can also be selected.
Snap to Quadrant - Snap to the four quadrant points of a circle (Top, bottom, left and right).
Snap to Tangent - As it says, snaps to the tangent point of an arc.
Snap to Perpendicular - Snaps to the the perpendicular point on an object from the original start point. Pretty straightforward, and very useful.
Snap to Parallel - Snaps parallel to a specified line.
Snap to Insert - Snaps to the insert point of an object, such as an inserted block. Not really that useful.
Snap to Node - Snaps to points drawn using the POINT command.
Snap to Nearest - Should be called snap to anything! Quite literally will snap to anywhere along any length of any object. Can be useful though while 'sketching' with Autocad, or perhaps laying down a few construction lines.
Object snap settings - Snap settings.
Object snap can be toggled to be permanently on or off via the OSNAP tab situated to the bottom of the CAD window above the Windows start menu. Alternatively simply press F3 to toggle.
To change which snap functions are to be used, either right click the OSNAP tab and select 'settings', or select the object snap settings button from the Object Snap toolbar.

Autocad Hatching

Hatching is used to add shaded patterns to objects and shapes within an Autocad drawing. Hatch patterns can be used to indicate a material to be used, such as a concrete hatch. Alternatively it could be used to make an area of a drawing stand out.

A foundation detail with the Autocad default AR-CONC hatch pattern applied.

The hatch command can be found on the draw toolbar, or the draw drop down menu. When entered, a dialogue box appears as shown below:

Type - Custom hatch patterns can be created in Autocad. Leave it set to predefined to use Autocad's built in hatch patterns.
Pattern - This is where we select a hatch pattern from Autocad's default list. Select to view more patterns. The hatch pattern palette appears, with hatch patterns arranged under the categories: ;ANSI', 'ISO', 'Other Predefined' and 'Custom'. The most common hatch patterns required are under the 'Other Predefined' Tab.
Angle - This sets the angle of the hatch pattern, the default value is 0.
Scale - This sets the size of the hatch pattern. This must be set correctly dependant on if you are drawing in metres or millimetres. A little trial and error is required to obtain a suitable scale (See Preview below).
Pick Points & Select Objects - These are Autocad's two different methods of hatching an area. Using pick point, clicking inside an area (such as a rectangle) will result in the hatch pattern being applied to all blank space within the boundary. Select object simply hatches within a selected object.Great care must be taken to ensure that the area to be hatched is closed, and all line endpoints are meeting each other. If a small gap is left open, the hatch command will fail, usually with the error: Unable to hatch boundary.
Preview - Enables a quick preview of the hatch before applying it, letting us quickly change and preview settings before we ok them. Very useful when trying different hatch scales.
Inherit Properties - This command enables the hatch settings of a hatch already in use in the drawing to be brought into the boundary hatch dialogue box.
Composition - This is how Autocad is to treat objects to be hatched. For the moment, leave it set to Associative.

Pick Point

The above hatch was created by using the pick point method. The hatch stays within all the solid lines.
Select Object The above hatch was created by using the select object command. The rectangle was selected, and as a result all of the rectangle becomes hatched. Interestingly, if both the hexagon and rectangle were selected (i.e BOTH boundaries) then the hatch pattern would have had the same result as in the above 'pick point' example

Be careful to ensure that there are no gaps in the boundary to be selected (zoom in if required). Usually, this results in either unexpected results, or a hatch error as shown below.

Have a go with the hatch command with the following Autocad drawing file:

Use the select object method to apply the hatch pattern AR-CONC (found in Other Predefined in the hatch pattern palette) to the concrete foundation. Use a hatch scale of 1 and angle 0.

Use the pick point pattern to apply the hatch pattern ANSI32 (Found in ANSI in the hatch pattern palette) to the bricks. Use a hatch scale of 3 and an angle of 0. Note:separate multiple areas can be selected with the pick point method, all in one go!

Your finished drawing should look like the one below:

Autocad Text

Text can be added to an Autocad drawing to create notes and labels on your drawings. There are two different text commands used to add text to drawings: Text and Mtext.

The text command is a simple way to add basic text notes. The height and rotation of the text can be quickly specified and the text can be viewed on the drawing while being typed.

Try adding a small piece of text in a new drawing using the text command:

1) Enter the command text into the command console then hit return

2) When prompted for a start point, select somewhere in the screen just left of centre

3) When asked for a height, enter 3

4) When asked for a rotation angle, hit enter to accept the default of 0.

5) Now simply enter your text. Type: Autocad Central then hit return to start a new lineType: Lesson 8

6) Hit return twice to exit the text command.

The text should be on two separate lines as shown below:

Try selecting the text. Notice how each line is separately selectable and independent of the previous line? Although the text command is simple to use, as each line is separately editable, modifying notes on a drawing can become a nightmare! This text type is called single line text.

Multiline Text

Multiline text is the more advanced text tool within Autocad. It can be chosen from the 'draw' toolbar by this icon: . The multiline text command has its own editor, with all the options available that you'd expect to see in a word processing program. Also, all text on separate lines is treated together, so editing notes and sentences is simple.

1) Select the multiline command button

2) We are prompted to select a first corner then second corner. This invisible boundary sets the horizontal extent of the text. When text is entered into the multiline text editor, it will automatically start a second line when it comes to the edge of the text box we specified. Similar to getting to the right hand margin in a text editor. Select a box roughly a quarter of the drawing area.

3) The Multiline Text Editor then appears:

The main character tab of the text editor box is where we choose the font style, text height, colour and also add symbols such as diameter or degrees symbols.

The Properties tab is where we can change the text rotation and paragraph justification settings.

Change the text style to 'Arial'

4) Set text height to 3

5) Enter the following text into the text editor window: Autocad Central

6) Hit enter for a new line, then enter: Lesson 8

7) Press the ok button to place the text into the drawing (The text placement will be justified as set in the properties-justification setting in the text editor, relative to the text area box we selected in step 1)

Notice how when the text is selected, it is treated as one entity rather than separate lines? This makes it much easier and quicker to edit. To edit the text in the drawing area, simply double click the text with the cursor to open up the text editor.

Text in Autocad is treated like every other object, it can be rotated, mirrored, exploded, moved layers etc.

When setting the text height, it is important to remember that it is relative to the units you are using. For example, if you decide that 1 Autocad unit is equal to a metre, then setting a text height of 3 would result in 3m high text, and would tower over the drawing! A text size of somewhere around 0.02 would probably be more appropriate. When first using text, a small amount of trial and error is required to get the text height to a suitable size. Try to aim for a text height which measures between 2 and 3mm in paperspace for general notes.

Layers

Layers are a way of managing, tidying and also controlling the visual layout of a drawing. A whole section of a drawing can be turned on or off, or simply one aspect can be controlled - text for example. This is all done by using layers within Autocad

The concept of layers is used in other software applications, such as Paintshop programs. For those not aware of the concept, we'll start from the beginning:

When a new Autocad drawing is created, everything which is drawn is drawn on the one default layer, named 0. When creating drawings, the layer 0 shouldn't really be used. New layers should be set up with names corresponding to the content contained on them.

What is a layer?

A layer can be thought of as a large piece of clear plastic, as infinitely large as the drawing area in Autocad. When drawing in Autocad, everything is drawn on the default layer which is set current. Only the objects you are drawing are visible on the layer, the layer itself can never be seen - it is invisible. Each new layer is created by you, the user .Normally, it is acceptable to have a layer for each different part of a drawing. The layers created for a simple house plan could be as follows:

Wall_External

Wall_Internal

DoorsWindows

Fittings

Text_Notes

Dimensions

The separate lines and shapes representing each part of the house would be arranged on its relevant layer above. Each layer could be assigned its own colour so that everything drawn on that layer appeared the same colour.

Remember we said that layers can be used to manage drawings? well for example, in order to see the drawing more clearly, we may want to remove all the text and dimensions from the drawing. We want to keep the information, just remove it from view. Deleting it wouldn't be appropriate as we would lose all of our work! All we have to do is tell Autocad to not display the Text_Notes and Dimensions layers by turning off the layers in layer manager. The layers can then ne turned back on again whenever we choose.

Layers are controlled by the layer properties manager button which is located on the object properties toolbar:

The layer property manager is where all the layers are controlled. The layout above shows a typical use of layers.

From the layer property manager we can:

Add a New Layer - Press the New button to create a new layer.

Delete a Layer - Press the delete button to delete the selected layer.

Set Current layer - Press the current button to set the selected layer current. All objects drawn will then be drawn on this current layer.

Show Details - Press the show details button to see more detailed information about the selected layer.

Each layer also has the following options against it:

Each layer also has the following options against it:

Name - Displays the layer name.

On - Controls if the layer is on or off. Select the light bulb to turn the layer off on the drawing.

Freeze in all VP - Pressing this will freeze the layer in all viewports as well as the current model view (see lesson 10 to learn about viewports)

Lock - This handy feature locks a layer preventing any content of the layer from being modified.

Colour - Change this to whichever colour you like. All objects drawn on the layer will display the chosen colour provided that the objects colour setting in the object properties toolbar (shown above) is set to 'By Layer'.

Linetype - Set the default linetype for all objects drawn on the layer. i.e continuous, dashed, dotted etc.

Lineweight - Set the thickness a line appears .Default is no thickness. This option can be toggled on/off on the display by the LWT button above the command console.

Plot - Select if the layer will be shown when the drawing is plotted (printed).

The current layer, layer colour, linetype and lineweight can all be controlled outside of the layer properties manager via the object properties toolbar.

That's it for basic layer controls! Get used to using layers as you will be using them often - especially when you find you need to start managing large drawing files that contain a lot of information.

Modify Commands(2)

Move - The move command works exactly the same as the copy command described above, except instead 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) Select the rotate button from the modify toolbar.

2) Select the vertical line and circle.

3) Select the base point for the rotation. This is the point which the selected objects will be rotated about. Select the bottom end of the vertical line.

4) Autocad asks for a rotation angle. Note how mouse movements rotate the object in real time enabling quick rotations to be made. We will specify an angle of 45°. Enter 45 and hit enter.

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 a selected 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 command operates.

Stretch - The stretch command will stretch a selected part of an object, and can be used to lengthen or shorten a particular object.

Looking at the stretch command introduces two very different ways of selecting objects. So far you have probably been 'picking' an element of a drawing with one single click of the mouse while the cursor is over the 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 window drawing a box from top left to bottom right will select all objects FULLY within the window. Drawing a window with a box from bottom right corner to top left will result in all objects being selected that ANY part of the window passes through.

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 partially within the window does not get selected.

The selection window shown green above (Note how the different window selection type is shown as dotted) 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) Select the stretch command button

2) Use the bottom right to top left window type to draw a dotted window around the end of the object as shown below:

3) AutoCAD asks for a base point, select around where the line and circle meet.

4) Notice how where we move the mouse the object is becoming stretched. We can simply select a point with 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 lengthen the line by, when the line is selected it will then be lengthened by the specified distance ONLY to the side of the line where the line was selected. i.e If when you selected the line, you selected it just to the left of centre, then the left side of the line would be lengthened.
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 the percentage 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 will adjust the lines length to the distance specified.
DY - Dynamic: Autocad adjusts the length of the line as the mouse is moved in the direction the line is to be lengthened. This is not an accurate technique, although is useful for quickly lengthening construction lines for example.

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

The protruding yellow lines on the image on the left have been trimmed to the edge of the rectangle as shown 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 'cutting edge' and not the object to be trimmed.

i.e the cutting edge in the above example was the rectangle, the vertical and horizontal lines were trimmed to this edge

Trim Tutorial

1) Open the above tutorial file into Autocad. Choose the trim command

2) When asked to select object we need to select the object(s) which will be the cutting edge! In this case it is the rectangle so select it and hit enter.

3) Select all 4 of the ends of the yellow lines OUTSIDE of the rectangle. Notice how they are removed as we select them

4) Hit enter to end the trim command.

Just remember, be aware what is your cutting edge! The trim command can be used on most objects within Autocad. One common mistake beginners make is that they can't understand why Autocad refuses to trim a circle to a single line which intersects the circle at one point only. If the circle were to be trimmed to 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 a selected line to a point of intersection of another selected object. In order to successfully use the command, you have to make sure that when the line is extended it will actually intersect the object selected which the line is to extend to!

Break - The break command is identical to the above break at point command, except the break line isn't as 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 is best shown with the example below:
The rectangle on the left is 50mmx50mm. The rectangle on the right has been chamfered by a distance of 5mm.

1) Draw a rectangle using the line command (NOT rectangle - we will see later) at a size of 50mm x 50mm.

2) Select the chamfer button

3) We are going to chamfer the 50x50 rectangle by a distance of 5mm (as seen above). Enter D for distance then hit return.

4) Autocad asks for the first chamfer distance. Enter 5 then enter.

5) Autocad then asks for the second chamfer distance. In this case we are using the same chamfer distance, although Autocad can draw a chamfer with two separate distances. As we want the same distance, input 5 then enter.
We now need to select the two lines to chamfer. This would be the two intersecting lines we wish to chamfer.

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 procedure to chamfer the remaining 3 corners.

You may have wondered why we drew the rectangle using the line command instead of the much quicker rectangle command. This is because the rectangle command draws the rectangle in the same manner as a polyline. We can't select the individual lines forming the rectangle, so we can't select the separate lines we wanted to chamfer. There is however a way to chamfer two polyine segments:

1) Draw a rectangle with dimensions 50x50.

2) Select the chamfer button , and this time enter P for polyline.

3) Autocad asks for a 2D polyline, select the rectangle we drew.

Autocad automatically chamfers each intersecting line segment of the polyline to the last specified chamfer 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 chamfer distance, when prompted to select an object simply hit return until out of the chamfer command. Your new chamfer 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 a straight 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 rather than a distance. We'll go through the process just incase you're unsure:

1) Draw a Rectangle using the line command, with a size of 50x50.

2) Select the fillet button

3) We will specify a radius, so enter R for radius

4) Autocad asks for the fillet radius, enter 5 then hit enter
The fillet radius is now set.

5) Select the first line segment to fillet then hit enter

6) Select the second line segment to fillet then hit enter

The two lines will have been filleted with a radius of 5 as we specified. Repeat the procedure to fillet the remaining 3 corners

As with the chamfer lesson above, we can apply the fillet command to a polyline which will fillet all intersecting 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 to its basic line entities.

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

rectangle can't be selected or edited. If we choose the explode button , then select the rectangle 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 an object, 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 should be able to create most 2D drawings you would ever need too! (Of course - combined with the basic draw tools covered earlier).

Modify Commands(1)

Basic Modify Commands

Here we'll cover the modify tools, which give us control over simple shapes we have created. As the name 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 at point, 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 by the user, without affecting the original elements.

1)Select the copy button, then select the object(s) to copy then hit return (or right click)

2) Select the base point where to copy from (For example if copying a circle, it would be sensible for the base point to be the centre of the circle)

3)Enter the second point of displacement - this is where the new base point of the copied objects is to be positioned. Note that the base point is not visible, just a co-ordinate in Autocad's drawing system to enable accurate positioning of objects where required.

When quickly copying an object it is quite acceptable to simply pick a rough point to copy and then position an object without specifying co-ordinates, it can then be accurately positioned in the drawing area using the move command.

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

Mirror Tutor

1) Open the drawing file. It should look like the one shown below:

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

3) Select the 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 the command line to enable Autocad's Ortho function, which limits the available pointer selection points to horizontal or vertical positions relative to the first point selected. Ortho can be used with all commands.

6) Autocad now asks if we want to delete 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 a mirrored copy of the original object, without the original object. In this case we want to keep the original object to complete the drawing. Enter N for no followed by enter.

You should now have a simple drawing of a wine glass as below.

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

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

1) Create a new drawing and draw a rectangle from a base point of co-ordinates 10,10 at a size 50,50.

2) Select the offset command

3) When prompted for an offset distance, enter 10 .

4) When asked to select an object, select the rectangle we drew.

5) Autocad then asks for a side to offset. If we select a point outside of the rectangle then a new rectangle will be created outside of the original at a 10mm offset. Selecting a point within the rectangle would create a rectangle within the existing rectangle at a 10mm offset.

Select a point outside of 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 wine glass 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. The array 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 at specified spacings. A polar array would create copies of an object in a circular pattern based on a specified centre point.Shown below are the two types of array. The red objects are the original objects, and the yellow are the copies created with the array.

Rectangular Array

1) Open the Autocad file, select the array button

2) Select 'rectangular array'

3) For select object, select the chair

4) For the rows and columns, we will select 5 each time. This tells Autocad to repeat the object 5 times horizontally and 5 times vertically.

5) For column offset and row offset enter 1000

6) Autocad 2000,2002 users select the OK button.

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

Polar Array

1) Open the Autocad file, select the array button

2) Select 'polar array'

3) For select object, select the entire drawing (the circle and vertical line)

4) For centre point, choose the bottom end of the vertical line. This is the point where the copies of the original object will be rotated about

5) For number of items, enter 12.
6) For angle to fill, enter 360.

(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:

Polylines

Polylines

Polylines draw lines similar to the line command we used in lesson 2, but are a lot more powerful. Let's start by drawing the same plot of land we drew in lesson 2, but this type using polylines. The polyline command is situated on the 'draw' toolbar.

1) Choose the polyline command

2) For a start point, enter 50,50

3) Now enter the next line end points:

@25,0

@0,40

@-25,0

c

Right click or hit enter to end the polyline command.

4) Try selecting any part of the area we just drew with one click of the left mouse. The lines will become dotted to show that you have selected the polyline.

You will notice that although we entered each line end point command separately, because we drew the area with the polyline command left open, AutoCAD treats the polyline as one entity regardless of the shape or direction of the lines.

See the blue squares at each corner of the drawing?, these represent each line point specified when we drew the polyine. They are also a handy quick editing tool to adjust the shape of our drawing. Try left clicking on one of the blue squares with the centre of your crosshair, the corner follows your mouse movements. Left click to reposition the corner where your crosshair is, or press the Escape key to let go. These blue squares are called Grips.

Try using the grips to dramatically alter the shape of your land layout.(TIP- to undo any changes you make, simply select Undo from the edit drop down menu as often as required)

Advanced Polylines - Arcs

There is more to polylines than just grips, a polyline can actually be any shape or thickness. Now we'll have a play with some more interesting Polyline features.

1) Undo any changes you made to the rectangular land layout we drew, and zoom extents to be left with the layout as shown above.

2) Select the polyline command. Notice the command line is asking for a start point, choose somewhere central within the upper area of our plot of land.

3) AutoCAD now asks for a next point or we can choose further drawing options:

The options are: Arc, Halfwidth, Length,Undo,Width. To select which option we require, enter the letter from the command we require that is in UPPER case (Which is most often, but not always, the first letter of the word).


4) We are going to draw a pond on the land, so enter A for Arc.


5) Notice how the line becomes arced instantly? Select a few points and close the polyline to get something similar to the drawing shown below.

Note: when you enter 'c' for close, AutoCAD will ask you to clarify you want to use the close command and not centre (as they both begin with c). Enter CL for close which are the two upper case characters).

The arc command is obviously not just for drawing free-hand ponds! We can enter further commands within the arc command by using their upper case letters to have more control over the arc, such as specifying a radius.

Have a play with the arc command and get familiar with how it functions.

Advanced Polylines - Width

1) Now we'll draw a fence around the pond. Select the polyline command again, select a point close to the edge of the pond to begin the polyline.
2) Press W to activate the polyline width command. By default the polyline width command is set to 0. Autocad asks for a width for the start of the line, enter 0.1 then hit enter. AutoCAD now asks for the width for the end of the line, as we want it to be the same thickness, enter 0.1 again. Now just try drawing a free hand fence around the pond.

The thickness command is very useful, the more that you use AutoCAD the more reasons you'll find to use it!

Try drawing a new polyline with a starting width of 0, and an ending width of 1. A handy arrowhead pointer?

Thats about it for polylines! They may not seem so great just yet, but when we start using modify commands you'll see just how useful it is to be able to manipulate and select a whole complex shape in one go rather than selecting all the separate entities.

Drawing Limits

Drawing Limits

In the previous tutorial, drawing limits were mentioned while explaining the use of the zoom all command. When the zoom all command is chosen, AutoCAD zooms to the extent of the user defined limits. Limits can be thought of as the extent of the drawing area. The AutoCAD drawing area is, in theory, infinite. As long as you continue to draw, AutoCAD will continue to give you the drawing space.

If thought of in practical terms, if we were to manually pencil draw a 1:1 scale (full size) drawing of a wrist watch, why draw it on an A0 sized sheet of paper when A4 size is adequate? AutoCAD drawing limits follow the same logic. We can tell AutoCAD the drawing space we require (although we have the option to increase this if we so desire at a later stage).

AutoCAD will display a grid to the extent of the drawing limits specified.

Lets have a go:

1) Start a new AutoCAD drawing.

2) Start the line command

3) For the start point , enter 0.2,0.2 For the next point enter @0,0.52

4) For the next point enter @0.37,0

5) For the next point enter @0,-0.52

6) To close the box, we'll try a new technique. Normally, we would now enter @-0.37,0 to draw a horizontal line back to the start position to close the box. As we have drawn all 3 lines keeping the line command open, there is a quicker way to draw the box. Type the letter c in the command line (the c stands for close) to draw a line from the current location back to the start point.

Your screen should be similar to the screen shown below (You may have to zoom extents to see the entire drawing).

7) Now try using the zoom all command. The drawing will be barely visible (if at all). This is because the default limits are not set correctly for our drawing. We need to enter new drawing limits.

8) Type limits directly into AutoCAD's command line. You will be asked to specify the lower left co-ordinates (remember - in relation to the UCS). Hit enter to accept the default value of 0.0000,0.0000.

9) AutoCAD now wants us to specify the upper right limit co-ordinates. There is no right or wrong value, but it should be set to a sensible value for the drawing size. Our drawing is only 0.52m x 0.37m. Lets enter an upper limit of say, 1m,1m from the UCS. Enter 1,1 into the command line and hit enter.

10) Now try the zoom all command again. The view should be much closer as it is set to the drawing limits.

Some professional AutoCAD users manage to go their whole careers without ever altering AutoCAD's limit setting, and quite frankly:- it's easily done! There will be many times (especially if like me, you never use the zoom all command and grid!) that adjusting AutoCAD's default limit settings has no advantage.Why mention it then? well... occasionally while panning your pan icon may gain a line next to it (dependant on the pan direction) and you can't pan any further. This is because the limits have been reached and AutoCAD refuses to let you see beyond your defined drawing areas. You may then require to enter the limits command and change the default setting.

Try panning away from the drawing we just made, as soon as you hit the 1m drawing limit we set, we can't pan any further.

Just in case you were curious, the drawing is of a DVD case (520mmx370mm). If we were to have drawn the case in millimetres instead of metres (i.e we decide one AutoCAD unit shall equal 1mm instead of 1m - perfectly acceptable to do) then a much larger upper right drawing limit would have been required, perhaps 1000,1000.

That's about all there is to know about drawing limits!