AutoCad - Layers, Colours, Linetypes, and Template Drawing.

 Layers

 Most CAD systems have some kind of overlay concept. AutoCad uses layers. Layers are used to separate and structure drawings; layers can be turned on and off and can have various types of lines which are associated with them.

 Layers make us possible to manage , to tidy up and also control the visual layout of the drawing. This concept have been used in any other programs such as Paintshop. So to give more understanding let us start with the basics.

 When we start AutoCad every drawing is drawn on the default layer which is labelled as 0. If we want to create a drawing , we shouldn't use the layer 0 but we have to set up a new layer with names corresponding to our drawing.

 To make it more understandable we have to imagine a layer as a large piece of clear plastic , which is the drawing area in AutoCad. At first everything is drawn on the default layer which is set current. We can only see the drawing but not the layer. Each new layer is set by us depend on the drawing. It is a common practice to have different layer for different part of drawing. The eample of the usings for a simple building :

• wall
• floor
• outer_wall
• etc....

Different layers and shapes would be arranged according to their layers. For each layer could be assigned its own colour so that everything on the same layer would appear in the same colour. Layers can be used to manage a drawing. The best example is when we want to see a drawing more clearly by removing the all the text and dimensions from the drawing. It is not a good idea to delete all the text and dimensions therefore the best way is by turning off that particular layer in layer manager. The layer can be turned back on again whenever we want. 

Layers can be managed in Layers properties manager. Here we can manage the new layer , the name of the layer , to turn on and off the layer , freezing function , colour , linetype , lineweight and plot. 

Creating new layer .

Open the Layers Properties Manager by clicking the icon at the object properties toolbar. Press "New" button to create nw layer.

Assigning colour to layer.

Click the colour icon and change the colour according to our taste. All objects drawn on the layer will display the chosen colour provided that the objects colour setting in the object properties toolbar is set to "By Layer".

Assigning linetypes and lineweight.

We can set the linetypes of the objects drawn . i.e dot, dashed, continous. We can also set the lineweight of the line i.e the thickness. This option can be switched on/off on the display by the button at the command console.

Changing the current layers

We have to press the current button to set the selected layer current. All objects will be drawn on this curent layer.

Editing corners using FILLET and CHAMFER.

Fillet

The fillet command will create a radius between 2 points. It extends two lines until they meet, inserts a curve where the line joins.

How to do this ? We have to click the Fillet icon then we need to specify the radius of the curve. After that just select the first and second line segment that we want to fillet. One thing that we have to remember not to specify too large radius.

Chamfer

The chamfer command will chamfer the intersection of 2 lines to a specified distance. To perform this command just click the chamfer button and enter D to key in the distance of chamfer.Then select the first line after that select the 2nd line . 

This method is not applicable for rectangle as rectangle is assumed as polyline. So during after clicking chamfer button enter P for polyline then select 2D polyline. Press and chamfer will applied to all corners of rectangles.

 To join 2 separate lines just use the chamfer command with distance 0.

Zooming window , previous and all

 It is really difficult to look or to adjust the drawing if the drawing is too small so that is where zoom function come in handy. We can change the magnification of a view by zooming in and out, same as the camera where we can zoom in or out using camera. With zooming function it doesn't mean that we change the size of the object but actually we just change the magnification of the view.

Zoom Window

We  can actually quickly zoom on a rectangular area of our drawing by specifying two diagonal corners of the area you are interested in. This is where zoom window is applicable.

The lower-left corner of the area we specify becomes the lower-left corner of the new display. 

How to do that ? Just type Z and W then we have to specify the first corner and the second corner which is the opposite point.

Or we can just click the zoom window icon at the toolbars panel.

Zoom Previous

When we work with minute parts in our drawing, we may need to zoom out frequently to see an overview of our work. Use ZOOM Previous to return quickly to the prior view. 

Zoom previous make our life easier whereby AutoCad can store up to 10 views. Just enter Z and P then we will be brought to the previous view.

Zoom All

Zoom All is used to view the whole drawing even the drawing is out of the grid limits i.e current extents. To use zoom all enter z a or click the icon of zoom all which can be found at toolbar menu.

Using Realtime Zoom , Pan and Plot preview.

Realtime Zoom

Realtime zoom is used as we want to zoom the drawing to a logical extent. Right click on the screen and select the shortcut menu zoom. The cursor will change to a magnifying glass with plus and minus sign. 

If we right click the cursor then a few menu will come out for us to select i.e pan , zoom , ext and etc. 

We can use this zoom function by holding down the right button of the mouse and move the cursor upward to zoom in and move the cursor downward to move downward.

When we have reached the zoom-in limit, the plus sign in the cursor disappears, indicating that we can no longer zoom in. When we have reached the zoom-out limit, the minus sign in the cursor disappears, indicating that we can no longer zoom out.

When we release the pick button, zooming stops. We can release the pick button, move the cursor to another location in the drawing, and then press the pick button again and continue to zoom the display from that location.

To exit zooming at the new position, press ENTER or ESC.

Pan

Pan is important for us to reposition the view in the drawing area or zoom to change magnification.

With the realtime option we can dynamically pan the drawing by moving the cursor. But it can't change the location and magnification of objects in the drawing . It change only the view of the drawing.

Plot

Plot is a method where we want to transfer the drawing of AutoCad by using plotter , printer or file. How to do plotting ? Just click the Print icon or we can just simply type plot in the command box. And to proceed we need to follow the setting or else we can also change the setting for their uses.

Setting Limit

The grid is a rectangular pattern of dots or lines that extends over the area you specify as the grid limits. Using the grid is similar to placing a sheet of grid paper under a drawing. The grid helps you align objects and visualize the distances between them. The grid is not plotted.

To set the limit just click the drop down menu Format -> Drawing Limit. Then we have to specify the lower left corner or we can just switch on the limit or just press enter.

What does it mean by turn on? When it is turned on limits will be checked therefore we cant enter any point outside the grid limit. But bear in mind that it check only the point that we enter rather than the drawing which is extended outside the grid limits.

When the checking is turned off it will maintain the current values for the next time the checking is on.

Using the MOVE, COPY

This one is simpler. To move the object in the drawing just select the object and hold the select button at the same time move the cursor to the new position.

Object can be copied by selecting the object and click copy icon or right click and select copy command and another method is by typing command copy and select the object. After that select the base point or the displacement point for the new position.

Trim

We can shorten or lengthen objects to meet the edges of other objects.

This means we can first create an object such as a line and then later adjust it to fit exactly between other objects.

Objects we select as cutting edges or boundary edges are not required to intersect the object being trimmed. We can trim or extend an object to a projected edge or to an extrapolated intersection; that is, where the objects would intersect if they were extended.

If we do not specify a boundary and press ENTER at the Select Objects prompt, all displayed objects become potential boundaries.

To select cutting edges or boundary edges that include blocks, you can use only the single selection, Crossing, Fence, and Select All options.

Scaling Object

If we draw and plot from model space, we must determine and apply a scale factor to annotate objects before we plot.

We can draw and plot entirely from model space. This method is useful primarily for two-dimensional drawings that have a single view. With this method, we use the following process:

• We have to determine the unit of measurement (drawing units) for the drawing.e.g if we want to draw a map and we will decide one unit equal to one kilometer.
• We have to specify the display style for the drawing unit such as the unit type and precision. e.g a value of 14.5 can be written as 14.500 or 14 1/2.
• We have to calculate and set the scale for dimensions, annotations and blocks. This is very important to ensure that they are at the correct size when we plto the final drawing. The things which have to be taken care are text , dimensions, linetypes, hatch patterns and blocks.
  
• We have to draw at full scale (1:1) in model space.
  
• We have to create the annotation and insert the blocks in model space.
  
• We have to plot the drawing at the predetermined scale.
  

To begin the process we have to start the SCALE command. We have to draw a window around the new set of objects to select objects and press . Then we have to select base point which is normally at the bottom left corner of the border. After that we have to enter the the scale factor e.g 2.