Chapter 8: Paper Space and Model Space – Machine Drawing with AutoCAD

Chapter 8

Paper Space and Model Space

Chapter Outline

 

In case of manual drawing, one of the major objectives of the draftsman is to organise the different projection views of a component or a group of components in the available area of the drawing sheet. Sometimes, in addition to the usual views, an enlarged view of a particular portion of the component may be required to be shown on the drawing sheet to clarify a minute detail of that portion. In such situations, it may be essential to incorporate more than one scale in the same drawing sheet. In AutoCAD, you have so far drawn in the model space environment as this is the default option provided by the software. In addition, you have looked at the drawing using single view and single scale. However, in actual practice, not only do you have to organise the layout of the entire drawing well, but also need to use more than one scale. This can be achieved efficiently with the help of the paper space option provided by AutoCAD from release 12 onwards. Using this mode, it is also possible to combine drawings with different scales and plot them on a single sheet. For example, the overall plan of one floor along with one enlarged view of a typical unit can be pasted on a single sheet for subsequent plotting.

Apart from the above fact, the greatest advantage of paper space mode can be explored if the component(s) is developed using 3-D solids, the recent trend being practised in industry. A component created in solid model may eliminate the process of expensive prototype development, thus making the product development cycle shorter. It also becomes the core of the manufacturing process as CNC machine code can be directly generated based on the solid model developed in AutoCAD. In addition, it is not necessary to draw the orthographic projection view separately. Rather, you can simply look at the solid from different directions (view points) and create the projection views on different viewports. With the introduction of paper space features, it is possible to separate the design and construction of a two-three-dimensional model from its plotting. Thus you can create a two-three-dimensional model in model space (the default AutoCAD mode) and then use paper space mode to plot the drawing. Furthermore, you can arrange several viewports (with different scales) on paper space so that they can be plotted together.

When it comes to drawing display and arrangement, there exist two distinct groups of CAD operators-those who have used paper space and would never use anything else and those who have not used paper space, generally due to lack of training.

This chapter will familiarise you with the wonders of paper space and viewports so that you may join the ranks of enlightened operators. To keep it simple, we shall confine ourself to the two-dimensional environment throughout this chapter. We will venture into the 3-D world later to discover the benefits of using paper space.

VIEWPORTS

Viewport is a very important concept in AutoCAD. Viewports can be created from both model space mode and paper space mode.

If you try to look at an object placed in the center of a room through different windows or from the top or bottom of the room, you will have an idea of what viewports are. They are basically openings into your drawing and by looking through them, different views of the same object (s) can be seen.

In AutoCAD, two types of viewports can be created: 1) Tile viewport and 2) Floating viewports.

A clear understanding of these two types of viewports and their usage is required to understand paper space environment thoroughly.

Tiled Viewport

Tiled viewports can be created in model space using the Viewports dialog box as shown in Fig. 8.1. The dialog box appears on the screen when the Viewport (Vport) command is invoked. The name ‘Tile viewport’ reminds us about the floor tiles of a room. Therefore, tile viewport cannot overlap one another. Some of the important features of tile viewports are listed below.

 

FIG. 8.1   Viewports dialog box

 

  1. They are rectangular in shape.
  2. Only one viewport is active at a time.
  3. A change incorporated in any viewport will affect the other viewports as well.
  4. Plot can be taken from the active viewport only.
  5. Tiled viewports are not objects.

Creating Tiled Viewports in Model Space—An Example

Let us show by an example how to create more than one tiled viewports on the screen to facilitate the placing of different portions of the drawing in different viewports. Only the command and its brief explanations/steps are given here.

We shall start with the drawing of a pulley created in AutoCAD and is shown in Fig. 8.2. Make sure that you are in model space before beginning on the commands. You can check this off from the toggle key marked Model (or Paper) on the Status bar. If Model is highlighted, you are in the model space of AutoCAD. Let us now create three viewports using the following commands.

 

FIG. 8.2   A pulley created in AutoCAD

 

 

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Vport ↵ Activates the Viewports command to display the view-ports dialog box (Fig. 8.1).
Select the Three: Right configuration under the Standard viewports: list box. The preview screen will display the position and sizes of the three viewports.
Click the OK button. Your drawing will resemble Fig. 8.3. Notice that three viewports have been created and your drawing is seen in each of them though their position is somewhat arbitrary.
Place your cursor in any of the viewports and click. The border of the viewport becomes dark indicating that the said viewport has become active. You will find that only one viewport can be activated at a time. Go to the right viewport and activat it.
Command: Zoom or Z ↵ Zoom is initiated to scale the drawing as per your requirement.
Specify comer of window, enter a scale factor (nX or nXP), or [All/Center/Dynamic
/Extents/Previous
/Scale/Window] < real time>: E
Select ‘Extents’ and notice that your command is effective only in the active viewport.
Command: Pan ↵ Pan the object to place it at the center of the viewport.
Command: Z J Specify comer of window, enter a scale factor (nX or nXP), or [All/Center/Dynamic
/Extents/Previous/
Scale/Window] < real time>: 5 × ↵
Next, pick any point in the upper left vport to activate it and use the Zoom command again to impart scale.
  Type .5X (remember nX) to scale down the view. Repeat this with the lower left viewport and enter 2X here to double the scale. Your view will be as shown in Fig. 8.4.
Save the drawing.  

FIG. 8.3   Creating three viewports in model space

 

You can save the viewports assigning appropriate names to the respective viewports. The command prompts are as follows:

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Vports The Viewports dialog box reappears on the screen.
Type a name of the view such as ‘Pulley-1’ in the New Name: Text box and click OK. The name ‘Pulley-1’ is assigned to the viewport.

Now we shall see how to revoke the Named views. For that we shall first return to the original singleviewport configuration and then call back the three ‘Pulley-1’ configuration as described below.

 

FIG. 8.4   Three viewports with different scales

 

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Vports Set the screen to a single viewport by selecting the ‘Single’ configuration (Fig. 8.1).
  AutoCAD will display a single viewport, Zoom to Extents. Now recall the Viewports command again.
Command: Vports Pick the ‘Named Viewports’ tab and select the ‘Pulley-1’ configuration in the ‘Named Viewports’ list box and click OK.
  AutoCAD will display the Pulley-1 viewports, that is, the three viewports saved earlier.

Floating Viewport

Floating viewport is a bit more complex than tiled viewwports. You can understand from the previous section that tiled viewports are created to enhance drawing facilities in model space environment. On the other hand, floating viewports are meant for plotting in the paper space (layout tab). The location and size of floating viewports determines the extent of the plotting area and the view to be plotted. As the name suggests, floating viewport can overlap on one another. Some of the important features of floating viewports are highlighted below:

  • Since floating viewports are treated as objects, they can be moved, stretched, erased like any other drawing entity.
  • Unlike tiled viewports, they can be of different shapes.
  • Only one viewport is active at a time.
  • You can control layers within each viewport independently.
  • Floating viewport is very useful to display different views of one or more objects on a single plot.
  • For text, it is possible to ignore scale factor as the user works on the actual plotted page.

Creation of Floating Viewport

You can create floating viewports using the Mview command. Note that you have to be in paper space environment to create floating viewports. For paper space environment, press Layout 1 tab at the bottom of the drawing area. The detailed procedure of setting up paper space environment will be discussed later. The command sequences are as follows.

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Mview or mv ↵ Initiate the Mview command.
Specify comer of viewport or [On/
Off/ Fit/Hideplot/Lock/Object/
Polygonal/Restore/2/3/4] < Fit >:
Viewports can be created using different options. Some important options are mentioned here.
Other options: By the default option, a user can create viewport by specifying two comers of a viewport.
On/Off: If selected, this option will turn the display of the Model Space view On or Off within the chosen viewport in a Layout tab.
Fit: It creates a single viewport covering the whole screen in a Layout tab.
Object: This command allows you to create irregular-shaped viewports. You can draw (in Paper space) and select a closed Polyline, Ellipse, Circle, Spline, or Region at the prompt– ‘Select object to clip viewport:’ to define the boundary of your viewport as that of the object.
MODEL SPACE

From the above discussion on viewports, you can set up multiple views (tiled viewports) of a drawing in a single screen, under the model space environment. Working in multiple tiled viewports has some advantages and disadvantages. If several tiled viewports are displayed, editing in one viewport affects all other viewports. However, there is provision to set magnification, viewpoint, grid and snap settings individually for each viewport.

PAPER SPACE

Paper space is provided as an efficient plotting device that can create a finished drawing sheet using one or more scale and view of a component. First, draw the component in model space, then paste the drawing and other details on an imaginary sheet in paper space environment and get the plot. Without paper space, you would have to draw the model, its border line and title box in model space. Now, you need to draw only the model in model space. Then switch over to paper space to add border, title block, even dimensions and special instructions for the workshop that are not a part of the model.

Setting up Paper Space

Paper space is set up by picking Layout 1 tab, just below the display area. If it is selected for the first time, AutoCAD will open a dialog box (Fig. 8.5) with a heading Page Setup on the top. This dialog box asks you for the following information required for setting up the layout.

 

FIG. 8.5   Page Setup for paper space

 

Paper size   You can select the paper size (A0 , Al, and so on) through a control box.

Paper unit   You can choose the layout unit either in millimetres or inches.

Plot device   Provision to indicate the type of plot device to be used.

Drawing orientation   Choice of drawing orientation–Landscape or Portrait.

Plot area   Area of drawing to be plotted:

  1. Layout option: Plot area is based on paper size.
  2. Display: Plot area is based on drawing in model space.

Plot scale   Indicate the scale for plotting the drawing.

 

Once you have switched over to paper space environment, the standard X-Y icon (Fig. 8.2) which indicates model space environment, will change to a triangular icon as shown in Fig. 8.6. You may swap between Model space (Fig. 8.2) and paper space (Fig. 8.6) by simply typing MS or PS at the command prompt. Alternatively, you can toggle on the Status bar just below the command lines.

Scaling Views Relative to Paper Space

Before the plot, it is essential to introduce accurate scale setting for each viewport of the drawing. Scaling views relative to paper space establishes a consistent scale for each displayed view. Accurate scaling of the plotted drawing is very essential and for that the user must scale each view relative to paper space, not relative to the previous view or full scale model. You know that the scale factor represents a ratio between the size of the plotted drawing and the actual size of the model displayed in the viewports. This scale can be easily obtained by dividing paper space units by the model space units. For example, if the drawing scale is 1 : 10, you have to specify a scale factor of one paper space unit to 10 model space units (1 : 10).

You can use zoom to scale viewports relative to paper space units. The scale factor you enter is relative to the current paper space scale. If you enter a scale of 2 X P, the scale in the viewport increases to twice the size of paper space units. A scale of 0.5 X P sets the scale half the size of the paper space units, that is, the model is plotted at half its actual size.

Scaling Pattern Linetypes in Paper Space

Since paper space uses different scales for different viewports, the linetype scaling gets mixed up resulting in non-uniform linetype pattern. To avoid this, it is advisable to use a linetype scale based on paper space unit and not on model space unit. The system variable Psltscale becomes very handy to maintain the same linetype scaling for objects displayed at different zoom scale in different viewports. It also affects the line display in a 3-D view.

Example of Using Paper Space (Layout)

In all the previous sections, we have discussed in detail different features of model space and paper space and the advantages of using them. Since the concept is quite complicated, though very important, an example is necessary to highlight the use of paper space (Layout tab) to organise a drawing layout as per the requirement of the user so that plotting can be obtained easily.

The component was first developed in model space. Then, using the features of paper space, different views of the drawing are placed in different viewports. The scale for viewports can be incorporated as per need. Notice that dimensions, title block, border, and annotation in paper space do not become the part of model space environment.

Example Showing Use of Paper Space

We have given here an example showing the steps involved in creating paper space viewports. Students can follow this exercise step by step on their own sample drawing to master the concept of paper space.

AutoCAD Commands and Prompts Steps/Feedback/Options
Set the Vports layer current.

Pick Layout 1 tab that prompts AutoCAD to show the Page Setup Layout 1 dialog box on the screen. (This may sometimes take a few seconds.) If you use the Default option, click the OK button. AutoCAD will create a single Floating Viewport in Paper Space with your drawing as seen in Fig. 8.6.

 

FIG. 8.6   New default Layout in paper space

 

AutoCAD Commands and Prompts Steps/Feedback/Options

FIG. 8.7 Rename flyout

 

Let us now assign a name to the Layout. Right click the Layout1 tab and select Rename from the Rename flyout (Fig. 8.7). The Rename Layout dialog box (Fig. 8.8) will appear. Type ‘My Pulley’ in the text box and click OK. You will notice the new name on the Layout ltab. The dashed line indicates the working area on the page

 

FIG. 8.8 Rename Layout dialog box

 

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Save Save your drawing.
Command: Erase We shall now remove the default viewport by invoking the Erase command.
Select Objects: Select the viewport and press Enter. The viewport along with all drawings are erased. The viewports will be created afresh by the Mview command.

 

FIG. 8.9   Creating Viewports in paper space

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Mview or mv ↵ Initiates the Mview command.
Specify corner of viewports or [On/
Off/Fit/Hideplot/Lock/Object/
Polygonal/Restore/2/3/4/] < Fit >:
Here we shall create our own Viewports by picking corners as shown in Fig. 8.9. Pick the two ends of the viewports on the page area. You may choose any other option for selecting the viewport area also. After the selection of the two corners, you will find that your drawing has reappeared in the viewport (Fig. 8.10).

FIG. 8.10   Viewport with drawing

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: Circle or c ↵ Here we shall try to create non-rectangular type of viewport, for example, a circular one. The Circle command is initiated in the Paper space and a circle is drawn as shown in Fig. 8.10 along with the previously drawn rectangular viewport.
  After drawing the circle, initiate the MView command.
Command: Mview or mv ↵ Initiates the Mview command.
Speclfy corner of viewports or [On/
Off/Fit/Hideplot/Lock/Object/
Polygbnal/Restore/2/3/4/] < Fit >:
Select the object option by typing ‘O’ and press Enter.
Select object to clip Viewport: Select the circle. Your drawing will now look like as shown in Fig. 8.1 1. Note that AutoCAD will start with the full view of your drawing and clip it to fit to the circular area.

FIG. 8.11   Circular viewport created with the Object option of Mview

AutoCAD Commands and Prompts Steps/Feedback/Options
Command: ms Now to scale the viewports individually and to position the views properly, go back I to the model space by typing mspace or ms or pick paper on the status bar. If you want to display a blown up view of the groove portion in the circular viewport, activate the viewport by double clicking anywhere in it.
Command: Zoom or Z ↵ Specify comer of window, enter a scale factor (nX or nXP), or [All/Center/Dynamic
/Extents/Previous/
Scale/]
Set the scale for the viewport by using the Zoom command.
Window] < real time>: 2 X P ↵ Remember to enter the scale factor using the xp suffuc to indicate that you are scaling in Paper space. Type 2XP for scale.
Command: Pan or P ↵ If necessary, use the Pan command to get your view in the desired size and location. Your drawing will look like Fig. 8.12. In case you do not want to be bothered by scaling, you may use real time zoom to enlarge or reduce your view as per your reqirement

Now to add dimensions, text, title block, and so on, go back to paper space (you are in model space) and add the dimensions, text (view A, view B, and so on) marker arrow (by using the Pline command) and save the drawing. Your final drawing will look like Fig. 8.13.

 

FIG. 8.12   The scaled viewports in Paper space

 

FIG. 8.13   The final view of the drawing

EXERCISE
  1. What is model space? What are the limitations of model space?
  2. Why is paper space introduced in AutoCAD?
  3. Why are two types of viewports being provided in AutoCAD?
  4. How do you scale pattern linetypes in paper space?
  5. How many tiled viewports can you create on AutoCAD screen?
  6. What are the differences between a tiled viewport and floating viewport?
  7. Refer to Fig. 10.9 in which a rope pulley is displayed. Draw two views of the pulley along with rope cross-section in model space. Now use paper space (Layout 1) mode to generate an enlarged view (choose suitable scale) of the section of a rim. Use elliptical viewport to display the enlarged view.
  8. Refer to Fig. 10.12 in which a V-belt pulley is shown in solid model. Develop the solid model in model space. Use Layout 1 option to create the following three viewports:
    1. Left viewport contains two orthographic views of the object along with the necessary dimensions;
    2. Top right represents the isometric view of the solid model; and
    3. Bottom right shows the magnified view of the V-groove portion of the pulley.
  9. Develop the drawing of a pair of gears in model space shown in Fig. 14.7. Show the contact area within a pentagonal viewport in enlarged scale so that minute details of the drawing in that region is visible.
  10. Develop the drawing of a pair of rack and pinion shown in Fig. 14.15. Show the blown up view of the portion where contact takes place between the teeth.
  11. Generate the view shown in Fig. 8.13 for a V-belt pulley. Complete the title block and mention appropriate scale at the two viewports.
  12. Explain the difference between dimensioning in model space and dimensioning in paper space.
  13. If you drew it in model space, place your dimension in (model space, paper space).
  14. Fill in the blanks.
    1. The two ways to tell which space you are using are______and______.
    2. The keyboard approach to switching between Model Space and Paper Space is by using the commands______(or its hotkey “ms”) or______(or its hotkey “ps”).
    3. Access the viewports dialog box using the______command.
    4. It is easy to tell the difference between active and inactive viewports. Active viewports present_______while inactive viewports present a______.
    5. Paper space drawings should be plotted at a scale of______.
    6. Use the______command to create floating viewports.
    7. Any modifications to a viewport must be done in______space.
    8. Use the______command to reshape a viewport that was created by converting a closed polygon to a viewport.
    9. Reshape a standard rectangular viewport using the______command.
  15. State whether the following are true or false.
    1. It is possible to place a viewport configuration into a single active viewport.
    2. Tiled viewports will plot, so it is important to have them set up properly.
    3. Floating tiled viewports are objects that can be moved.
    4. Floating viewports must be rectangular.
    5. Unlike tiled viewports, more than one floating viewport can be active at a time.
    6. You can work in model space from a layout tab.
    7. You cannot work in model space on a layout tab.
    8. MVSetup can be used to set up model space.