Drawing Setup with AutoCAD 2000 Part 1 : Introduction and Concepts

Transcription

1 Drawing Setup with AutoCAD 2000 Part 1 : Introduction and Concepts Dateline: 6/13/00 Introduction Drawing setup is generally the first - and perhaps the most important step - you'll make in creating CAD drawings. Proper drawing setup is a critical first step in drawing development, as many of AutoCAD's commands are dependent on settings made - or not made - during initial drawing setup. Improper drawing setup may result in undesired results when subsequently executing drawing, editing, or plotting commands. This multi-part article will address drawing setup in the AutoCAD 2000 environment. This first article will introduce the concepts necessary to understand drawing setup. In the coming weeks, follow-up articles will cover model space setup, using paper space layouts for plotting, and using templates for automated drawing setup. Concepts Drawing setup can be confusing if you're not familiar with some basic CAD drawing concepts. Before you even sit down at your CAD station to draw, you should have a basic understanding of drawing units, drawing scale, and drawing scale factors. Drawing units When you draw with CAD, every object you draw is measured in units. These units can be imperial or metric - feet or inches, meters or millimeters. You determine the value of these units during setup before you draw. Drawing unit settings control how AutoCAD interprets your coordinate and angle entries and how it displays coordinates and units in the drawing and in dialog boxes. AutoCAD supports the following system of units: AutoCAD Measurement Systems Measurement System Architectural Decimal Engineering Measurement Input / Display 1'-1-1/2" (input as 1'1-1/2") (inches or metric) 1'-1.5" (input as 1'1.5") Fractional 13 1/2 (input as 13-1/2) Scientific 1.35E+01 (inches or metric). The units you select will depend on your particular application. If you're an architect working with building floor plans, you may use architectural units where one drawing unit represents one inch. If you're an engineer working with civil site plans, you may use engineering units where one drawing unit represents one foot.

2 Drawing scale Drawing scales are used to describe the relationship between the plotted drawing objects and their corresponding real world measurement. For example, a drawing scale of 1/4"=1'-0" indicates that an object represented by 1/4" on paper actually measures 1'-0" in the real world. When we draw with CAD, objects should be drawn full-scale to their real world measurements. This differs from traditional manual drafting where objects were drawn to a particular scale on paper. Drawing scales allow us to work with objects in CAD in their real world measurements, and then scale them down for plotting and presentation. One of the real beauties of CAD (which is often taken for granted these days) is that once you've completed a drawing, you can plot it at different scales - something not possible with traditional manual drafting methods. Scale factors Scale factors are ratios or conversion factors between plotted objects and their corresponding CAD or real world measurements. Scale factors are derived directly from the drawing scale. For example, the scale factor for a drawing scale of 1/4"=1'-0" is 48. This scale factor is derived as follows: Scale factor derivation for drawing scale of 1/4"=1'-0" Convert both sides of the scale to the same units 1/4" = 12" Divide both sides of the scale by the value on the left 1" = 48" The scale factor is the resulting value on the right 48 Scale factors are used for many drawing tasks including drawing setup. During drawing setup, you will use the drawing scale factor to determine the working area - or limits - of the drawing. To calculate the working area of the drawing, we multiply the drawing sheet measurements by the scale factor. For example, if you have a sheet size of 22"x34", and you want to find the working area of a 1/4"-scale drawing, multiply each sheet dimension by 48. This yields a working area of 1056"x1632". Your work must not exceed these dimensions if you intend to have a final output of 22"x34" at 1/4"=1-0". Here's a handy reference table containing working area and scale factors for a variety of architectural and engineering drawing scales. We'll reference this chart in future articles regarding drawing setup.

3 Architectural Drawing Limits and Scale Factors by Drawing Scale and Sheet Size Scale/Sheet Size Scale Factor 8-1/2x11 11x17 17x22 18x24 3"=1'-0" 4 34x44 44x68 68x88 72x96 1-1/2"=1'-0" 8 68x88 88x x x192 1"=1'-0" x x x x288 3/4"=1'-0" x x x x384 1/2"=1'-0" x x x x576 1/4"=1'-0" x x x x1152 1/8"=1'-0" x x x x2304 1/16"=1'-0" x x x x4608 1/32"=1'-0" x x x x9216 Scale/Sheet Size Scale Factor 22x34 24x36 30x42 36x48 3"=1'-0" 4 88x136 96x x x /2"=1'-0" 8 176x x x x384 1"=1'-0" x x x x576 3/4"=1'-0" x x x x768 1/2"=1'-0" x x x x1152 1/4"=1'-0" x x x x2304 1/8"=1'-0" x x x x4608 1/16"=1'-0" x x x x9216 1/32"=1'-0" x x x x18432 Note : 1 Drawing Unit = 1 Inch Engineering Drawing Limits and Scale Factors by Drawing Scale and Sheet Size Scale/Sheet Size Scale Factor 8-1/2x11 11x17 17x22 18x24 1"=10'-0" 10 85x x x x240 1"=20'-0" x x x x420 1"=40'-0" x x x x840 1"=80'-0" x x x x1920 1"=100'-0" x x x x2400 1"=200'-0" x x x x4800 Scale/Sheet Size Scale Factor 22x34 24x36 30x42 36x48 1"=10'-0" x x x x480 1"=20'-0" x x x x960 1"=40'-0" x x x x1920 1"=80'-0" x x x x3840 1"=100'-0" x x x x4800

4 1"=200'-0" x x x x9600 Note : 1 Drawing Unit = 1 Foot

5 Drawing Setup with AutoCAD 2000 Part 2 : Model Space Setup Dateline: 6/21/00 Now that you have a fundamental understanding of CAD drawing setup concepts from Part 1, we can continue with this week's feature on model space drawing setup. Before you actually sit down at your workstation, fire up AutoCAD, and get started with drawing setup, you actually have a few decisions to make. You will need to decide what measurement system, drawing scale, and sheet size you will use. These decisions will likely be based on several factors - including your particular drawing application. For the purpose of this article, we'll use architectural units, a drawing scale of 1/4"=1'-0", and a plotted sheet size of 24"x36". This combination of units, scale, and sheet size is representative of many building projects, for example a residential floor plan or partial commercial floor plan. Model space drawing setup in the AutoCAD environment includes specifying the drawing units, drawing limits, and setting a few system variables. You may have noticed that I didn't mention drawing scale. Although you and I as a drafters and designers need to be aware of drawing scale, AutoCAD doesn't have a single drawing scale setting per se (hence the confusion with drawing setup). Instead a collection of settings enables the drawing to behave and plot as we'd expect at a particular drawing scale. Placing a title block is also part of drawing setup, which we'll cover separately in Part 3 of this series. AutoCAD has three methods for drawing setup. You can setup a drawing from scratch, using a drawing wizard (simple or advanced), or by using a drawing template. In this article we'll walk through drawing setup from scratch. Although drawing wizards can facilitate drawing setup they 'hide' many of the settings that you'll need to know to work with AutoCAD effectively. In Part 4 of this series, we'll take a look at how you can use drawing templates to save settings for various drawing scales and sheet sizes. Create New Drawing Let's launch AutoCAD and get started with drawing setup. In the Create New Drawing dialog box, click the Start from Scratch button, specify English as the default setting, and click OK to create the new drawing. (If AutoCAD doesn't display the Create New Drawing dialog on startup, choose File > New from the menu to display it). Set Units The first step is to set the units for our drawing. Although we've told AutoCAD to use English as the default setting, this doesn't control how distances are entered at the command line or displayed in the drawing window. To control these we need to specify the units - or measurement system. Units are controlled through the Drawing Units dialog box. 1. Choose Format > Units from the menu to display the Drawing Units dialog box.

6 2. In the Drawing Units dialog under Length, select Architectural from the list as the Type. 3. Leave the other settings with their default values for now. Click OK to close the Drawing Units dialog box. Set Limits The next step is to set the limits - or working area - of your drawing. The limits are a function of both drawing scale and sheet size. As you learned in Part 1, limits are calculated by multiplying the sheet size by the scale factor for the particular drawing scale. Alternatively, you can refer to this handy table of limits and scale factors. From this table, we see that the drawing limits for a 24"x36" sheet at 1/4"=1'-0" are 1152"x1728" - or more correctly 1728"x1152" when the sheet is landscape. With these known values we can proceed to set the drawing limits in AutoCAD. 1. Choose Format > Drawing Limits from the menu. 2. Press Enter to accept the default location of 0,0 for the lower left corner. 3. Type "1728,1152" and press Enter as the location for the upper right corner. 4. Choose View > Zoom All to zoom to the new drawing limits. Set Grid and Snap Grid and snap are drafting tools to assist in precision drafting. The grid is a visible array of equally spaced dots that appear on the screen within the drawing limits. The grid is useful as it provides a visual frame of reference for the drawing limits and can help you visually determine distance while working with your drawing. The grid is a visual display tool only - it is not plotted with the drawing geometry. Snap physically constrains the cursor movement to an invisible grid. Snap is useful if you want to pick points with the cursor while maintaining accuracy. Grid and snap spacing may or may not coincide. Grid and snap settings are controlled in the Drafting Setting Dialog box. 1. Choose Tools > Drafting Settings from the menu. 2. Turn Grid and Snap On by placing a check in the respective boxes. 3. Set the Snap spacing to 6" by typing 6 in the Snap X Spacing text box, then hit tab to automatically set the Snap Y spacing to the same. 4. Set the Grid spacing to 12" by typing 12 in the Grid X Spacing text box, then hit tab to automatically set the Grid Y Spacing to the same. 5. Click OK to close the Drafting Setting dialog box and apply the grid and snap settings. Tip : Grid and Snap can be toggled on/off with the F7 and F9 keys respectively. They can also be toggled on/off with the buttons on the AutoCAD status bar located at the bottom of the drawing window. Set Other System Variables

7 There are two scale-related system variables that you need to set to complete model space drawing setup. These system variables are LTSCALE and DIMSCALE. LTSCALE controls how non-continuous - or dashed - linetypes are displayed. DIMSCLALE controls how dimension arrows, text, and other components are displayed. LTSCALE should be set to 1/2 the drawing scale factor. DIMSCALE should be set equal to the drawing scale factor. 1. Type "LTSCALE" at the command prompt and press Enter. 2. Type "24" at the command prompt and press Enter to set the LTSCALE system variable. 3. Enter "DIMSCALE" at the command prompt and press Enter. 4. Type "48" at the command prompt and press Enter to set the DIMSCALE system variable. This completes model space drawing setup. Save your drawing (Arch_48) so we can refer back to it next week. We'll continue next week with Part 3 - using Paper Space Layouts where you'll learn how to prepare your drawing for plotting.

8 Drawing Setup with AutoCAD 2000 Part 3 : Paper Space Setup - Using Layouts Dateline: 7/11/00 This week we'll continue with drawing setup in the AutoCAD 2000 environment where we left of in Part 2 - Model Space Setup by focusing on paper space setup. Let's first make sure we have a fundamental understanding of the difference between model and paper space. AutoCAD has two primary drawing spaces - model space and paper space. Model space is where we create our full-scale 2D or 3D geometric model. Paper space is where we create our finished layout for plotting or presentation purposes. Each paper space layout represents (you got it) a piece of paper. Paper space layouts allow us to specify sheet size and drawing scale, place title blocks, specify plotters and pen tables, create model space views, and configure layers for plotting. Last week, we learned how to setup model space. This week, we'll finish drawing setup by learning how to setup a paper space layout. AutoCAD has two methods of configuring paper space layouts. We have the option of either using the create layout drawing wizard or configuring the layout manually. Although the drawing wizard can facilitate layout setup, walking through the layout setup manually will help develop a better understanding each step. This will give you the knowledge necessary to go back and modify the layout later if need be. Configuring a paper space layout involves the following : selecting a printer or plotter and pen table, specifying paper size and orientation, inserting a title block, and adding a model space viewport. Unlike previous releases of AutoCAD, AutoCAD 2000 stores your paper space layout settings with the drawing. Once you've configured and saved your layout, plotting is a simple matter of executing the plot command. Simple as that, no need to specify ANY additional parameters - they're all stored in the layout! Recall from Part 2 that we were working with architectural units, a drawing scale of 1/4"=1'-0", and a sheet size of 24"x36". We'll need this information as we proceed with paper space setup. Lets get started by opening the drawing we saved in Part 2 (Arch_48.dwg). If you don't have or didn't save last week's drawing, start a new drawing from scratch. Page Setup The AutoCAD status bar (located along the bottom of the drawing window) contains three model/layout tabs - Model, Layout1, and Layout2. Thus far, we've been working in the Model tab - aka model space. By default, AutoCAD 2000 drawings contain 2 additional layout tabs - aka paper space. The first step in setting up a layout is page setup. Page setup includes specifying a printer or plotter, paper size, paper orientation, plot area, and plot scale. 1. Click on the Layout1 tab. You should be presented with the Page Setup dialog box. If you are not, right click on the Layout1 tab, then select Page Setup from the popup menu.

9 2. In the Layout name text box, type a more meaningful name for your layout, like 24x Select the Plot Device tab. 4. Under Plotter configuration, choose the printer or plotter to use when plotting this layout (preferably - for the purposes of this exercise - one that supports 24x36 sheets). 5. Under Plot style table, choose the plot style table to use when plotting this layout - eg. acad.ctb. 6. Click on the Layout Settings tab. 7. Under paper size and units, select ARCH D - 24x36 or equivalent paper size. Select inches to represent the printable area. Note: The available paper sizes will depend on your specific printer or plotter. 8. Under Drawing orientation, select Landscape. 9. Under Plot area, select Layout. 10. Under Plot scale, select 1:1. Note: This is the plot scale not the drawing scale. Since the layout represents the physical area of the paper, we want to plot the layout at 1:1. Drawing scale will come into play when we place the viewport. 11. Select OK to close the Page Setup dialog and apply your layout settings. Note: You should now see a white border representing your blank sheet of paper. The broken line around the outside of the paper represents the printable area of the sheet. You will also see a rectangle in the lower left corner of the paper. This is the model space viewport that AutoCAD provides by default. Erase the viewport by clicking on an the edge to highlight it then pressing the delete key. Note: You can modify any of the layout settings in the future by re-issuing the Pagesetup command. Title Block Setup The next step in layout setup is to insert a title block. AutoCAD ships with one architectural title block. If you have access to your own custom title block, feel free to use it here instead. 1. From the AutoCAD menu, select Insert>Block. You should be presented with the Insert dialog box. 2. Click Browse then navigate to the AutoCAD 2000 Template folder or the location of your own custom title blocks. 3. Select Architectural Title Block or the name of your custom title block, then click Open. 4. Make sure the Insertion point, Scale, Rotation, and Explode options are all turned off (check boxes are empty) then click OK to insert the title block. The architectural title block or your custom title block should now appear on your layout. Viewport Setup

10 The final step of layout setup is to add a model space (floating) viewport with a scaled view of your model. A viewport is essentially a 'window' into model space. For most 2D drawings, a single viewport will suffice. 3D models may benefit from multiple viewports with different perspectives of the model. We'll add a single viewport configuration to the layout. 1. From the AutoCAD menu, select View>Viewports>New Viewports. You should be presented with the Viewport dialog box. 2. Click the New Viewports tab. 3. Under Standard viewports, select Single, then click OK. 4. Specify the location of the viewport on the layout by picking its corners. At this point you have created a viewport with an arbitrary scale factor. 5. To correctly scale the viewport we'll need the drawing scale factor from the drawing limits and scale factor table presented in Part 1 - Introduction and Concepts. Note that for a drawing scale of 1/4"=1'-0" the drawing scale factor is Double-click inside the viewport to make it active. The model space UCS icon should now appear inside the viewport and the viewport should be highlighted (bolder). 7. To display the drawing in the viewport at the desired scale, select View>Zoom>Scale from the AutoCAD menu, then enter 1/48XP at the command line. You've just scaled the view to the drawing scale relative to paper space. Note the use of XP and the drawing scale factor. If we'd been working at 1/16"=1'-0" we would have entered 1/192XP at the command line. 8. Double-click on the layout outside the viewport to return to paper space. 9. Adjust the position and size of the viewport as necessary. Use the move command to move the viewport around the layout. Click on the viewport and use its grips to stretch the viewport to make it smaller or larger. This completes paper space layout setup. Save your drawing (Arch_48) so we can refer back to it next week. Next week we'll conclude drawing setup by learning how to create and use templates for drawing setup.

11 Drawing Setup with AutoCAD 2000 Part 4 : Using Templates Dateline: 7/25/00 This week we'll conclude our lesson on drawing setup in the AutoCAD 2000 environment by learning to create and use drawing templates. CAD drafting can be repetitive and tedious as times. Thus we should be on the lookout for ways to streamline our routine and reuse our work. Templates present one such opportunity as they represent the most efficient method of creating new drawings. A template is simply a 'blank' file setup for a specific application. In much the same way that you use Word templates to create new faxes, memos, and transmittals, you can automate drawing setup by creating templates to create new drawings for the different sheet sizes and scales that you work with. AutoCAD comes with its own templates for ANSI, DIN, ISO, and JIS drawing formats - although I personally don't find these all that useful. Fortunately, we're not limited to these default templates - we can create our own. First we'll learn how to create a drawing template from an existing drawing, and then we'll learn how to use this new template to create a new drawing. Creating a Template Here we'll create a template from the drawing (Arch_48) we setup in Parts 2 and 3 - Model Space Setup and Paper Space Setup - of this series. 1. Start AutoCAD Choose File>Open from the AutoCAD menu. 3. In the Select File dialog box, locate Arch_48, then click Open. 4. Choose File>Save As... from the AutoCAD menu. 5. In the Save Drawing As dialog box, change the Save as Type to AutoCAD Drawing Template File (*.dwt) in the drop-down list. 6. Type Arch_D_48 in the file name text box, then click Save. 7. In the Template Description dialog, enter Architectural, D-Size, 1/4"=1'-0" in the description text box. 8. In the Template Description dialog, select English from the Measurement drop-down list and click OK. 9. Close AutoCAD You've just created your first drawing template.

12 Using a Template Now we'll use this new template to create a new drawing. 1. Start AutoCAD That's all there is to it! Tips 2. In the Startup dialog, click the Use Template button. 3. Select Arch_d_48.dwt from the Select a Template list box. Notice the drawing preview to the right and the description below. 4. Click OK. Although its probably not obvious, you've just created a new drawing with all of the model and paper space settings that we stepped through in parts 2 and 3 of this series - without the hassle! 5. To give your drawing a new file name, choose File>Save As... from the AutoCAD menu, locate an appropriate folder, type an appropriate file name, and click Save. If you find you're using a particular drawing setup frequently then it's probably a good candidate for a drawing template. Use the concepts and procedures from Parts 1-3 of this series to help you create templates for your frequently used setups. Once you've created a drawing template you can open it and modify it later just like any other drawing file.