2D AutoCAD - Tutorial 2


	FBE AutoCAD Page

Stephen Peter, S.Peter@unsw.edu.au

This tutorial has been prepared for students at the Faculty of the Built Environment studying AutoCAD in Communications Seminar 3. It has been placed on the Web to facilitate access by those students and because I believe others may find the material of use!

While the tutorial is aimed at people using the Windows version of R13, I have (where possible) given the commands to be typed in addition to the toolbar icon.

Note that throughout this document I am using the character "" to symbolise the [Enter] and [spacebar] keys and the Right mouse button.

Stephen Peter, 31 July 95.


Introduction
	In this tutorial you will learn how to edit graphics(!) and about to set model space limits. You will draw a simple plan based on Frank Lloyd Wright's 1956 Guggenheim Museum, New York.
This drawing comes from Clark R. and M.Pause, "Precedents in Architecture", VNR 1985, page 135.	Figure 1 Form study of Wright's Guggenheim Museum
Starting AutoCAD
The top-right coorrdinates could be as high as 24,13!	Start AutoCAD, and then move the cursor to the bottom left of the screen, you will note the coordinates (on the status line) go down to near 0,0. Now move the cursor to the top right of the screen, the coordinates go to about 13,9. These "defaults" are keyed to people using imperial units: feet/inches.
Setting the Limits and Units
	We use metric, therefore must reset the limits; type: `LIMITS` `0,0` `50000,50000` This sets the drawing "size" to be 50x50 metres.
If the coordinates didn't change to no decimal places after completing the command, move the mouse!	Next we need to get rid of the 4 decimal points! Select Data - Units, AutoCAD will display the "Units Control" dialog box. Make sure Decimal is selected in the Units section and Decimal Degrees in the Angles section, then in Units Precision, click on the down arrow beside "0.0000" and select "0", and finally select "OK".
This should bring the AutoCAD text window to the front. If you press AutoCAD uses the "default" choice - which is specified in brackets at the end of the list of options.	As an *alternative* to the above, type: `UNITS` `2` this selects decimal units. `0` no decimal places. you don't need to type "1". no decimal points. set 0 degrees = east. use anticlockwise = positive angles.
`Z` is the alias (shortcut) for `ZOOM`. Remember that `[space]` = .	This sets the "model space" dimensions. To reset the drawing view to the whole of the (empty) drawing, select zoom-all from the standard toolbar (or type: `Z [space] A [space]` ). Move the cursor around now and note that the coordinates are now bigger numbers!
Let the Drawing Begin!!
This shows us the "drawing area".	Firstly draw a rectangle from 0,0 to 50000,50000, you should remember how to do that from last week!
`"C"` is the alias for CIRCLE.	Then draw a circle, centred at 30000,24000 with a 6000 radius. Select (or type: `C` ), then type:
	`30000,24000` the circle centre. `6000` the circle radius.
To get AutoCAD to display the Object Snap Modes toolbar, select "Toolbars" from the "Tools" menu and then select "Object Snap".	Next you will draw another circle, with the same centre, but with a 9500 radius. Press: to "recall" the last command. Select the centre snap mode (or type: `CEN` ), then pick the first circle (*NOT* the centre of the circle), then type:
	`9500` the circle radius
Draw the Building "Wing"
	Next draw a rectangle from the centre of the circles to 39500,33500.
Hint: use a relative coordinate @1500,9500.	Once you have done that draw another rectangle to the right of the last, start at 39500,24000 and make the rectangle 1500x9500.
	Figure 2 Shows the location of the ARC.
The ARC icon show here is in the ARC-flyout. Hold the mouse button down over the arc icon on the draw toolbar and select the icon.	Now you will draw an arc on the end of the last rectangle (see figure 2). Select (this selects the "start-centre-end" arc), then select the Endpoint snap mode (or type: `END` ) and select the bottom-right of the last rectangle. For the centre point of the Arc, select the Midpoint Snap Mode (or type: `MID` ) and select the middle of the right edge of the last rectangle. For the end of the Arc, select the Endpoint Snap Mode and select the top-right of the rectangle.
Save the Drawing
	Save the drawing: select (or type: `QSAVE` ), if you are prompted for a drawing name, select the appropriate Drive and Directory and type a drawing name (for example: `TUT2` ) and select "OK".
Copy & Rotate the Building Wing
	Now we want to copy and rotate the two rectangles and the arc (3 times), AutoCAD provides the array command to achieve this. The array command is used to copy one or more objects in either a rectangular or circular pattern and when a circular pattern is used the objects can be rotated....
Polar Array is on the copy flyout (under copy ) on the Modify Toolbar. The `"W"` tells AutoCAD that you want to draw a selection "window".	Select polar array, AutoCAD will prompt for the objects to be selected: type: `W` , click below and to the left of the bottom-left corner of the left rectangle and then move the mouse until the selection rectangle encloses the two rectangles and the arc - then click the mouse button (3 objects should be selected). Then press to end the selection process.
After selecting the Centre snap mode, pick the circle NOT the centre!	AutoCAD will then prompt for the centre of the array. Use the Centre snap mode to select the centre of the circles. Then type:
	`4` the number of items. accept 360 degrees. accept "rotate as copied".
	Figure 3 Drawing with all 4 building "wings" in place.
Exploding Objects!
For convenience, in the following section, I'll talk of the "top-right wing" and the "bottom- right wing". By the "top-right wing" I mean the first rectangles and arc that you drew, and the "bottom-right wing" is the rectangles and arc in the bottom-right corner!!	Now we need to erase some of the lines we've drawn. When the rectangle command is used the rectangle that is drawn is a "polyline" which means that all the lines that make up the object are joined together, the lines must be "exploded" before any parts of the rectangle can be erased.
	Select: from the modify toolbar (or type `EXPLODE` ) select both the rectangles in the "top-right corner" and then press . If AutoCAD doesn't display any error messages then the explode command worked!
	Figure 4 Lines to be erased.
Erasing Objects
`"E"` is the alias for "erase". `"R"` is the alias for "redraw"	To erase the edges, select from the modify toolbar (or type: `E` ). Click on the right edge of the inner rectangle, and press . Select (or type: `R` ). Now we erase the other line there! Select erase again, click on the line in the same place and press .
	To test your understanding: explode the two rectangles in the "bottom-right wing" and the erase all the "inner" lines (see figure 4).
Stretching Your Wings
`"C"` tells AutoCAD that you will create a "crossing" window. The normal selection window selects only those objects wholly within the section window. A crossing selection window selects objects that are wholly or partly within the section window.	Now you need to stretch the "bottom-left wing" and then remove the inner lines. Select (or type: `STRETCH` ). Type `C` and then draw a selection window around the arc and through the small rectangle (see figure 5), press to terminate the selection process, click with left mouse button near the selected objects, and type: `@-10000,0` (this is the "stretch distance"). If that worked the building wing should stretch 10 metres.
	Figure 5 Stretch selection rectangle.
	Now explode both the rectangles in the "bottom-left wing" and erase the vertical lines, except the line from the centre of the circles.
One Last Circle...
`"C"` is the alias for "circle".	The last object to add is a circle inside the arc of the "bottom-left wing". Select (or type: `C` ). Select the Center snap mode (or type: `CEN` ) and click on the arc; then type `3600` (the circle's radius).
Save the Drawing!
It's always worth saving your work regularly!	Select (or type: `QSAVE` ).
More Explosions and Deletions...
The drawing is basically complete, all that needs to be done is to change some of the line-types!	Select: from the modify toolbar (or type `EXPLODE` ), select all the rectangles at the centre of the original circles (use a crossing selection window), and then press . If AutoCAD displays a message saying that some objects could not be exploded - ignore the message - it's simply saying that some of the rectangles have already been exploded.
	The are 8 lines going to the centre (4 are "covered" by the others). You need to erase 4 of them, select erase from the modify toolbar (or type: `E` ), then click on each of the four lines and finally press .
	Select redraw from the standard toolbar (or type: `R` ), you should now be able to see the lines that were under the lines you erased!
Changing Line Types
	Before changing some of the lines to dashed lines, we need to load the linetype(!). Select Data - Linetype..., then select "Load...". AutoCAD will display a list of linetypes, select "HIDDEN" (you will need to scroll through the list!), then select "OK", then select "OK" again to dismiss the "Select Linetype" dialog box.
	Select change properties from the "Objects Properties" toolbar, pick the four lines going to the centre of the original circles and the arcs in the "top- left" and "top-right" wings (see figure 6), then press . AutoCAD will display the "Change Properties" dialog box, select "Linetype...", pick "HIDDEN" from the list and select "OK". Then replace the "1" in the Linetype Scale text field with `2000` and finally select "OK"..
	The objects should be redrawn using dashed lines (see figure 6).
	Figure 6 Finished form study of Wright's Guggenheim Museum
The End
	That's all for tutorial two! Save your drawing and then exit AutoCAD (or type: `end` to save and exit). Remember to log off before leaving.

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2D-R13 Tutorial 3


Last Update : 8 April 2000 Major Revision : 29 July 1997 SEARCH . FBE SITEMAP		Disclaimer . Webmasters Page Contact : Stephen Peter Email : s.peter@unsw.edu.au