AutoCAD R12 Tutorial 2


	FBE AutoCAD Page

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

Introduction

In this tutorial you will learn how to edit graphics(!) and to set model-space limits. You will draw a simple plan based on Frank Lloyd Wright's 1956 Guggenheim Museum, New York.

Figure 1 Form study of Wright’s Guggenheim Museum

Starting AutoCAD

Start AutoCAD, by selecting it from the workspace menu. Once AutoCAD has drawn the graphics window, double-click at the top of the AutoCAD window, this will make AutoCAD 'take over' the whole of your computer screen.

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 and inches.

Setting the Limits and Units

We use metric, therefore must reset the LIMITS; type:

    limits [return]                This sets the drawing
    0,0 [return]                   “size” to be
    50000,50000 [return]           50x50 metres.

Next we need to get rid of the 4 decimal points! Type:

    units [return]      should bring the text window to the front!
    2 [return]          this selects decimal units.
    0 [return]          no decimal points!
      [return]          you don't need to type "1"
      [return]          no decimal points.
      [return]          set 0 degrees = east.
      [return]          use anticlockwise = positive angles.

If you press [return] AutoCAD uses the “default” choice - which is specified in brackets at the end of the list of options.

These sets the "model space" dimensions. To reset the drawing view to the whole of the [empty] drawing, type:

    z [space] a [space]       “z” is short for ZOOM,
                              “a” is short for ALL.

Remember that [space] = [return]

Move the cursor around now and note that the coordinates are now bigger numbers!

Let the drawing begin!!

In this tutorial you will draw a simple plan based on Frank Lloyd Wright's Solomon R. Guggenheim Museum, New York 1956. The drawing you will draw comes from Clark R. and Michael Pause, "Precedents in Architecture", VNR 1985, page 135 (see figure 1). I am assuming, for this exercise, that the 5x5 cm plan = 50x50m.

Firstly draw a rectangle from 0,0 to 50000,50000, you should remember how to do that from last week!

Then draw a circle, centred at 30000,24000 with a 6000 radius. Type:

    c [return]                “c” is short for CIRCLE.
    30000,24000 [return]      the circle centre.
    6000 [return]             the circle radius.

Next you will draw another circle, with the same centre, but with a 9500 radius. Press [return] to “recall” the last command.

Select the CENTER snap mode: use the right mouse button. Then pick the first circle with the left mouse button; this places the centre of the new circle at the centre of the existing circle. Then type:

    9500 [return]             the circle radius.

Draw the Building "Wing"

Next you will draw a rectangle from the centre of the circles to 39500,33500.

Once you have done that draw another rectangle to the right of the last, start at 39500,24000 and make the rectangle 1500x9500.

Hint: use a relative coordinate @1500,9500.

Now you will draw an arc on the end of the last rectangle (see figure 2). Select:

    /Draw . Arc . Start,Cen,End/

Then select the Endpoint Snap Mode and select the bottom-right of the last rectangle. For the centre point of the Arc, select the Midpoint Snap Mode 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.

Figure 2 Shows the location of the ARC.

Save the Drawing

Once you've done the arc, save the drawing, type:

    save [return]
    tut2 [return]

Copy & Rotate the Building Wing

Now we want to copy & rotate the two rectangles and the arc (3 times), unfortunately, AutoCAD doesnot have a copy-rotate command! It has a rotate command but that does not have a copy option :

To achieve what we want, we will save the graphics as a named "block" and then insert that block 4 times! Type:

    block [return]
    quarter [return]          this becomes the name of the block.

Put the "insertion base point" at the bottom-left of the first rectangle; select the Endpoint Snap Mode and pick the rectangle corner. AutoCAD then prompts for you to select the objects to be included in the block, pick the two rectangles and the arc, by clicking on them with the left mouse button, you will notice the objects turn purple when picked! When you've picked the three objects press [return] - this shows that you have finished selecting objects.

If that succeeded then the three objects would have disappeared!

Inserting Blocks

Once your heart has stopped palpitating, type:

    insert [return]           give it back... :-)
    [return]                  the default shoud be "quarter".

For the insertion point select the Center Snap Mode and select one of the circles, this places the shape back in the centre of the circles. The press:

    [return]                  use the default X scale (1).
    [return]                  use the default Y scale (1).
    [return]                  use the default rotation (0 degrees).

Now press [return] to restart the command. Then choose the same insertion point and scales but type 90 [return] for the rotation; this places the objects rotated 90 degrees!

Now, insert the objects rotated at 180 and 270 degrees (see figure 3).

Figure 3 Drawing with all 4 building “wings” in place.

Converting Blocks Back to Ordinary Graphic Objects

Now that we have inserted these blocks we need to "explode" them back into ordinary lines, so we can delete parts. Type:

    explode [return]

Select the four blocks by clicking on them (with the left mouse button); when all four copies have turned purple, press [return]. The blocks are now converted back into their constituent parts!

Let's first edit the "top-right" corner. Your need to erase one edge of both rectangles. Before you can erase the edges you must explode the rectangles into Lines! Select:

    /Modify . Explode/

select both the rectangles and then press [return]. If AutoCAD doesn't display any error messages then the explode command worked!

Erasing Graphics

Now to erase the edges, type:

    e [return]                "e" is short for "erase",
                              which is in the Modify menu.

Click on the right edge of the inner rectangle, and press [return]. Now type:

    r [return]                "r" is short for "redraw".

Figure 4 Lines in "bottom-right" wing to be erased.

Now we erase the other line there! Select:

    /Modify . Erase/

Click on the line and press [return]

To see if you understand, explode the two rectangles in the "bottom-right" corner and the erase all the "inner" lines (see figure 4).

Finally, you need to edit the "bottom-left" corner. You will stretch the "wing" of the building and then remove the inner lines. Select:

   /Modify . Stretch/

Figure 5 Stretch selection rectangle.

Draw a selection rectangle around the arc and THROUGH the first rectangle (see figure 5). Then press [return] to terminate the selection process. Then click with the left mouse button near the selected objects, and type:

    @-10000,0 [return]

If that worked the building wing should stretch 10 metres. Now you need to explode the both the rectangles in the wing and erase the vertical lines, except the line from the centre of the circles.

One Last Circle....

The last object to add is a circle inside the arc on the "bottom-left" corner. Type:

    c [return]                This is short for "circle"

Select the Center Snap Mode and click on the arc; then type:

    3600 [return]             the circle radius.

Save the Drawing!

Type:

    qsave [return]            Save the drawing!

More Explosions....

The drawing is basically complete, you simply need to change some of the line-types and your done! Select:

    /Modify . Explode/

To select all the rectangles at the centre of the original circles, type:

    c [return]                chooses a "crossing" selection set.

Then click below and to the left of the centre and then click above and to the right - crossing the centre. AutoCAD should say "7 found, 6 were not a block, dimension or polyline", this is OK, just press [return].

The are 8 lines going to the centre (4 are "covered" by the others). You need to erase 4 of them! Type:

    e [return]

then click on each of the four lines and finally press [return].

Type:

    r [return]                Redraw!

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, it is necessary to set the line-type-scale, which controls how the line-types are displayed....

Select (from the screen menu on the right.):

    |Settings . next . LTSCALE|

Then type:

    2000 [return]

This is necessary to make our dashed lines show up dashed on-screen. Type:

    chprop [return]           Change Properties

and click on the four lines, the arc at the "top", and the arc on the "right", then press [return], and type:

    lt [return]               elects to change line-type.
    hidden [return]           linetype = "hidden" = a dashed line!

then press [return] to terminate the command.

The objects should be redrawn using dashed lines (see figure 6).

Figure 6 Finished form study of Wright’s Guggenheim Museum

The End!

Type:

    end [return]              save drawing and exit AutoCAD.

To log off, move the mouse to the (blue) screen background and click the RIGHT mouse button, then click "Exit..." and finally click "Exit" to confirm the action!


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