MIT 4.202 Geometric Modeling Fall 2003
AutoCAD Tutorial
Drawing the Citrohan House

1. Before you start drawing, setup the units. [Format > Units] "units". The settings should be Length>Type:Decimal, Precision:0 Drag-and-drop scale>Millimeters
2. Try drawing a vertical line anywhere on the screen. Use the "line" command. Notice you cannot draw a truely vertical line. You need to turn on ortho mode to restrict the movement of the lines to only horizontal and vertical lines. Press F8 or click on the ORTHO button below the command line window.
3. Now we want to draw a horizontal line that is 15300mm from the vertical line we just made. First thing we have to do is to make sure we have object snap mode on. Click on the OSNAP button below the command window or press F3 to toggle the object snap mode. To change the settings, right-click on the OSNAP button.
4. Now use the "line" command and click on the bottom of the vertical line. Since we know what distance we want, we can type it in. At the command prompt, type @15300,0,0 and press return. This describes a line relative to the point we just clicked that is 15300 in the x-coordinate and 0 in the y and z coordinate.
5. Since the line is beyond our screen, we can use the "zoom" command to zoom out and see the entire drawing. The zoom command has a few options. Two of the more useful options are Extents, which zooms out to the extents of the drawing and window, which zooms in on a specific area.
6. Now we have a line that is 15300mm long. We now want the overall width of the building which is 6300mm. To do that we can use the "offset" command to offset the horizontal line. Type offset and it will ask you what the offset distance should be. Type 6300. Now click on the horizontal line and then click somewhere above it. You should now see another line. Press return to exit the command.
7. To complete the rectangle, we need to draw vertical lines. We can do this by using the line command and drawing a new line at the endpoints of the horizontal lines. But before we do that, we should probably erase the tiny vertical line we made before. Zoom in to see the tiny vertical line and use the erase command to erase it. Now zoom out and use the line command to draw a vertical line between the endpoints of the horizontal line.
8. To draw the other vertical line let's try using the copy command. Type copy and select the vertical line and press return. The copy command now asks for a base point. Click on the top endpoint of the vertical line. Now move across the drawing and click on the right endpoint of the top horizontal line. You should now have a rectangular box that is exactly 15300x6800.
9. Everytime you draw something, AutoCAD puts it on a particular layer. Right now we've been drawing on the default layer 0. You should never have anything on layer 0. To make new layers, use the layer command. It brings up a window which lets you create new layers. Let's make a couple of new layers as follows: 1) name:centerline, color:red, linetype:dashdot. 2) name:wall, color:white, linetype:continuous.
10. We want to move all the lines on layer 0 to layer centerline. You can do this by selecting each line individually (they should have grip boxes and turn dashed when selected) and then click on the layer pulldown menu to select the new layer. Another means of selecting multiple lines is to create a window by clicking and dragging. A window that is solid (dragging from left to right) will select only elements that are completely inside the window. A window that is dashed (dragging from right to left) will select any element that intersects the window border.
11. After the moving the rectangle to the centerline layer, the lines still look solid. What we need to do is to change the linetype scale for the drawing. Type "ltscale" and enter 500 as a value.
12. To create the walls, we can offset from the centerlines that we just made. The thin walls are 100mm and the thick walls are 300mm. After creating the lines, change their layer to be wall instead of centerline.
13. To fix the corners of the new wall lines, we can use either the fillet or trim command. Type fillet and click on the two outer lines. Make sure the radius is set to 0 otherwise you will get a little rounded corner. You can do the same with the inner wall lines as well.
14. To use the trim command, type trim, select the two lines that cross over and press return. These lines act as cutting lines. Now click on the part of the line that you do now want.
15. Now let's make the centerlines for the lower wall. It is 1100mm from the bottom horizontal line. It is also 1000mm from the left. Use the offset command to create these lines.
16. We can use the offset command to create the walls but instead we will use the copy command. Type copy, and select the two lines for the thicker wall. Press return to finish the selection. For the base point, pick the midpoint of the centerline. Now pick the midpoint of the centerline of the new wall. Use the fillet or trim command to finish off the corners of the wall. The end of the wall is 50mm from the centerline.
17. The beginning of the stairs starts 3550mm from the right wall. Use offset to generate the centerline and then select the line and drag the endpoint grip point below the wall. Now use trim to trim the wall length. Finally draw a new line to cap the end of the wall.
18. To save the drawing, type save [File>Save]. To save under a different name, type saveas [File>Save As...]. You should always your drawings with incrementally different names such as citrohan01.dwg, citrohan02.dwg, citrohan03.dwg, etc...
19. The interior room is 6200mm from the left end wall and 1200mm from the bottom thick wall. Use the offset command or the copy command to draw these centerlines.
20. To trim off the intersections between the walls, it might be easier to turn off the centerline layer and then trim away using the trim command.
21. The door opening on the bottom left is 900mm wide. Use offset to draw the opening.
22. To create the door jams, first create a new layer named door with the color yellow. Set the new layer as the current layer. The door jam is a 40x100 block with 20x30 block cut out of one corner. You can either use the offset command or draw the lines directly.
23. The jam is made up of individual lines. To group them as a unit, we use the pedit command. This turns the lines into a polyline. Type pedit and select one of the lines of the door jam. Since the line is not a polyline, it will ask you if you want to change the line into a polyline. Type yes. Now type join to select the join option because you want to join all the lines together. Type return to finish the selection and type return again to exit the pedit command.
24. Now when you select one line of the jam, the entire jam should be selected.
25. Move the jam into location against the end of the wall. Type move and select the jam and press return. For the base point, select the bottom right corner of the jam and then pick the bottom corner of the wall.
26. Mirror the jam to create the jam against the other wall. Type mirror and select the door jam and press return. In order to mirror an object you need to define the line in which the object will be mirrored. Create an vertical mirror line by clicking somewhere slightly above and then slightly below the jam. Type n so you don't delete the source object.
27. Move the new jam so that is it flush against the left wall. Type move and select the door jam and press return. Pick the left corner of the jam for the base point. For the next point, press ctrl-right-click and select Perpendicular. Now move the cursor over the left wall. The indicator icon should change to show perpendicular and then click.
28. Another method is to use the coordinate filter options. Type move and select the door jam and press return. Pick the left corner of the jam for the base point. Next type .x and press return. Now pick the wall. The command now needs to know the yz point. Click on the original base point you used.
29. To draw the door, use the rectangular command. Type rectangle and pick the bottom left and upper right corners of the opposite jam notches. Now rotate the wall into position. Type rotate, and pick the upper left corner of the door as the base and type 90 for the rotation angle.
30. To draw the door swing, create a circle and trim off the unnecessary sections. Type circle and select the bottom left corner of the door as the center and then click on the top left corner of the door. Now use the trim command and trim off the unnecessary sections. Type trim and select the door and the right door jam as the cutting edge. Now click on the lower part of the circle. You will have to zoom into the door jam to get rid of the excessive parts of the circle.

HL.2003.09.26