Enginneering graphics?

Question

http://img204.imageshack.us/img204/5161/graphicszh6.jpg

Hey i have to do these graphics for my engineering course but i missed my second lesson so im not really sure how to do it, i get the example question the only thing im confused about is why do they extend lines vertically on the top view. Could someone do or explain how to do some of the others there cos i have no idea and maybe a brief explanation of what each image represents i might be missing something. thanks heaps

Answer 1

http://people.virginia.edu/~rlk4v/scanedDrawing.jpg

Because it is a 3rd angle project, the views are (counter clockwise from the top) Top, Front, Right. So the object is displayed as if you were looking at it directly from the top, front or right side accordingly (1st angle projection is different, but I digress).

Dashed lines are "hidden lines." Aka. lines which exsist in the object, however from that certain point of view you would not be seeing.

In general, you want to see where certain aspects of the geometry line up. Sketching lines from one view to another (as I did in my drawing) often helps.

Answer 2

In the top view of the example, the lines that extend vertically are showing the part that juts out on the other side.
To do the other ones, take one view (side for example) and in your mind, extend all its horizontal lines to the front view. If any of the imaginary lines aren't already drawn on the front view, draw a dotted line there. Do that with all the views.

Hope that helps.