Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 1Autumn Quarter Topics For Today Drawing No. 16 is due now Lab report due on at the beginning of your lab period Descriptive Geometry Read BTG Chapter 11, Section 5

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 2Autumn Quarter Descriptive Geometry Graphics representation of the plane, solid and analytical geometry used to describe real (or imagined) objects It is the foundation, the underlying science of engineering technical drawings Traditional methods for solving spatial design problems: Direct view Revolution Fold-line

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 3Autumn Quarter Conventions and Definitions Lines and planes extend to infinity while we work with a small portion which we define. Lines and planes can be extended. Dihedral angle – The angle between two planes – smaller of the two. It can be found by finding the line of intersection and looking at the line of intersection as a point. Angle between a line and plane – This requires a view in which the plane is an edge and the line is true length.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 4Autumn Quarter Line Types Vertical, horizontal, or inclined Top Front If a line is parallel to one of the principal projection planes, it’s called a principal line Frontal (parallel to and true length in a frontal plane) Horizontal Profile TL

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 5Autumn Quarter Plane Types Horizontal Plane (True Size Projection In Top Or Bottom Views) AFAF BFBF CFCF ATAT BTBT CTCT TS Top Front

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 6Autumn Quarter Descriptive Geometry - Planes Vertical plane (appears as edge in top and bottom views) Profile (appears as edge in front view and is parallel to profile projection plane) Frontal (appears as edge in profile view and is parallel to frontal projection plane)

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 7Autumn Quarter Descriptive Geometry - Planes C TS Top ABC A B Frontal Profile TS D E F D F E E D F L L M M N N Inclined (Not TS!!)

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 8Autumn Quarter Descriptive Geometry - Planes X Y Z X Y Z Oblique (Not True Size Projection In Principal Views)

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 9Autumn Quarter Key to Descriptive Geometry Top Front Right Side Know the location of the origin (0,0,0)

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 10Autumn Quarter Descriptive Geometry with AutoCAD Download a blank3d template – 4 viewports, 3D construction, world coordinates, cursor tracking – world Layout mode – Transferring the model to paper – tab at the bottom of screen The layout and the model or construction mode are all part of one file.

Engineering H191 - Drafting / CAD Gateway Engineering Education Coalition Lect 9P. 11Autumn Quarter Today’s Assignment Download template from Web CT Dwg 17 – SGAC-3-1 Space Geometry in AutoCAD Pierce point of a line and a plane Due at end of class today Consult handout – steps for solving problems in AutoCAD are provided Dwg 18 – SGAC-3-2 Space Geometry in AutoCAD Intersection of Planes Due at beginning of next lecture Consult handout– steps for solving problems in AutoCAD are provided