Topics For Today Quiz – CAEG – AutoCAD Drawing Number 18 is due Lab report due on Wednesday at the beginning of the lab period Lab Report – Follow the example, calc. % at each speed, graph in %, use two mph groupings (24 and 25 – avg 24.5) or three mph groupings (24 thru 26 -- avg 25) Descriptive Geometry Read BTG Chapter 11 Instructor: Give the quiz first. Today is the continuation of descriptive geometry that was introduced on Monday Autumn Quarter

Review from Monday 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. Instructor: Go through these again but ask the students to provide additional explanation about the first two bullets. Autumn Quarter

Review from Monday Downloaded 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. Instructor: Go over these steps with the students. Ask if anyone is having problems. Autumn Quarter

Review from Monday VIEW – Using UCS menu 3 UCS + plan (enter) (enter) – gives true size of plane Z UCS + plan (enter) (enter) – gives end view of line which could provide edge view of a plane or a dihedral angle Instructor: The instructions given here refer to the steps in the previous two problems. The UCS is the Universal Coordinate System. Asking the system for these views provides the true size of a plane and the edge view of the plane. Autumn Quarter

Construction Hint When you have created a line and then look down the line so the line appears as a point, it disappears in AutoCAD. When you know this is going to happen, place a point (+) at each end of the line. Save often but don’t overwrite the blank3D file. Instructor: It is easier for the students to solve the problems if they always put a point marker (normally a + sign) at each end of any lines that they draw. Autumn Quarter

Key to Descriptive Geometry Top Know the location of the origin (0,0,0) Front Right Side Autumn Quarter

Angle between a line and plane Required – a view where the line is true length and the plane is an edge In pencil construction, three auxiliary views are required 1) edge view of plane 2) true size of plane 3) edge view of plane and true length of line Using the UCS menu and the PLAN command shortens the process Instructor: Read through the instructions for today’s problems in the file labeled SGAC-4 Angles.doc with your students. Autumn Quarter

Today’s Assignment Dwg 19 – SGAC-4-1 Angle between a line and a plane in space Due at end of class today Read Handout – steps for solving problems in AutoCAD are provided Dwg 20 – SGAC-4-2 Dihedral Angles Due at beginning of next lecture Read Handout – steps for solving problems in AutoCAD are provide Autumn Quarter