Engineering Sketching (not in your book)

ENGR Graphics Fundamentals Orthographic Drawings – 3 views Isometric Drawings -- easy 3D view Line types and weights – show centers, and hidden lines Dimensioning -- showing lengths

Describing an Angle Bracket

Orthographic Projection Orthographic drawings represent three dimensional objects in three separate views arranged in a standard manner.

Orthographic Views You can adequately describe most objects with three orthographic views. Front Top Right

Converting to Orthographic

Construction of Views Must align orthographic views Width appears in Top and Front Height appears in Front and Side Depth appears in Side and Top Height and width project directly Depth must be projected via a 45° angle

Step 1 - Lightly Block Three Views Use very light lines for drawing in the construction lines Instructor: Construction lines are to be drawn lightly, gray vs. black, so that they will not reproduce on a Xerox machine and therefore do not have to be erased.

Step 2 - Lightly Block Major Features

Step 3 - Add Features, Use Miter Line Instructor: Note that the miter line is an alternative to “counting and measuring” when going from right side to top view. It helps show the connection between the two views. The miter line is not required.

Steps in Creating the Three-View Sketch Step 4 - Add Final Lines Instructor: The construction lines on the students’ drawings will be light gray and if the final lines are added and then made darker, the three views should appear.

Steps in Creating the Three-View Sketch Completed Sketch Instructor: Again, the construction lines are left off visual for clarity. Students can leave construction lines if done lightly.

Think-Pair-Share In the next 1 minute as an Individual if you could ask a question . . . specifically what don’t you understand about today’s topic what would it be. [at least 3 items should be listed] Now take 2 minutes to merge your list with the person sitting next to you AND add 1 new item to the list In the next 5 minutes share the results with the other half of your team, delete questions that you can answer for each other, AND prioritize the remaining questions your list

Team Exercise Complete three orthographic views of the object shown on the next slide. Include visible, hidden, and center lines where appropriate. Use the grid paper in the back of your book or your engineering sketch pad. You will be given 7 minutes.

Object for exercise

ISOMETRIC DRAWINGS

Isometric Drawings Isometric is the easiest way to create a fairly realistic 3D sketch of an object lengths are preserved on each plane

Making an Isometric Sketch - Defining The Axis (use iso-grid paper) Isometric Axis Instructor: This series of slides is intended to first define the isometric case as a specific case of axonometric, where axis are both at 30 degrees to the horizontal.

Making an Isometric Sketch - Axis Convention Depth Width Height Isometric Axis Convention Instructor: Conventions for height, width and depth are show here. We will define: front face and one that has height and width right side as on with height and depth top as view of width and depth look down at object

How would you sketch this object? Object for Practice How would you sketch this object? Instructor: This is just a sample object to show the recommended way of developing an isometric sketch of an object.

Blocking in the Object – Begin with Front Face Height Width Front Face Instructor: Strongly recommend that they start by lightly sketching in a box that would contain the whole object. Then later the parts not needed will be extracted. This series does Front, Right Side and Then Top. Start with Isometric Axis

Blocking in the Object – Add Side Face Height Depth Side Face Instructor:

Blocking in the Object – Add Top Face

Adding Detail – Cut Outs – Part 1 Instructor: After box is in place, use construction lines (light lines) to define volumes to be removed. In this example, this is done in three pieces.

Adding Detail – Cut Outs – Part 2

Adding Detail – Cut Outs – Part 3

Darken Final Lines Instructor: We need to encourage the students to leave their construction lines (lightly done), so that we can check their process as well as final product. Both are important.

Draw an Isometric View of this object Step 1: Front Face Step 2: Right Face Step 3: Top Face Step 4: Remove material Step 5: Darken lines

Dimensioning It is important that all persons reading a drawing interpret it exactly the same way. Parts are dimensioned based on two criteria: Basic size and locations of the features Details of construction for manufacturing Standards from ANSI (American National Standards Institute) Instructor: It is not only critical that everybody using a drawing interpret it the same way, it is important to do the dimensioning in the simplest way. There are lots of ways to dimension an object following the standards and yet have a drawing that is difficult to read. In Engineering, the ANSI standards are available for lots of different areas and they are not just about engineering graphics.

Dimensioning Shows: Size Location & Orientation Instructor: The figures on the left only show size. This figure is incomplete without adding the location and orientation dimensions.

Scaling vs. Dimensioning Drawings can be a different scales, but dimensions are ALWAYS at full scale. Instructor: Here is an important concept. Scale deals with how you draw something – the dimensioning is always done at full scale. Remind your students that while the computer is comfortable with any scale, you want the final drawing printed at some recognizable scale. These recognizable scales would be the ones that were discussed earlier in the term. For example, if you are printing a set of house plans you probably want them in ¼” = 1 foot or 1/8” = 1 foot.