Engineering design

W7-2

Professor: Oscar Alonso Rosete Beas

Agenda

• Unit 2 introduction
  • Orthographic Projection
  • Multiview drawings
  • Third-angle vs First-angle projection

Portfolio draft (10)

Portfolio draft (11)

Portfolio draft (12)

Projections

Multiview projection shows one or more necessary views. Either of two systems is used to arrange the views in a multiview drawing: third-angle or first-angle.

The standard published in ANSI/ASME Y14.3 is common in the United States, where third- angle projection is used.

Europe, Asia, and many other places use the first-angle projection system (ISO).

Projections classification

Third-angle projection

In third angle projection, the 3D object to be projected is placed in the third quadrant and is positioned behind the vertical plane and below the horizontal plane. Unlike in first angle projection where the plane of projection is supposedly opaque, the planes are transparent in third angle projection. This projection method is mainly used in the United States and Japan stipulates the use of third angle projection schema for industrial designs for product fabrication.

Third-angle projection

If the object to be drawn is placed below the horizontal plane and behind the vertical plane, as in the glass box, the object is said to be in the third angle. In third-angle projection, the views are produced as if the observer is outside, looking in.

Unfolding the glass box

Third-angle projection

First-angle projection

The orthographic view typically consists of the top view, front view, and the side view. First angle projection is one of the methods used for orthographic projection drawings and is approved internationally except the United States. In this projection method, the object is placed in the first quadrant and is positioned in front of the vertical plane and above the horizontal plane.

First-angle projection

In first-angle projection the observer looks through the object to the planes of projection. The right-side view is still obtained by looking toward the right side of the object, the front by looking toward the front, and the top by looking down toward the top; but the views are projected from the object onto a plane behind the object in each case.

Summary video

Third-angle and first-angle symbols

Third angle

First angle

Summary

Third-angle Examples

Frame of 1 cm

Include the title block in the bottom right corner

Title block (ISO):

• Title: Draft #13, created by: Your name, Approved by: Professor´s Name

• Include the date in which it was drawn.

Units expressed in mm.

Try to horizontally and vertically center your draft on the remaining blank space.

Draw the component´s three principal views in first-angle projection and repeat the procedure with third-angle projection.

Include at least 1 rear view

Include the annotations

Multiview-drawing

Portfolio draft (13)