Ch.7 Auxiliary Views

Auxiliary view projection theory and why we need it (7.1) Two referencing methods (7.1.1 and 7.1.2) Auxiliary view classification (7.2) Procedures to create primary and secondary views (7.2) Other auxiliary views: Full view and Partial view (7.2.5 &

7.2.6) See figures 7.11 and 7.12 Dealing with curves (7.2.7) Auxiliary view applications (7.3

Objective: Learn how to create primary and secondary auxiliary views using the Fold-Line method and the Reference Plane method

Auxiliary view projection theory Why we need it?: A true size and shape plane is shown

only when the line of sight used to create the view is perpendicular to the projection plane. Oblique line, inclined plane and oblique plane never have their true shape shown in the six principal planes. Hence, we need to create a view whose line of sight is perpendicular to these line and planes if we need to show their true size.

Auxiliary view projection theory (cont)

Let’s see in 3D how the aux view projection theory works

Notice that in this cut, the auxiliary plane is perpendicular to the frontal plane.

Two referencing methods: Fold-line and Reference plane

Fold-line method

Note the fold lines are parallel to the edge lines of the planes. This means that the fold line is perpendicular to the projection lines (lines of sight).

Two referencing methods: Fold-line and Reference plane (cont)

Reference plane method

What’s the difference between the two methods? Not much. Watch carefully. The folding line just moves to the edge or inside the object instead of away from the object, to a location that makes it more convenient to drawn an auxiliary view. That’s about it.

Auxiliary view classifications: Primary, secondary, tertiary, etc.

Procedures to create primary and secondary views To find the true size of an inclined line or

plane, you need a primary auxiliary view. An incline line shows in the true size in one of the principal planes.

Procedures to create primary and secondary views (cont)

To find the true size of an oblique line or plane, you need a secondary auxiliary view.

Full view, half view, and partial view It is normal not to project hidden features or other

features that are not part of the inclined surface. A partial auxiliary view saves time and produces a drawing that is much more readable. Half auxiliary views are used for symmetrical objects; again this saves time.

Dealing with curves

Just like pictorial views, a method similar to the offset coordinate method is used.

These lines are parallel.

Auxiliary view applications

Reverse constructions Used when you cannot draw a principal view without a help of reverse construction.

It is very difficult to draw this right-side view without having an auxiliary view. (This uses the offset coordinate method to transfer the circle to the right-side view.

Auxiliary view applications (cont)

Dihedral angles: A dihedral angle is the angle between two planes. To draw and measure the angle between two planes, create a point view of the line of intersection between the two planes (meaning that the fold line is perpendicular to the line of intersection between the two planes.

Sample 1 (inclined plane)

Sample 1 (inclined plane) (cont)

Sample 2: Inclined place with a curve

Sample 2: Inclined place with a curve (cont)