In descriptive geometry for engineering drawing: when creating an auxiliary view to show the true shape/size of an inclined surface, what practical setup step should the drafter perform before projecting?

Introduction / Context:
An auxiliary view is used in technical and engineering drawing to reveal the true size and shape of a surface that is inclined to the principal planes (top, front, side). To construct this view accurately and efficiently in CAD, it helps to align your construction aids with the geometry of the inclined plane.

Given Data / Assumptions:

• The surface of interest is inclined relative to the standard projection planes.
• The drafter is using a CAD environment with a snap/grid or UCS that can be rotated.
• The goal is to lay out an auxiliary view perpendicular to the inclined surface so lengths appear true.

Concept / Approach:
The auxiliary view is created on a plane that is perpendicular to the inclined surface. In CAD, rotating the snap/grid (or aligning the UCS) to the same angle as the surface simplifies projecting perpendicular construction lines and placing dimensions that reflect true lengths. This mimics the manual technique of setting a miter or triangle to the correct angle.

Step-by-Step Solution:

Verification / Alternative check:
Measure a known sloped edge in the auxiliary view; it should equal its true length from design data. If it does not, check that the grid/UCS and projection lines are properly aligned at right angles to the inclined surface.

Why Other Options Are Wrong:

• Offset the right vertical line of the front view: Offsetting a single line does not establish a perpendicular auxiliary plane.
• Rotate the top line 45 degrees: The required angle is determined by the actual incline, not a default 45 degrees.
• Offset the top line 2 inches: Arbitrary distance does not control direction or orthogonality for true shape.

Common Pitfalls:
Forgetting to project perpendicular to the inclined surface or leaving the UCS at world orientation can lead to foreshortened results. Always ensure projection lines are perpendicular to the inclined face.

Final Answer:
rotate the snap grid to the same angle of the inclined plane