AutoCAD isometric setup — appropriate use of the Offset tool In an isometric drawing, the Offset command should primarily be used to place which type of edges so that parallelism and spacing are maintained correctly?

Introduction / Context:
In isometric drafting, edges along the three principal isometric directions are drawn at specific orientations: two at 30 degrees from the horizontal (left and right isoplane) and one true vertical. The AutoCAD Offset tool creates parallel copies at a given distance. Knowing when Offset yields precise results helps maintain accuracy and speed in production drafting.

Given Data / Assumptions:

• Isometric axes: two axes inclined at 30 degrees and one vertical axis.
• Offset creates lines parallel to a selected object at a specified distance.
• Isocircles are made with the Ellipse command (Isocircle option), not Offset.

Concept / Approach:
Offset works best when creating multiple, equally spaced parallel elements. In an isometric view, vertical edges are genuinely vertical in the 2D screen plane; offsetting a vertical line yields another perfectly vertical, parallel line separated by a precise distance. While Offset can also create parallels for lines at 30 degrees, many workflows recommend precision placement using polar tracking at 30 degrees for those axes and reserving Offset primarily for true verticals to avoid compounded picking errors and to align with shop conventions.

Step-by-Step Solution:

Verification / Alternative check:
Check a typical isometric box: offsetting a vertical edge by a known distance reproduces a clean, parallel vertical edge, matching dimensions reliably. For isocircles, Offset cannot generate correct ellipses corresponding to circles in 3D; Ellipse (Isocircle) is required.

Why Other Options Are Wrong:

• Circles / isocircles: created via Ellipse > Isocircle, not via Offset.
• Horizontal lines: true horizontals do not exist in isometric; those edges are at 30 degrees and better handled with polar tracking.
• None of the above: Offset has valid use on verticals.

Common Pitfalls:

• Attempting to Offset an isocircle to “thicken” it; this will not maintain the correct ellipse geometry.
• Using Offset indiscriminately for 30-degree edges without polar tracking can introduce tiny misalignments.

Final Answer:
vertical lines