Auxiliary projections: a secondary auxiliary view is constructed by projecting from which previously established view?
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AFront view
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BTop view
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CPrimary auxiliary view
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DNone of the above
Answer
Correct Answer: Primary auxiliary view
Explanation
Introduction / Context:Auxiliary views are used to display true shapes of inclined or oblique features. Sometimes a single auxiliary view still shows another edge foreshortened; a secondary auxiliary view resolves that by projecting again from the first auxiliary.
Given Data / Assumptions:
- A primary auxiliary view already exists and shows one feature in true size.
- Another direction remains foreshortened in the primary view.
- The goal is to obtain true size in this remaining direction.
Concept / Approach:A secondary auxiliary is projected from the primary auxiliary, not from the original front/top views. The new projection plane is perpendicular to the direction that is still inclined, producing true lengths and shapes for that orientation.
Step-by-Step Solution:
Identify the edge/axis that remains foreshortened in the primary auxiliary.Establish a secondary auxiliary plane perpendicular to that edge/axis.Project points from the primary auxiliary onto the secondary plane.Connect points to reveal true size/shape in the secondary auxiliary.Dimension on the secondary auxiliary for accurate lengths/angles.Verification / Alternative check:Check that known edges now measure their true design values. If not, confirm perpendicularity of the secondary plane to the still-inclined direction.
Why Other Options Are Wrong:
- Front/Top view: Projecting from the original views does not resolve the remaining inclination.
- None of the above: The correct source is the primary auxiliary.
Common Pitfalls:Accidentally projecting from the wrong view or forgetting to orient the secondary plane correctly leads to persistent foreshortening.
Final Answer:Primary auxiliary view