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Inspection Guides
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Most engineers and designers recognize that they must take into consideration manufacturing processes when designing a part. However, many engineers fail to consider the subsequent inspection of the manufactured part. Inspection must work with the drawing and the part to make sure that the part is exactly what the designer intended it to be. That's why Gary Whitmire has produced the following Inspection Guides for Drafting Zone's community.

Over the past 60 years locating of features of size, such as holes, has been accomplished many different ways. We have gone from plus-and-minus dimensioning with square tolerance zones to diameter tolerance zones with formal datums.

To inspect even a simple part to ensure that all design requirements are met is a fairly extensive multi-step process. This example helps you understand the ramifications of your design requirements on both manufacturing and inspection.

This Guide tells you how to measure the roundness of a part. Measuring this factor is quite different from measuring a feature such as length or the location of a hole.

The process of inspecting for perpendicularity, parallelism and angularity is very similar, but it is complex and not easily understood.

This Guide provides a better understanding of the GD&T flatness and straightness callout (per ASME Y14.5M-1994) and shows how this callout can be measured using open inspection setups and hard gages.

This Guide provides an overview of ASME Y14.43, Dimensioning and Tolerancing Principles for Gages and Fixtures. Also included is a step-by-step form to help you establish the correct tolerances for the functional gage that will be used to inspect the part.

A good reason to use GDT dimensioning on compound angles is that it makes inspection easy and fast. In this inspection guide Gary shows you how this is accomplished.

Zero Tolerancing does not mean that a part must be perfect. In this guide, Gary Whitmire shows, via an example, how zero tolerancing can be effectively used.

In GD&T, the Projected Tolerance Zone is an area above a threaded hole or clearance hole. If the projected tolerance zone is not specified for certain design conditions, the part(s) may not assemble. This guide not only describes how inspection will measure the hole, but also the potential problems that may be encountered.

This Guide addresses the inspection process of a spotface, which is a machined surface area that provides a level and perpendicular seating area for a screw or bolt head, nut, washer, or similar item.

This Inspection Guide covers the many rules associated with measuring holes. Measurements must be done in accordance with ASME inspection and engineering rules in order to guarantee interchangeability and part function. When it comes to dealing with interchangeable parts, all inspection and engineering personnel must understand this very important subject.

This Inspection Guide covers the measuring and inspection of a pattern of holes in relation to a datum of size.

This Inspection Guide deals with Concentricity, which is the most misunderstood Geometric Dimensioning & Tolerancing (GDT) symbol used on engineering drawings. Very rarely is concentricity a practical thing and if used on a drawing, it creates a headache for the Inspection Department. The true meaning of concentricity requires inspection to find the absolute mathematical center point of each cross-sectional slice through a given shape (or as many cross-sections as can be taken). Each of these points must fall within the specified tolerance.
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