GD&T

The following videos review GD&T concepts with a focus on how to inspect the requirements using the gages covered in other videos. Before watching the GD&T videos, it is strongly recommended to review or have a strong understanding of the following topics:

• Concepts
• Blueprint Reading
• Gages
• Hole Inspection
• Surface Plate Basics
• Surface Plate Accessories

 GD&T Inspection - 2 Hours [Youtube]
This video is a little different than the rest of the Gage series. In this video, I focus on how to inspect GD&T symbols. We will not spend too much time going into the details of the symbols. I feel that the engineering/requirements side of GD&T has a lot of good material coverage. But how to inspect is where this video focuses. Of course there are some basic explanations so we know what we are inspecting. For the main symbols we will discuss the different tools that can do the inspection, best practices, and do some demonstrations. This video will cover a wide range of gages from many of the other videos.
Position Error is not covered in full depth, rather a separate video is recorded (see below).

• Form Error: Straightness, Flatness, Roundness, Cylindricity
• Runout Error: Runout, Total Runout
• Position Error: Position (True Position), Concentricity*, Symmetry*
• Orientation Error: Parallelism, Perpendicularity, Angularity
• Profile Error: Profile of a Line, Profile of a Plane

*Even though Concentricity and Cylindricity are no longer in use, this video still covers possible inspections using hand tools and surface plate tools that are reasonable substitutions. These symbols have been used for decades and will continue to be on prints for years to come. It is important to understand them.

Position Error (True Position) - 1 Hour [Youtube]
In this video I discuss Position Error in depth by demonstrating with a real-time position calculator. This calculator can be found here at the Pragmatic Metrology for your use. Position Error itself requires no special gages, it is a re-interpretation of the shape of the tolerance zone from a rectangle to a circle. Whether or not position error is required, holes are verified by their size and centerpoint, so the gages are the same. In one example I will demonstrate with a height gage. However we will also discuss that, just like any inspection performed, the tool chosen should be based on the tolerance.

• Position Error (True Position) - Calculator
• Height Gage, Surface Plate, and Gage Pin.