Introduction to Geometric Dimensioning and Tolerancing
Advantages
Allows designer to describe the design intent.
Advantages
GD&T is Absolutely Succinct. There is no extra information, and everything has a precise meaning.
Trying to convey the same information with notes would be extremely difficult.
Advantages
It is a graphical language, can be used internationally.
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Advantages
Since the tolerances can refer to specific geometric qualities, it allows for wider tolerances that are easier to attain.
Here are two examples...
Hole Position
Consider the following:
Think about the tolerance zone
Think about the tolerance zone
How much can the center be away from target?
hmmmm....
GD&T will let us create a tolerance zone that is round. That will allow us to use a more generous tolerance.
Table Example
Table Example
Using GD&T To Control Flatness Separately from Height
Tolerance Zones
Can be shaped like (perfect)
Cylinders
Tubes
Spheres
Flat disks
Ribbons
Flat Plates
Contoured “Skins”
Need to be located exactly
Datums
Datums describe how the tolerance zone is to be located in an exact way.
The top surface of the block must be parallel to the blue datum surface to within the geometric tolerance.
The size tolerance is shown in green.