Tolerance Analysis

#072 / Interview Mechanical Engineering Hard

Consider the below drawing of a front panel plate cutout. Assume the 3 holes line up perfectly along the vertical centerline.

Expand Hint

All the basic dimensions are controlled by the Composite Positional Tolerance. All bilateral dimensions are controlled by the block tolerances.

Hint 2

The tolerances will determine how much you subtract/add between dimensions. The question is basically asking the min and max distances/diameter.

The vertical spacings between holes A-B and B-C are controlled by the "2X 2.170" dimension, and are identical. Because "2.170" is a basic dimension, the Composite Positional Tolerance associated with the Hole A diameter callout will dictate the max range. The upper segment dictates the positional tolerance of Hole A relative to Datum B, while the lower segment determines the tolerance for the spacings between all three holes.
$$$2.170+(.005/2)=2.1725\:max\:distance$$$
The "3X ⌀1.485" callout for Hole A is a bilateral dimension that controls the diameters for all three holes. As a result, the drawing block tolerance controls this feature. Because the "⌀1.485" callout has three decimal places:
$$$1.485+.010=1.495\:max\:diameter$$$
The spacing between Hole A and Datum B is controlled by the "5.670" dimension. Because "5.670" is a basic dimension, the Composite Positional Tolerance associated with the Hole A diameter callout will dictate the max distance. The upper segment dictates the positional tolerance of Hole A relative to Datum B, while the lower segment determines the tolerance for the spacings between all three holes.

$$$5.670-(.012/2)=5.664\:min\:distance$$$

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