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Put Your Holes at any Angle
(In accordance with Y14.5M-1994 standard)

PDF of this Tip

I keep hearing folks say that the primary datum used to control a hole must be at right angles to the axis of the hole. Not true! Pick your datums based usually on function. If some of the holes happen to be at an angle other than 90°, so be it. As long as the BASIC linear and angular dimensions used to locate the hole eventually get back to the datum, no problem. In this example, the 8.5 mm hole is not perpendicular to any of the datums referenced. The Ø0.4 mm positional tolerance is located by the 20 mm, 30 mm and 45° BASIC dimensions.

Back to Tips Tip added Apr 2000