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ASME Y14.41 - 2003 - Learn to deal with Basic Dimensions.

Another ASME Y14.41 - 2003 Tip

There are two types of dimensions-toleranced and basic. Dimensions that are toleranced may be toleranced on the field of the drawing, in a general note or a supplemental block of the drawing format. Basic dimensions are toleranced indirectly with geometric tolerances. The geometric tolerance applies to the feature, not the basic dimension. We have Rule #1 in the ASME Y14.5 standard which explains the meaning of a toleranced size dimension. For other than size, toleranced dimensions can have multiple meanings. For that reason, the ASME Y14.41-2003 standard on digital modeling recommends that direct tolerancing only be used to define the size of a feature [3.1.1, item(4)]. Geometric tolerancing is the preferred method. They do allow some direct tolerancing for other than size but in many cases recommend that the dimension origin symbol be used to clarify the meaning.

Here is a drawing made in accordance with the ASME Y14.41-2003 standard. Any dimensions not shown may be determined by making queries of the digital model.

Digital product data definition, reduced dimension drawings and paperless part definition will continue to grow in popularity. The sooner organizations embrace geometric tolerancing and use toleranced dimensions primarily for size, the sooner technology in this area will advance.


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