Engineering drawing abbreviations and symbols
Engineering drawing abbreviations and symbols are used to communicate and detail the characteristics of an engineering drawing. This list includes abbreviations common to the vocabulary of people who work with engineering drawings in the manufacture and inspection of parts and assemblies.
Technical standards exist to provide glossaries of abbreviations, acronyms, and symbols that may be found on engineering drawings. Many corporations have such standards, which define some terms and symbols specific to them; on the national and international level, ASME standard Y14.38 and ISO 128 are two of the standards. The ISO standard is also approved without modifications as European Standard EN ISO 123, which in turn is valid in many national standards.
Australia utilises the Technical Drawing standards AS1100.101, AS1100-201 and AS1100-301.
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"6-⌀6.8 EQS PCD 50" means "drill 6 holes of 6.8mm diameter equally spaced on the Pitch Circle Diameter ⌀50."I
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oc on centerOD outside diameter
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On a technical drawing a dimension or note that is given only for reference and therefore is not intended to be used as a part acceptance criterion. Parenthesis value denote the same thing and were standardized by ASME.When a dimension is defined in one view but also mentioned again in another view, it will be given as reference in the second case. This rule prevents the mistake of defining it in two different ways accidentally; the "main" mention is the only one that counts as a feature definition and thus as a part acceptance criterion. See also basic dimensions, which are similar in some respects.