Delta triangle

Q: When revising drawings to include the delta triangle in the title block, does the drawing index sheet also contain the triangle in the title block?

A: The term “delta” refers to a triangle placed on the drawing for reference. The triangle is commonly placed next to a dimension, such as 2.65, 5, or other locations where it applies to a feature or item. This is used to refer the reader to a general note that relates to this item.

So if the delta triangle is used as a reference in your main title block, then I would say yes, add it to the index sheet if it makes the reference more clear.

In addition to drawing a reader’s attention to notes, the delta triangle is also quite often used with print revisions. For example, if a drawing was a revision 2, and then a new revision is generated. It might say something simple like, Rev. 3- 2.235 dimension changed to 2.240. Then a delta triangle with the number 3 in it would be next to the 2.240 dimension referring to the revision.

Bud Salsbury
ASQ Senior Member, CQT, CQI

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