Recognizing defaults is a bit tricky because they do not appearВ on a drawing. This toolbox approach requires users to choose from several tolerancing tools to select the one that is best suited for their applicationДo you know which defaults from the ASME Y14.5 standardВ apply to your drawings? To correctly read a drawing, you must be able to recognizeВ the defaults from Y14.5 and understandВ where they apply. It also can be confusing because it contains tolerancing tools that are not useful in a particular company. Having a standard that is like a giant toolbox is useful because it provides tolerancing tools that are needed for most applications in many companies. The Y14.5 standard includes tolerancing tools for many applications. The Y14.5 standard is similar to the giant toolbox. It would also be bad because there would be tools that you were not familiar with and you might end up using them in the wrong places. The giant toolbox is good because you could use the tools that you are familiar with to do many jobs. This toolbox has so many tools that knowing how or when to use all the tools would be difficult. The tools could handle almost any kind of plumbing, electrical, or mechanical repair job that came along. Imagine you were in a contest and won a giant toolbox filled with hundreds of different tools. T he Y14.5 standard is like a giant toolbox with tolerancing tools for all sorts of applications. The list below contains a few examples of disallowing or discouraging a concept, symbol, or modifier. A few tolerancing tools that are only used in rare applications may be disallowed or discouraged to prevent their widespread use. A few tolerance tools are overly restrictive for most applications or are not a good tool for your companies' applications. Tolerancing tools can be disallowed for a variety of reasons. The addendum focuses the discussions by disallowing or discouraging certain tolerancing tools leaving the tolerancing tools needed for defining your products. There are often discussions over which symbol is better for an application. There are subtle differences between some of the GD&T symbols.

There are also tolerancing tools that are not used often.

There are many tolerancing tools in the Y14.5 toolbox that are not needed for some types of parts. Discouraging or disallowing the use of a symbol or concept is important because it reduces the number of tolerancing tools available for use on drawings.

Asme y14.5 symbols