Size Matters




Users may need to select parts from a range of similar parts only differentiated by size.


How to depict parts so that small dimensional differences between similar parts can be identified.


  • Some assemblies require the use of fasteners or elements that are very similar in appearance and only differentiated in dimension. Parts that make up the Lego™ system are a common example of this.
  • Some parts will not possess clear discernable details that can be indicated on an illustration to differentiate them from similar parts.
  • Due to foreshortening perspective views are not useful for communicating precise dimensions of parts.


A one-to-one scale elevation of the item on the illustration must be portrayed so the user can compare the actual elements against the drawing.

This requires communication that the elevation is presented at a scale of one to one.

The illustration requires discernable details so that the user can relate the elevation to the depiction of the element in the perspective view.

If one to one depiction is not possible due to the part sizes exceeding the page size its length must be indicated with a numeric dimension.


Drawn from practice and inspection of existing artifacts.

Related Patterns:


Discernable Detail

Elevations may lack details required for part identification.


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Author - WorldMade PAIs created and evaluated as part of the thesis.

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