In this Question Line video, Jason answers the following question regarding controlling profile for a pattern of surfaces:
We have a profile of a surface callout for 5 surfaces. Two of these surfaces are also specified as datums within the profile (chicken/egg thing). There are questions about interpretation. Please see attached.
Jason walks through the submitted drawing below in answer to this question:
The submitted drawing shows a profile callout to five surfaces, controlling the profile of these surfaces to .012” with respect to A and B. Datum Features A and B are two of the surfaces within the profile itself. In this video, Jason walks through the drawing, explaining the problem this would cause for inspection. He then discusses options for updating this drawing, including creating an advanced datum that allows all 5 surfaces to be identified together as a pattern of surfaces. This advanced datum lends a hand to inspecting with a functional gage when the datum is referenced at MMB (Maximum Material Boundary).
Got GD&T questions? Submit them at the link below:
https://www.gdandtbasics.com/share-your-gdt-questions/
If your question is selected, we will notify you when our video answer is posted to our YouTube channel.
* If you are a current student, reach out to us directly and we will get you into contact with your instructor. Active students’ questions receive a direct response within 24-48 hours.
Overwhelmed by the Complexity of GD&T?
Learn GD&T at your own pace and apply it with confidence in the real world.
Get Your GD&T Training