Functional Datum Features - Episode 2

The GD&T Guy continues with episode 2 addressing "big question" about GD&T, which is about whether it is always necessary to have datum references to constrain a part in all 6 degrees of freedom, even if that means assigning datum references to features that do not play a role in locating a part in assembly. In this video, the GD&T Guy reviews the callouts he used on the circular part discussed in video one and evaluates whether some of the same tools could be used on a rectangular part. This leads into a detailed explanation of Simultaneous Requirements, which together with Functional Datum Features, he describes as a "one-two punch" has the ability to bring down the reigning idea that there always must be datum features adding up to 6 DOF. He ends with some example drawings that become possible if one accepts this idea. 08:07 Segment Five: Centerplane Secondary Datum - 6 and 5 DOF 15:32 Segment Six: Simultaneous Requirements - Axial Secondary 25:55 Segment Seven: Simultaneous Requirements - Centerplane Secondary 30:57 Conclusions from Episode 2 Free, downloadable pdfs of some of the drawings discussed in these videos can be found at: https://www.mountaintopdevice.com/gdt-guy-spring-2025