1. Geometric Dimensioning and Tolerancing

2. Lofty goals for the day Define these GD&T terms:
FCF, datum, tolerance zone, rule 1, MMC
Describe these GD&T characteristics:
flatness, parallelism, perpendicularity, circularity, position

3. MIL-HBK-727

4. MIL-HBK-727

5. Basic Dimension
Datum
Feature Control Frame
MIL-HBK-727

6. (See website listed online)

7. Datums

10. Rule 1-Indivdual Feature of Size
Where only a tolerance of size is specified, the limits of size of an individual feature prescribe the extent to which variations in geometric form, as well as size, are allowed. (ASTM Y ).
Meaning?

11. 5±1 6 4 9
10±1 11

12. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

13. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

14. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

15. Engineering Design Communication – Lockhart and Johnson

16. Fundamentals of Graphics Communication – Bertoline and Weibe

17. Position

18. Maximum and Least Material Condition (MMC & LMC)
MMC – The extreme size of the feature that makes the part weigh the most
LMC – The extreme size of the feature that makes the part weigh the least

19. Hole shown in blue at MMC (d=2.3)

20. The tolerance zone (.7) is illustrated in black

21. Four possible holes at MMC with their centers at the boundary of the position tolerance circle are drawn. In order to guarantee functionality, a pin must pass through the circle that overlaps them all possible holes at MMC, with their centers at the boundary of the position tolerance zone. The resulting shape is the Virtual Condition (VC) shown in orange.

22. SHAFT VC = MMC diameter + Position Tolerance Zone Diameter
HOLE VC = MMC diameter - Position Tolerance Zone Diameter

23. Summary
All dimensions include controls of geometry. Rule 1 states that a size control inherently includes controls of form.
Because of Rule 1, the need for GDT callouts is minimized. Use carefully.
GDT should be used to refine the relationship between feature and form.
GDT should open tolerances. MMC should reduce part cost.
Technical Graphics Communication, Bertoline, et al

25. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

26. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

27. Engineering Design Communication – Lockhart and Johnson
Fundamentals of Graphics Communication – Bertoline and Weibe

28. Fundamentals of Graphics Communication – Bertoline and Weibe

29. Fundamentals of Graphics Communication – Bertoline and Weibe

30. Regardless of Feature Size (RFS)
Maximum Material Condition (MMC)