1. Instructor: James Thornburgh
Unit 1 GD&T
Instructor:
James Thornburgh
Agenda:
Objectives
What is GDT?
Why it’s Important
Measuring
Break

2. Objectives Identify and draw GD&T Symbols Correctly use GD&T symbols
Describe Maximum and Minimum material conditions
Describe and correctly apply Datums
Identify various inspection tools
Demonstrate the use of measuring devices.

3. What is GD&T?
GD&T is a way of dimensioning that takes into account function and fit with related parts.

4. Why GD&T is important Are Parts Made exactly to the drawings?
GD&T allow drawing to be more accurately dimensioned, with looser tolerances.

5. Why GD&T is important

6. Measuring & Inspection Devices
Help you to determine if a part is to spec.
Open
You measure the piece by it’s self
Functional
You put the piece in a fixture to determine if it’s good
Go, No-Go Gauges

7. Calipers
Vernier
Dial
Digital

8. Reading Vernier Caliper

9. Reading Vernier Caliper

10. Micrometers
Vernier
Digital

11. Reading Vernier Micrometer

12. Surface Plate

13. Height Gauge

14. Dial Indicator

15. CMM

16. Material Conditions MMC LMC Maximum Material Condition
When a Feature Weighs the Most
Small Hole, Large Object
LMC
Least Material Condition
When a Feature Weighs the Least
Large Hole, Small Object

17. Material Conditions
RFS
Material size doesn't matter for Tolerance

18. GD&T Symbols

19. Control Types
Form Controls
Orientation Controls
Location Controls

20. Form Controls
Straightness
Flatness
Circularity
Cylindricity

21. Form Controls

22. Flatness
Microscopic View of surface

23. Flatness

24. Orientation Controls
Parallelism
Perpendicularity
Angularity
Profile

25. Orientation Controls

26. Angularity

27. Profile

28. Location Controls
Position
Concentricity
Runout

29. Position What is the shape of a normal Tolerance Zone? 2.00±.02
. 02
2.00±.02
.75±.02

30. Position
What is the Max it can be out of position?
. 02
. 03

31. Position The Position Tolerance sets a round Tolerance Zone
Use Basic Dimensions that have Zero Tolerance
Symbolized by drawing a Rectangle around Dim

32. Position
2.00
.75
Ø2.00
Ø.02

33. Runout

35. Defining Datums

36. Defining Datums

37. Feature Control Frame
Houses GD&T Symbols

38. Datums for Plane

39. Datums for Axis & Centerline

40. What do They all Mean?

41. What do They all Mean? Datum B Feature 11.9 12 38.6 0.4 0.5 38.5 0.6
Datum B
Feature
11.9 12
38.6
0.4
0.5
38.5
0.6
38.4
0.7
38.3
0.8
38.2
0.9
38.1
1.0
38.0
1.1

42. Lab Assignments & Homework
Measuring Handout
Workbook
Homework
Read Ch 16
Do Review Questions 1-10