1. Instructor: James Thornburgh
Unit 1 GD&T
Instructor:
James Thornburgh
Agenda:
Inspection & Gauging
5 Steps to GD&T
GD&T in AutoCAD
STP

2. Inspection & Gauging Functional Gauging Open Gauging Feature of Size
Using Fixtures to check a part
Go/ No-Go Gauges
Open Gauging
Using Measurements to inspect
Tells you what is Wrong
Feature of Size
Things that can be directly measured

3. Functional Gauging

4.  ± .002
10.000
15.500

5. C
 ± .002
 .001 M A B C
10.000
Note: Datum A forms the bottom surface of the hole, and so the tolerance zone is a perfect, right cylinder – resting on Datum A and located from Datum B and Datum C. B
15.500 A

6. C
 ± .002
 .001 M A B C
10.000
It tells us the size and shape of the tolerance zone for the hole center B
15.500 A

7. C
 ± .002
 .001 M A B C
10.000
In this case, when the hole is at its’ smallest permissible size, the feature location is in its’ most critical state. B
15.500 A

8. C
 ± .002
 .001 M A B C
In this case, when the hole is at its’ smallest permissible size and perfectly located, the feature is in its’ most critical state, and just fits about the red gage pin. B A

9. Total Effective Tolerance
10.000
 ± .002
 .001 M A B C B
15.500
Produced Hole Size
Geometric Tolerance
Feature Size ‘Bonus’
Total Effective Tolerance
11.197
out of size tolerance
11.198
.001
11.199
.002
11.200
.003
11.201
.004
11.202
.005
11.203 M

10. 5 Steps Isolate & define function Prioritize the Functions
Identify Datum Reference Frame
Select proper Control
Calculate Tolerance Values

12. GD&T in AutoCAD
Menu
Dimension
Tolerance
Keyboard
tol

13. GD&T Dialog Box
Diameter
Material Condition

14. GD&T Dialog Box

15. STP Statistical Process Control
Process for checking the quality of parts
Keeps track of trends in production

19. ANSI Limits and Fits Running & Sliding Locational Force
Allow clearance space for lubrication RC
Locational
Between mating parts
LC, LT, LN
Force
Tight fits FN
Appendixes 7-11

20. Lab Assignments
Lab
Prob