The GD&T Blog

Several months ago I wrote about the requirements for becoming certified as a “GD&T Professional.”   (View that blog entry here.)    This time, I would like to present some advanced questions.

There are two levels of certification for GD&T Professionals: Technologist and Senior. You do not need to be certified at the Technologist level in order to take the Senior level exam.  But you would need to be sure that you are very familiar with all the tricky nuances of GD&T!  (Plus, you must submit a letter of verification that you have been regularly involved with GD&T for at least five years.)

So the following are a few questions that might be representative of the more difficult stuff.  Answers are at the end, along with the appropriate paragraph number from the 1994 edition of Y14.5… 

Sample question #1:

The derived median plane of a feature can best be described as:

  a. a theoretically perfect plane through the center of a part’s actual mating envelope

b. a plane that coincides with the centerplane of the true geometric counterpart

c. an imperfect plane passing through center points of all line segments bounded by the feature

d. an imperfect plane representing the average height of a surface plate used to simulate a datum surface

Sample question #2:

Simulating equalized datums may be accomplished by using:

  a. pins

b. V-type knife edges

c. V-type planes

d. all of the above

Sample question #3:

For the drawing given above, the minimum permissible distance between the outside of the part and the edge of a hole is:

  a. 16.6

b. 16.65

c. 16.8

d. 16.95

Sample question #4:

The dimension line of an angle should be:

  a. an arc

b. normal to the extension line

c. parallel to the extension line

d. angled to the extension line

Sample question #5:

For the following print, a part of Ø9.17 would be _______ .

a. a good part

b. a bad part

c. good, only if statistical data is monitored

d. good only if a stack is calculated

Sample question #6:

In the following drawing, the .008, .005, and .002 tolerances control ________ respectively.

a. location & size; orientation; form

b. location & perpendicularity; location; form

c. location; orientation & size; form

d. location & orientation; perpendicularity; size & form

Here are the answers:  1=c (paragraph 1.3.15), 2=d (4.6.6), 3=b (4.5.3 and 5.4.1), 4=a (1.7.1.3), 5=c (2.16), 6=d (6.5.9.1)

More information about the official ASME test can be found at their website:

http://www.asme.org/Codes/CertifAccred/Personnel/Y145_Geometric_Dimensioning.cfm

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