GD&T Tolerances & Fits in Engineering Drawings 2

Question 1

A shaft is specified as ⌀50 -0.010/-0.030. What is the maximum shaft diameter?

Accepted Answer

49.990 mm

Answer

The upper deviation is -0.010, so maximum shaft diameter = 50.000 - 0.010 = 49.990 mm.

Question 2

Which ANSI/ISO fit system uses the hole as the fixed reference with H designation?

Accepted Answer

Hole-basis system

Answer

In the hole-basis system, the hole deviation is fixed (H) and the shaft deviation varies to achieve the desired fit.

Question 3

A clearance fit is achieved when the minimum clearance between mating parts is:

Accepted Answer

Positive

Answer

A clearance fit always has a positive minimum clearance, meaning the shaft is always smaller than the hole.

Question 4

What does the term 'allowance' refer to in tolerance and fit terminology?

Accepted Answer

The minimum clearance or maximum interference between mating parts

Answer

Allowance is the intentional difference between mating parts — minimum clearance for clearance fits or maximum interference for interference fits.

Question 5

A hole tolerance is specified as ⌀25 H7. If H7 corresponds to +0.021/0.000, what is the minimum hole diameter?

Accepted Answer

25.000 mm

Answer

For H-designation holes, the lower deviation is always zero, so minimum hole diameter equals the nominal size of 25.000 mm.

(GD&T) Geometric Dimensioning and Tolerancing Certification Practice Test