Name:
open book and notes ; calculator, but no computer
50 minutes
EML 2023
Summer 2012
1. A bearing is to be press fit into the hub of a wheel. The nominal size of the outer surface of the
bearing and the inner surface of the hub is  1.36. What tolerances would you specify for the
bearing and hub diameters for a FN1 force fit?
bearing:
1.36.0013
.0009 inches
hub:
1.36.0006
.0000 inches
2. An axle is to spin freely within a bushing. The nominal preferred size is 50 mm. What tolerances
would you specify for the axle and the bushing if a hole basis free running fit was desired?
The fit is classified as H9/d9. The size limits for the axle and the bushing are obtained as
axle:
49.858 to 49.920 mm
bushing:
50.000 to 50.0062 mm
Questions 3 through 10 refer to the part drawing that is provided.
3. Sketch the datums on the drawing to the right.
B
C
A 4
What is the Least Material Condition for hole #1?
LMC is 12.4 mm.
5. What is the perpendicularity tolerance for the through hole of hole #2 if the hole is manufactured with
a size of 5.52 mm?
The perpendicularity tolerance will be the same as the position tolerance. At a size of 5.51 mm, the
position tolerance will be (0.25+0.02) = 0.27 mm.
6. What is the smallest allowable distance between points 1 and 2?
The ‘perfect’ distance between the points is 38 mm. Due to the flatness criteria of datum feature C,
point 1 can be a maximum of 0.2 mm closer to point 2. Due to the profile criteria between points A
and B, point 2 can be 0.25 mm closer to point 1. Thus the smallest allowable distance between points
1 and 2 will be 38 – 0.2 – 0.25 = 37.55 mm.
7. What is the largest allowable distance between points 1 and 3?
The ‘perfect’ distance between the points is 32 mm. Due to the profile criteria between points A and
B, point 1 can be located 0.25 mm further away (downward) from point 3 and point 3 can be located
0.25 mm away (upward) from point 1. Thus the largest allowable distance between points 1 and 3
will be 32.5 mm.
8. What is the largest allowable distance between the centers of holes 3 and 4?
The ‘perfect’ distance between the hole center points is 25 mm. The position tolerance for both holes
is given as 0.2 mm regardless of feature size. Thus the center point of each hole can move 0.1 mm
away from the other and the largest allowable distance is 25.2 mm.
9. What is the smallest allowable cross sectional area of slot 1 (as seen in the front view drawing)?
The profile tolerance around the slot is 0.50 mm or 0.25 mm. The dimensions of the ‘perfect’ slot
are 5 mm  12 mm. The dimensions of the smallest rectangle will be 4.75 mm  11.5 mm which
gives an area of 54.625 mm.
10. What is the virtual size of hole #1?
The virtual size of a hole is the diameter of a circle that is positioned at the ‘perfect’ location which is
guaranteed to be free space. If hole #1 is made at MMC (12 mm), the position tolerance is 0.25
mm. The virtual size will be equal to (12 – 0.25) = 11.75 mm. The virtual size will be the same
if the hole is made with any diameter within its limits of size since the position tolerance is specified
at MMC.