Week 7

Question 1

when does minimum possible clearance (tightest) occur in a shaft and hole

Answer 1

hole is at its smallest and shaft is at its largest

Question 2

when does maximum possible clearance (loosest) occur in a shaft and hole

Answer 2

hole is at its largest, shaft is at its smallest

Question 3

metric unilateral format for tolerance dimensioning

Answer 3

35 +0.05 (always positive)
0 (no sign on zero)

Question 4

imperial unilateral format for tolerance dimensioning

Answer 4

.500 +.005
-.000

no zeroes before decimal, signs on both upper and lower limits. sigdigs on all numbers, including zero

Question 5

metric and imperial equal bilateral formatting for tolerance dimensioning

Answer 5

metric:
35+- 0.05
(no sig digs on nominal number)

imperial:
.750 +- .005
(sigdigs on nominal number match tolerance. no zero before decimal on nominal number)

Question 6

metric and imperial unequal bilateral formatting for tolerance dimensioning

Answer 6

metric:
35 +0.25
-0.10
(same sigdigs on both limits, no sig digs on nominal number)

imperial:
1.000 +.008
-.010
(same sigdigs on both limits, also sig digs on nominal number)

Question 7

metric and imperial limit formatting for tolerance dimensioning

Answer 7

metric:
35.05
35.00
(same sigdigs on both limits)

imperial:
.250
.248
(same sigdigs on both limits)

Question 8

general rule for imperial vs metric tolerancing formats

Answer 8

metric: nominal never has sigdigs and always has a zero before the decimal

imperial: nominal always has sigdigs and never has a zero before the decimal

Question 9

unilateral tolerance format purpose

Answer 9

the hole/shaft may be larger than the the nominal but not smaller or vice versa.

one tolerance is 0

Question 10

how to calculate variation between features for chain dimensions

Answer 10

sum of the variations of intermediate segments

Question 11

how to calculate variation between features for baseline dimensions

Answer 11

sum of variations on the two dimensions from their origin to the two features

Question 12

conventional tolerancing of pins or holes method + when does it work/fail

Answer 12

square tolerance zones

if the pin is in contact with ONLY the x axis or y axis of the hole it will work (against either side of the square)

if the pin is in contact with both the x and y axis of the hole (corner of the square) it will fail

Question 13

tolerance

Answer 13

variation in size acceptable in manufacture, while ensuring the functional fit requirements of the product

Question 14

allowance + when its required

Answer 14

required where a specific fit condition is required between mating surfaces

min. stated clearance or max. stated interference

Question 15

nominal (basic) size

Answer 15

the dimension assigned in CAD as the perfect form

Question 16

deviation

Answer 16

the algebraic difference between the actual size and the basic size

Question 17

upper deviaion

Answer 17

the algebraic difference between the maximum limit and the corresponding basic size

Question 18

clearance + when we use it + what it results in

Answer 18

refers to the mating of cylindrical parts such as a bolt and hole when we want
shaft < hole

always results in motion

Question 19

interference

Answer 19

for mating cylindrical parts in which we want
shaft > hole.

relative motion between shaft and hole is impossible

Question 20

fundamental deviation

Answer 20

the magnitude of offset of the tolerance zone from the nominal

Question 21

fits + 3 types

Answer 21

relationship between external feature of size and internal feature of size

1. clearance fit
2. interference fit
3. transition fit

Question 22

tolerance

Answer 22

the difference between the max and min size limits of a part

Question 23

hole basis

Answer 23

represents a system of fits corresponding to a basic hole size. more typically used

Question 24

shaft basis

Answer 24

represents a system of fits corresponding to a basic shaft size. used when provided a premade shaft

Question 25

are holes capital or lowercase

Answer 25

capital

Question 26

are shafts capital or lowercase

Answer 26

lowercase

Question 27

lower limit shorthand

Answer 27

EI

Question 28

upper limit shorthand

Answer 28

ES

Question 29

standard tolerance value shorthand

Answer 29

IT

Question 30

For a hole, how to get ES and EI

Answer 30

ES = EI + IT EI and IT from table

Question 31

for a shaft, how to get ie and es

Answer 31

ei = es - IT es and IT from table

Question 32

IT

Answer 32

standard tolerance value (min required clearance/interference between shaft and hole)

Question 33

hole basis ststem

Answer 33

hole is the standard with zero fundamental deviation and the shaft size is varied to suit hole

Question 34

why do we use hole basis more often

Answer 34

easier to machine a shaft to specific size than a hole

Question 35

shaft basis + when it is used + ex

Answer 35

fundamental deviation (IT) of the shaft is zero hole made to suit the shaft used when the shaft is the standard used when it may be necessary to mount several parts with holes having slightly different deviations on a single shaft without maching the shaft

Question 36

equation for clearance

Answer 36

hole size - shaft size

Question 37

"upper and lower limits of size"

Answer 37

find the min and max clearance

Question 38

how to interpret numbers in tolerance specification ratio

Answer 38

smaller number is a tighter tolerance. bigger number is requires less tolerance