Technical Reference
277
Tables for Determining Metric Tolerances
Table 2: Commonly Used Hole-Basis System of Fits Table 2 shows closer detail on the hole-basis system of fits than Table 1. When using the hole-basis system of fits, the smallest diameter in the hole tolerance range is fixed to the zero line (basic nominal hole size or diameter), and the clearance between the shaft and hole extends below the zero line, or negative relative to the basic nominal hole size.
LETTER SYMBOLS AND GRADE NUMBERS OF SHAFTS
CLEARANCE FITS
TRANSITION FITS
INTERFERENCE FITS
BASIC HOLES
b
c
d
e
f
g 4 5 6 6 7
h 4 5 6 6 7 7 8
js
k 4 5 6 6 7
m n
p
r
s
t
u
x
4 5 6 6 7
4 5 6 6 7
H5
H6
6 6 7 7 8
6*
6* 6* 7*
6 7
6 7
6* 7*
6 7
6 7
6 7
6 7
H7
8 9 8 9
H8
9 8 9
8 9
H9
9 9
H10 9 *Exceptions occur in some steps of dimensions. 9
Table 3: Commonly Used Shaft-Basis System of Fits Table 3 shows closer detail on the shaft-basis system of fits than Table 1. When using the shaft-basis system of fits, the largest diameter in the shaft tolerance range is fixed to the zero line (basic nominal shaft size or diameter), and the clearance between the shaft and hole extends above the zero line, or positive relative to the basic shaft size.
LETTER SYMBOLS AND GRADE NUMBERS OF HOLES
CLEARANCE FITS
TRANSITION FITS
INTERFERENCE FITS
BASIC SHAFTS
B C D E
F
G H Js
K M N P R S
T
U X
5 6 6 7 7 8 8 9 8 9
5 6 6 7 7
5 6 6 7 7
5 6 6 7 7
h4 h5
6*
6
6 7 7 8 8
6 7 7
6 7 7
6* 7*
h6
7 7
7
7 7
7
7
7
7
7*
h7
8 9 8 9
8 9 8 9
h8
9
h9
10 10 *Exceptions occur in some steps of dimensions. 10
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