Tolerance Calculations
Basic Hole System
Tolerances
The Basic Hole System of calculating tolerances is based on using standard
reamers, broaches, and other standard tools to produce holes. Shafting is
machined to any size desired. The minimum hole size is taken as the basic size
and tolerances are applied to both the shaft and hole.
Given the following specifications find the limit dimension for both the shaft and
the hole using the “Basic Hole System”
Nominal size
2.0000
Fit
RC8
Tolerances
Using the American National Standard Running and Sliding Fits table cross
reference the nominal hole size (2.00) with the Standard Limits values (RC8)
Tolerances
Using the American National Standard Running and Sliding Fits table cross
reference the nominal hole size (2.00) with the Standard Limits values (RC8)
Hole
Shaft
+4.5
-6.0
-0
-9.0
Tolerances
Convert the numbers to thousands by moving the decimal point 3 places to the
left or dividing the numbers 1000.
Hole
Shaft
+0.0045
-0.0060
-0.0000
-0.0090
Tolerances
Add or subtract the values to the nominal size to find the upper and lower
limits dimensions of the hole and shaft
Hole
2.0000
2.0000
Shaft
2.0000
+0.0045
-0.0000
-0.0060
-0.0090
2.0045
2.0000
1.9940
1.9910
2.0000
The limits dimension for the hole diameter is (2.0000-2.0045) and the limits
dimension for the shaft is (1.9910-1.9940).
Tolerances
The minimum allowance is the difference between the smallest hole and
the largest shaft.
Minimum Allowance
2.0000
-1.9940
0.0060
Smallest Hole
Largest Shaft
Minimum Allowance
Tolerances
The maximum allowance is the difference between the largest hole
and the smallest shaft.
Maximum Allowance
2.0045
-1.9910
0.0135
Largest Hole
Smallest Shaft
Maximum Allowance
Tolerances
Limits of Clearance
Metric System of Tolerances and Fits
Metric System of Tolerances and Fits