Tolerance Calculations

Basic Shaft System

TolerancesThe basic shaft system of calculating tolerances is based on using standard shafting. Holes are then machined to any size desired. The minimum shaft 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 Shaft 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

TolerancesConvert 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

TolerancesReverse the values and the sign of the hole and shaft. 

Hole Shaft

+0.0045 -0.0060

-0.0000 -0.0090

Hole Shaft

+0.0060 -0.0045

+0.0090 +0.0000

TolerancesAdd or subtract the values to the nominal size to find the upper and lower limits dimensions of the hole and shaft

 

Hole Shaft

 

The limits dimension for the hole diameter is (2.0060-2.0090) and the limits dimension for the shaft is (1.9955-2.000).

2.0000 2.0000

+0.0060 +0.0090

2.0060 2.0090

2.0000 2.0000

-0.0045 +0.0000

1.9955 2.0000

TolerancesThe minimum allowance is the difference between the smallest hole and the largest shaft.

Minimum Allowance 2.0060 Smallest Hole

-2.0000 Largest Shaft

0.0060 Minimum Allowance

TolerancesThe maximum allowance is the difference between the largest hole and the smallest shaft.

 

Maximum Allowance 2.0090 Largest Hole

-1.9955 Smallest Shaft

0.0135 Maximum Allowance

Tolerances

Limits of Clearance