ANSI STANDARD LIMITS AND FITS CALCULATOR

ANSI standard limits and fits calculator was developed to calculate tolerances of inner and outer features of journal bearings, linear bearings, thrust bearings, bushings, ball bearings, roller bearings, housings, cylinder bores, drilled holes, linear and precision shafts, pistons, etc. The calculator works in line with ANSI B4.1-1967 (R2004) standard which is based on inch units. According to the input parameters of nominal size and fit type selection among running and sliding [RC], locational clearance [LC], locational transition [LT], locational interference [LN], force and shrink [FN] fits, size limits for hole/shaft are calculated. The schematic representation of the fit is also drawn. This calculator is applicable to non-threaded cylindrical parts.

Limits of sizes that calculated are the extreme values, within which the actual size of the dimension shall lie, at the standard temperature of 20C or 68F.

Limits and tolerances for shaft & hole fit

Calculator:

INPUT PARAMETERS
Parameter Value Unit
Nominal Size Inch
Fit Type Fit Detail

Note : Use dot "." as decimal separator.

 


RESULTS
HOLE
Parameter Value Unit
Hole Tolerance --- ---
Hole Upper Deviation --- thou(0.001 inch)
Hole Lower Deviation --- thou(0.001 inch)
Maximum Hole Size --- inch
Minimum Hole Size --- inch
SHAFT
Parameter Value Unit
Shaft Tolerance --- ---
Shaft Upper Deviation --- thou(0.001 inch)
Shaft Lower Deviation --- thou(0.001 inch)
Maximum Shaft Size --- inch
Minimum Shaft Size --- inch
FIT
Parameter Value Unit
Fit Type --- ---
Maximum Clearance --- thou(0.001 inch)
Minimum Clearance --- thou(0.001 inch)




Definitions:

Nominal size: The size of a feature of perfect form as defined by the technical drawing.

Deviation: The difference between a size and the corresponding nominal size.

Upper deviation: The difference between the maximum limiting size and the corresponding nominal size of a feature.

Lower deviation: The difference between the minimum limiting size and the corresponding nominal size of a feature.

Tolerance: The difference between the maximum and minimum size limits of a part.

Clearance Fit: A fit type where clearance exists between assembled parts under all tolerance conditions.

Interference Fit: A fit type where interference exists between assembled parts under all tolerance conditions.

Transition Fit: A fit type where clearance or interference can exist between assembled parts depending on tolerance conditions.

Hole Basis Fit System: A fit system in which hole lower deviation is zero. In other words the lower limit of size of hole is equal to nominal size. The required fit (clearance, interference etc.) is obtained by keeping hole as defined and applying various tolerance classes to shaft.

Allowance:  The difference between the maximum material limits of mating parts. Minimum clearance (+ allowance) or maximum interference (- allowance) between parts depending on the fit type.

GD&T A means of dimensioning and tolerancing a part with respect to relationship and function of that part. GD&T is used to define how a part feature relates the other part features in the same part or in a mating part; it’s a way to dimension and tolerance with respect to part’s function, the way it works.

Supplements:

Link Usage
Interference (press & shrink) fit calculator The calculator which calculates press fit force, required temperatures for shrink fit, fit stresses and other parameters necessary for interference fit design
Preferred Limits and Fits for Cylindrical Parts (Inch) Preferred limits and fits given in ANSI B4.1-1967 (R2004) standard are summarized
Precision Measuring Tools For Shaft and Hole Measurements Devices that can be used for the measurement of the inside diameter of the hole and outside diameter of a shaft

Reference:
  • ANSI/ASME B4.1 - 1967 (R2004) Preferred Limits and Fits for Cylindrical Parts