FIT TOLERANCES FOR PARALLEL / TAPER KEY - KEYSEAT ASSEMBLIES

ANSI B17.1 standard identifies two classes of stock for parallel keys. One is a close, plus toleranced key stock and the other is a broad, negative toleranced bar stock. Each is combined with appropriate keyseat tolerances to make assemblies. Based on the use of two types of stock, two classes of fit are given. Class 1 is a clearance or metal-to-metal side fit obtained by using bar stock keys and keyseat tolerances. This is a relatively free fit and applies only to parallel keys. Class 2 is a side fit, with possible interference or clearance, obtained by using key stock and keyseat tolerances as given in this page. This is a relatively tight fit.

Calculator:

INPUT PARAMETERS
Key Type
Fit Type
Key Cross Section
Nominal Key Size Width [over - to (incl.)]

 


RESULTS
Parameter Value Unit
Key Type --- ---
Fit Type ---
Key Cross Section ---
Key Width [over - to (incl.)] --- inch
SIDE FIT
Key Width Upper Deviation --- inch
Key Width Lower Deviation ---
Keyseat Width Upper Deviation ---
Keyseat Width Lower Deviation ---
Maximum Clearance ---
Minimum Clearance ---
TOP AND BOTTOM FIT
Key Depth Upper Deviation --- inch
Key Depth Lower Deviation ---
Shaft Keyseat Depth Upper Deviation ---
Shaft Keyseat Depth Lower Deviation ---
Hub Keyseat Depth Upper Deviation ---
Hub Keyseat Depth Lower Deviation ---
Maximum Clearance ---
Minimum Clearance ---

Definitions:

Keyseat: An axially located rectangular groove in a shaft or hub. Hub keyseat has been sometimes referred to as a keyway

Sunk Key: A standard form of key with rectangular or square cross-section in which the key fits into the keyseats on the shaft and the hub.

Reference:
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2016) . Machinery's Handbook . 30th edition.  Industrial Press Inc.
  • Oberg, E. , Jones ,F.D. , Horton H.L. , Ryffel H.H., (2012) . Machinery's Handbook . 29th edition.  Industrial Press Inc.
  • ANSI B17.1-1967, Keys and Keyseats