Coding Classification of Bore and Outside Diameter

When required for selective assembly or other reasons, bores and/or outside diameters may be classified into coded size groupings within the tolerance range specified in this chart. Methods of measuring and determining classification size are specified in ABMA Standard, Section 12.1, and 12.2. Complete code designation consists of the bore code as the first digit or letter, and the outside diameter code as the second digit or letter. When only one dimension is classified, the other is denoted by “0”.

Table of Coding Classification Tolerance Ranges 

*Measurement in inches.

Examples

“C12” Bore falls between 0.00000 & -0.00010, O.D. falls between -0.00010 & -0.00020
“CAB” Bore falls between 0.00000 & -0.00005, O.D. falls between -0.00005 & -0.00010
“C10” Bore falls between 0.00000 & -0.00010, O.D. is not coded