What is h8 tolerance on a shaft?

H8 tolerance on a shaft refers to a specific fit classification in the ISO system, indicating a standard for the allowable deviation in the shaft's diameter. The "H" signifies that the tolerance is based on the basic size and is a hole-based system, while the "8" designates the tolerance grade, with tighter tolerances indicated by lower numbers. Typically, an H8 tolerance provides a clearance fit, allowing for easy assembly and movement with corresponding components, usually used in applications where precision is important but some play is acceptable. The exact dimensions for H8 depend on the nominal size of the shaft.