What is RFS (Regardless of Feature Size)?

What is RFS (Regardless of Feature Size)?

• A. The tolerance is applied independent of the actual size of the feature.
• B. The tolerance is applied relative to the nominal size.
• C. The tolerance is applied with respect to a datum reference frame.
• D. The tolerance is modulated by material condition.

Answer: (A)

RFS means the specified tolerance does not change with the actual size of the feature. When a callout has no size modifier, the tolerance value is fixed and applied independent of whether the feature is larger or smaller than nominal. For example, a true-position tolerance of 0.5 is a constant allowance: the feature’s center must lie within a 0.5 diameter cylinder about the true position, regardless of the hole’s actual diameter. This is different from tolerances that are modulated by material condition (MMC/LMC) or by size; those would widen or tighten the tolerance as the feature size changes. The other options either imply dependency on nominal size, rely on datum relations in a way that isn’t what RFS defines, or describe modulation by material condition, which RFS explicitly does not do.

RFS means the specified tolerance does not change with the actual size of the feature. When a callout has no size modifier, the tolerance value is fixed and applied independent of whether the feature is larger or smaller than nominal. For example, a true-position tolerance of 0.5 is a constant allowance: the feature’s center must lie within a 0.5 diameter cylinder about the true position, regardless of the hole’s actual diameter. This is different from tolerances that are modulated by material condition (MMC/LMC) or by size; those would widen or tighten the tolerance as the feature size changes. The other options either imply dependency on nominal size, rely on datum relations in a way that isn’t what RFS defines, or describe modulation by material condition, which RFS explicitly does not do.