Regardless of feature size (RFS) means a geometric tolerance stays the same whatever size the feature is made within its limits: no bonus tolerance. Under current ASME Y14.5 it is the default whenever no M or L modifier is shown, so you rarely see a symbol for it.
RFS is what you get when the feature control frame has no modifier after the tolerance. A bearing bore with position Ø0.02 and no M must be within Ø0.02 at every size from the smallest to the largest. Nothing is gained by making the bore bigger.
Choose RFS where the feature locates something precisely, such as bearing bores, dowel holes, gear centres and press fits. Bonus tolerance would let the axis wander when the hole is big, which matters for those even though it would not stop a bolt passing through.
Datum references without a modifier are likewise applied at RMB (regardless of material boundary): the datum simulator expands or contracts to the actual datum feature, so there is no datum shift.
RFS does not change the zone shape of the control. It keeps the zone the same size at every feature size.
On a chart of allowed tolerance against feature size, RFS is a flat line, compared with the sloping lines of MMC and LMC.
RFS is a material condition, not a control, so it has no datum of its own. A datum reference with no modifier is applied at RMB.
| Modifier | With regardless of feature size (rfs) |
|---|---|
| Symbol | None on current ASME drawings. Older drawings may show a circled S, which meant the same thing. |
| Applies to | Every geometric tolerance on a feature of size when no M or L is shown, and always to runout, concentricity and symmetry. |
Example: a Ø10.0–10.2 mm hole with position Ø0.1 to datum A and no modifier
Result: The hole fails. The same part would pass with Ø0.1 at MMC (allowed Ø0.28).
Under current ASME Y14.5 practice (since the 1994 edition) RFS applies by default, so the circled S is not used. Drawings made to the 1982 edition and earlier may show it, and in that older edition position tolerances needed an explicit M, L or S.
Every GD&T symbol page: GD&T symbols chart
Yes. Under current ASME Y14.5, a geometric tolerance with no M or L applies regardless of feature size.
It is the old RFS symbol, found on drawings made to the 1982 edition of ASME Y14.5 and earlier. It means the same as no modifier on a current drawing.
When the feature locates something precisely, such as a bearing bore or dowel, where extra movement at larger sizes would hurt function.
No. The tolerance is the same at every size within the limits.
Regardless of material boundary: the datum equivalent of RFS. A datum letter with no modifier is applied at RMB, so the datum simulator fits the actual feature and there is no datum shift.
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