Why use this annotation?
Keep a fixed geometric limit when a larger hole or smaller pin should not permit additional location error.
DATUM / MODIFIER GUIDE
REGARDLESS OF FEATURE SIZE
Regardless of feature size (RFS) means the geometric tolerance remains fixed throughout the allowed size range. Under ASME Y14.5-2018, it is the default for an applicable tolerance when no MMC or LMC modifier follows the value. The circled S found on some older drawings is obsolete; no RFS symbol is added to a current frame.
INTERACTIVE APPLICATION
Regardless Of Feature Size: drawing and interpretation
DRAWING CALLOUT
Read the annotation
For the Ø10.1 ±0.1 hole, permitted sizes are Ø10.0–Ø10.2. Position remains Ø0.2 at every permitted size because no MMC or LMC modifier follows the tolerance value. Primary datum A and secondary datum B establish the illustrated boxed basic location.
Key points
RFS is the default for applicable geometric tolerances when neither MMC nor LMC is specified. Changing size does not create bonus tolerance.
INTERPRETATION
Ø0.2 position tolerance applies at every permitted size
The actual hole is Ø10.1, within its Ø10.0–Ø10.2 size limits. The dashed purple circle is a section through the fixed cylindrical position zone; it constrains the hole axis, not the hole diameter. The small zone is enlarged for clarity.
Point to note
RFS is the default for applicable geometric tolerances when neither MMC nor LMC is specified. Changing size does not create bonus tolerance.
Where is it applied?
Precision locating bores and features where consistent alignment matters more than extra clearance allowance.
How to apply and read the annotation
Drawing callout
Steps to add it to a drawing
- Specify the hole size limits independently of the geometric tolerance.
- Write position Ø0.2 without an MMC or LMC modifier.
- Reference primary A and secondary B and define the boxed basic location.
- Evaluate position against the same Ø0.2 limit at every allowed size; check size separately.
How to read it
For the Ø10.1 ±0.1 hole, permitted sizes are Ø10.0–Ø10.2. Position remains Ø0.2 at every permitted size because no MMC or LMC modifier follows the tolerance value. Primary datum A and secondary datum B establish the illustrated boxed basic location.
RFS is the default for applicable geometric tolerances when neither MMC nor LMC is specified.
ASME Y14.5-2018 (R2024)
ASME Y14.5 generally defaults to RFS when no material condition modifier is shown.
ASME Y14.5 edition reference. Examples are learning schematics; use the complete requirements on the drawing.
LEARN BY DOING
Practise GD&T on engineering drawings
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