GD&T Symbol Guide
Spherical Radius
Indicates the radius value applies to a spherical feature.
Definition
Spherical radius is the radius version used for spherical rather than planar circular features.
The symbol is shown as SR before the size dimension.
Application
Use SR for ball ends, domes, spherical pockets, and other sphere-derived surfaces.
Use spherical diameter when the spherical feature is defined by full diameter instead.
Spherical Radius Drawing Use
Spherical Radius is read with the adjacent dimension, note, or feature control frame so inspection uses the intended feature definition.
3D Tolerance Zone
This symbol defines or modifies a size, shape, or manufacturing dimension rather than creating a GD&T tolerance zone by itself.
Inspection Method
Read the symbol with the attached dimension, note, or feature control frame before evaluating the feature.
Verify the controlled feature using the drawing's stated limits, datum setup, and any special notes tied to the symbol.
Worked Read: Spherical Radius
A drawing includes the Spherical Radius symbol with a related feature requirement.
Identify
SR
Recognize the Spherical Radius symbol and the feature it modifies.
Read
Adjacent value
Use the attached dimension, note, or frame cells as the controlling requirement.
Inspect
Per drawing
Measure the named feature using the specified interpretation rather than assuming a generic size check.
Spherical Radius clarifies how the feature is defined so the drawing and inspection method stay aligned.
Comparison Table
| Item | Controls | Typical Placement |
|---|---|---|
| Spherical Radius | Dimension interpretation | Next to a dimension, note, or frame |
| GD&T control | Geometric variation | Feature control frame |
| Datum reference | Measurement setup | Datum feature or frame cell |
Notes
This page is part of the drawing-symbol reference set rather than a standalone geometric tolerance category.
When the symbol modifies a feature control frame, read it together with the tolerance value and datum references.