- Radial run-out = radial deviation of a rotating surface relative to the datum axis.
- Measured with a dial indicator/dial comparator — between centers or in a V-block.
- Critical for shafts, tools, and spindles.
What is radial run-out accuracy?
Radial run-out indicates how much a rotating surface deviates radially from the datum axis during one revolution. The smaller the deviation, the more smoothly and precisely the component runs.
Radial run-out vs. axial run-out
Radial run-out refers to the radial deviation perpendicular to the axis, while axial run-out refers to the axial deviation of an end face along the axis. Both are important parameters of rotating parts.
How is radial run-out measured?
The workpiece is held in a defined position — often between centers or in a V-block — and rotated about the datum axis. A dial indicator or dial comparator scans the surface; the difference between the highest and lowest reading is the radial run-out.
What should you look for in the evaluation?
What matters is a clean datum reference, the correct tolerance specification, and reproducible measuring conditions. Only a defined datum makes measured values comparable.
Frequently asked questions
What is the difference between radial run-out and axial run-out?
Radial run-out is the radial deviation perpendicular to the axis; axial run-out is the axial deviation of an end face along the axis.
What is radial run-out measured with?
With a dial indicator or dial comparator, while the workpiece is rotated about its datum axis in a defined position — for example, between centers or in a V-block.
