How to Measure and Reduce Tool Runout

This post is a 9-page visual storyboard (same format as the T-401 and Cylindrical vs. Centreless posts). Insert the matching PNG from the runout-measurement image set using the editor's image button, then delete each placeholder line.

1. Hero

How to Measure and Reduce Tool Runout

2. Why It Matters

Excess runout shows up as poor finish, uneven tool wear, and parts that drift out of tolerance — often long before anyone traces it back to the spindle.

3. Mount the Indicator

Mount a dial test indicator on a magnetic base against the spindle or tool holder before taking any reading.

4. Read the Gauge

Rotate the spindle or tool slowly by hand and watch the needle sweep — the total swing is your runout reading.

5. Record Readings

Check more than one point along the tool's length and log each reading so a trend is easy to spot over time.

6. Tolerance Table

Illustrative tolerance ranges, not a substitute for your tool or machine manufacturer's specification.

7. Inspect the Collet

A worn or debris-packed collet is one of the most common sources of runout — inspect it before assuming the spindle itself is at fault.

8. Common Causes

A quick reference for where runout usually comes from and where to check first.

9. Work With Apar

Extra Precision Universal Workhead Fixture · Straight Workhead Fixture · T-600 Tool & Cutter Grinding Machine