Guitar Setup Tools

Guitar Setup Tools

Choose an understring or fretboard radius gauge

Choose the gauge for the surface you need to check, then compare the exact radius markings and access on your instrument.

Identify the contact surface

A fretboard radius describes curvature across the board. Understring gauges are designed to compare the arc beneath the strings. Choose the reference surface and measuring location from the procedure for your guitar.

Compare the actual radius values

Read the radii supplied on the individual pieces before ordering. Two sets can have the same number of gauges but cover different markings. Check the width of the gauge as well as the stated radius.

Check how the board changes along the neck

A fixed radius stays the same along the board. A compound board changes radius. Follow the instrument maker’s setup method for the bridge and measure at the relevant point instead of treating one fretboard value as universal.

Source documentation

Guide questions

Is radius measured from the side?

It describes curvature across the width of the board or string array, at a particular location along the neck or bridge.

Does the action gauge read radius?

It reads individual string height. A radius gauge compares the curve across multiple strings or across the fretboard.

Does a 9-piece set tell me the included radii?

Read the marked values for the set. Count alone does not identify the radii.

Which accessory suits the job?

  1. The four radius gauges compare curvature across the supported string span. The action ruler measures the height at a single string and fret location.

    StewMac Standard Understring Radius Gauges, Set of 4 ↗MusicNomad MN602 String Action Gauge ↗

  2. The two StewMac sets have the same stated standard width. The four-piece option covers four specific radii; the nine-piece set adds intermediate markings.

    StewMac Standard Understring Radius Gauges, Set of 4 ↗StewMac Standard Understring Radius Gauges, Set of 9 ↗

Accessories in this guide

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