The Guitar Notched Straight Edge accurately checks the neck straightness & fretboard flatness independent of the frets.

There are 4-versions of universal notched straight edge available from the webstore:

1)  24" to  27" Guitar Scale - With Precision Straight Edge

2)  24" to  30" Guitar- Baritone

3)  27" to  34" Baritone - Bass

4)  30" to  38" Bass



The unique design of the notch spacing allows the tool to be used on an infinite number of guitar scales within the range quoted.

For example on the 24"-27" option, any scale length that falls between 24” and 27” (610mm-686mm) will be catered for. This includes over 20 popular scales including Gibson, Fender, PRS, Gretsch and the following:  24", 24.5", 24.5625", 24.625", 24.75", 24.84", 24.9", 25.0", 25.34", 25.4", 25.5", 26", 26.25", 26.5", 27", 630mm, 635mm, 640mm, 645mm, 650mm, 660mm & 670mm. Multiscale guitars can also be checked.

The tool has 18 notches. The design of the tool is based on only checking the length of the fretboard that is capable of being deflected. The very highest frets are omitted as these are past the heel/neck join and won't be affected by truss rod adjustment or string tension.


The positioning on the neck will vary depending on the scale of the instrument. A double dot mark for position reference is provided on the tool. The dots are positioned at the 12th notch.

For shorter scales, the tool is used with the dots placed at the 11th fret on the guitar and for longer scales the dots are placed at the 13th fret.



A removable steady prevents the tool from toppling over, allowing it to remain positioned on the neck during setup and adjustments. Free-standing use provides easy observation of changes to neck when adjusting the truss rod. (The steady can be used with or without strings fitted).



  • Combining 1) & 3)  will provide a scale range of 24" to 34" (610-864mm) - including a precision straight edge.

  • Combining 2) & 4) will provide a scale range of  24" to 38" (610-965mm).

Universal Notched Straight Edge | GMC Luthier Tools