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Advanced Fret-slot Cutting Technique

Overview

When stringed-instrument luthiers add CNC routing capabilities to their set of fabrication tools, more often than not it is to replace the onerous task of hand cutting fret-slots. The convenience and improved accuracy that can be realized with moderately priced CNC based systems, in addition to the ability to easily cut blind slots and the complex geometries of so-called "True Temperament" frets are rapidly making these semi-automated systems essential additions to a commercial shop.

Cutting fret-slots requires the use of small diameter cutters that belong to a class known as "microtools". Although there is no agreement in the industry as to what constitutes a microtool, it is generally agreed that any cutter with a diameter less than or equal to 0.0313" (0.8mm) is "micro" enough to require special handling. To that end, there are a number of new skills that need to be learned and shop practices that should be added.

Before proceeding, please take a few minutes to read our article on the First Steps for Machining Wood with Microtools.

All of the tools needed to implement these techniques can be found on the Tools for Musical Instrument Makers page.

An excellent video demonstration of this new fret-slotting method (and a lot more) has been released by David Wieland at Dark Art Guitars. The processes shown in this video make it required viewing for anyone just getting started using CAD/CAM/CNC to make musical instruments or if you want to improve your existing techniques and practices.