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Rhode Island residents Chester P. Keefe and John C. Navilliat recognized the troubles associated with worn fretwire and the cost and time as...

Interchangable Frets in 1965

Rhode Island residents Chester P. Keefe and John C. Navilliat recognized the troubles associated with worn fretwire and the cost and time associated with replacing the frets with brand new wire. They invented a new method of installing frets which involved easily replaceable inserts.

Their patent, US-3273439A, was filed in 1965 and granted in 1966
https://patents.google.com/patent/US3273439A/


Illustration of the design

"The fingerboard is that part of a fretted stringed instrument on which the frets are placed. It is usually made of wood and may or may not be of one piece with the neck of the instrument. Frets are those devices which are positioned on the fingerboard perpendicular to the long axis of the fingerboard with such proper spacing as to effect the desired pitch of the string or strings when fingered in the proper manner for playing the fretted stringed instrument. The frets are usually made of metal and usually inserted into slots cut into the wooden fingerboard for this purpose and held there by friction. When the frets become worn or damaged or otherwise need replacement, they must be pried out of the wooden fingerboard and a new fret inserted into the slot which previously held the fret being replaced. This is a task which requires much time and skill to perform. Also with each replacement of a fret in the same slot, the slot becomes less able to hold the fret with proper friction due to the resulting enlargement of the slot.

In general: The object of this invention is to provide a device or devices which facilitates the replacement of a fret or frets, quickly and easily on a fretted stringed instrument without causing damage to the fingerboard.

In particular: An object of this invention is to provide a device in the fingerboard of a fretted instrument which accommodates a removable fret thereby facilitating the changing of frets without damage to the fingerboard, said device being made of such suitable material as will resist wear such as plastic or metal."

These inserts would be held in place either with screws or adhesive and would be easy to replace if an instrument needed new fretwire. Radiused slots in the fretboard could also be used to hold the inserts in by friction and most importantly conform to the radius of the fingerboard.

Navilliat passed away in May of 2018, followed 6 days later by Keefe. As far as I can tell, their sole patent never made its way onto production instruments and I am unable to find any examples of their work.

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