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Publication numberUS1727230 A
Publication typeGrant
Publication dateSep 3, 1929
Filing dateMay 23, 1927
Priority dateMay 23, 1927
Publication numberUS 1727230 A, US 1727230A, US-A-1727230, US1727230 A, US1727230A
InventorsCox John E P
Original AssigneeCox John E P
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Finger board for stringed musical instruments
US 1727230 A
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Description  (OCR text may contain errors)

Sept. 3, 1929- J. E. P. cox 1,727,230




Application filed May 23, 1927. Serial No. 193,597.

This invention relates to stringed instruments and has especial relation to guitars or other fretted instruments usually played by the Spanish method of pressing the strings upon the frets to produce a desired note or chord.

An object of the present invention is to provide a stringed instrument which in addition to providing means whereby it may be played in the manner above stated, may also be played as a steel guitar, the instrument being especially adapted for students and others who have not mastered the art of operating the steel bar.

Another object of the invention is the provision of a fretted instrument in which the frets may be selectively moved to engage the strings, instead of pressing the strings down upon the frets, together with means to pre vent false vibration of the strings as the frets are moved into and out of contact therewith.

With the above and other objects in view, the invention further includes the following novel features and details of construction, to be hereinafter more fully described, illustratcd in the accompanying drawings and pointed out in the appended claims.

In the drawing illustrating my invention:

Figure 1 is a representation of a finger board of a stringed musical instrument embodying my invention.

Figure 2 is a vertical section through half of the finger board.

Figure 3 is an isometric projection of the under side of the finger board.

Figure his a cross section on the plane 44 of Figure 1, showing the vertical adjustment of the fret.

Figure 5 is a similar view with the fret raised to the plane of the strings.

Referring now in particular to the drawings, 1 represents a finger board of a stringed instrument provided as usual with a plurality of tuning pins 2 to effect tension of the strings and accurately tune them. 3 represents a group of frets mounted at spaced distances along the finger board, by which in the usual form of construction the finger may be pressed against the string to vary the note of the string. 1 represents a group of strings which may be properly tuned by the adjusting devices 2. 5 represents a fret which may be metallic or any other rigid material, the upper edge 6 of which lies transversely to the strings and is adapted to form an abutment against which they may be fretted to modify the note of the string.

The frets 5 of the present invent-ion instead of being stationary are vertically movable. Their upper edges are spaced below the strings and in playing the instrument after the manner of a steel guitar, the steel bar is dispensed with and the frets are selectively moved upward into proper contact with the strings to produce the same efi'ect as the steel bar.

For this purpose. the frets extend into the neck of the instrument below the finger board through slots 1 provided in said board. Each fret, which is in the form of a plate, is adapted to be moved outwardly through the action of a slide 7 and is yieldingly held against outward movement through the medium of a spring 11 suitably anchored to a block 12. The fret 5 has projecting there through spaced pins 8 and these pins are adapted to ride upon inclined edges 7 provided in the slide 7. A rod 9 projects through the neck at one side and is provided with a knob 10 by which the slide may be quickly shifted. One of these slides is provided for each fret, as indicated in Figure 1, and the slide plates are adapted to readily shift upward, being controlled by the rod 9 and the knob 10.

When desired, the instrument may be played by pressing the strings downward upon the frets in the usual manner, or, the frets may be selectively moved into engagement with the strings to provide the same effect as bringing a steel bar into engagement with the strings when playing a steel guitar.

In the use of the steel bar, the hand of the player is brought into contact with the strings prior to bringing the steel bar into such contact, and after the strings have been picked or set in vibration, the steel bar is first disengaged and subsequently the hand. This is necesssary in order to eliminate false vibration of the strings due to their contact by the steel bar while the strings are relatively slack or loose. This false vibration is overcome in the present invention by providing a strip 6 of relatively soft material and which is carried by or set into a groove in the upper edge of each fret. This strip may be and preferably is of vulcanized soft rubber but any other suitable material may be utilized. The strip extends only a slight distance above the upper edge of-the fret and when a. fret is forced outward. the strip 6 will first contact with the strings so that when the strings are placedunder proper tension to produce the desired tones, there willbe no false vibration when they engage the upper edge of the fret. Due to the character of the strip 6, the strings will be temporarily embedded therein so as to contact with the edge of the fret as shown in Figure 5 of the drawings. As the fret is lowered, its metallic edge first disengages from the strings and as the latter are still embedded in the rubber strip 6 no false vibration is permitted during this movement.

It will be thus seen that movement of the frets into and out of contact with the strings will produce the same character of tones produced by the player when using the steel bar, the operation of the bar being mechanically instead of manually effected.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is: p

'1. In a stringed musical instrument, movable frets spaced along the neck of the instrument and normally disposed below and out of contact with the strings, and means to selectively move the frets substantially at right angles to and into contact with the strings.

2. In a stringed musical instrument, a neck having spaced transversely disposed openings therein, slide plates disposed within the openings and extending slightly above the top surface of the neck and defining frets, and means to slide the frets outward to engage the strings.

3. In a stringed musical instrument, a neckhaving spaced transversely disposed openings therein, plates disposed within the openings and extending slightly above the top surface of the neck and defining frets, a slide plate for each fret, means extending laterally from each slide to move said slide transversely of the neck, and means extending from the plates and engaging the slide plate versely of the neck, pins extending from the I slide plate, and cam portions provided in the slide plate to engage the pins and move said plates outward when the slides are moved transversely.

in testimony whereof I aifix my signature.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3469489 *May 27, 1968Sep 30, 1969Barth CarlSystem of movable frets for stringed musical instrument
US4297936 *Apr 9, 1980Nov 3, 1981Mouton Martin JRetractable fret system for stringed instruments
US4722260 *Oct 1, 1986Feb 2, 1988Gabriele PigozziStringed musical instrument having retracting frets
US4777858 *Apr 14, 1986Oct 18, 1988Petschulat David JAdjustable string contact system for a musical instrument
US5325757 *Sep 11, 1992Jul 5, 1994Serban GheneaFret retractable neck for stringed musical instruments
US8153874Mar 21, 2011Apr 10, 2012Randall Eric StockwellStringed musical instrument convertible between fretted and fretless playing configurations
EP0801781A1 *Jul 1, 1994Oct 22, 1997Serban GheneaFret retractable neck for stringed musical instruments
U.S. Classification84/314.00R, 984/115
International ClassificationG10D3/00, G10D3/06
Cooperative ClassificationG10D3/06
European ClassificationG10D3/06