Locking nut assembly for a guitar

Abstract

A finger operated locking nut assembly for a stringed instrument is provided including a baseplate for separating and maintaining the strings over the fretboard, a locking block for pressing the strings against the baseplate and a cam action lock screw. The lock screw provides a first, unlocked position for allowing the strings to slide for tuning of the instrument and a second, locked position for maintaining the tune of the instrument during play. The preferred lock screw includes a threaded body to allow rough adjustment and a transverse head bifurcating a pivoting lever tab to define spaced cams. These cams provide spaced contact points across the block for even pressure and secure locking of the strings.

I claim: 
     
       1. A locking nut assembly for retaining the strings of a guitar or the like at a constant tension over the fretboard and operable by finger pressure, comprising: a baseplate located adjacent the top of the fretboard, said baseplate providing a base for said strings for tensioning;   a plurality of locking blocks overlying said baseplate; and   cam action lock means for providing pressure to said locking blocks against said strings, said lock means including a cam lever having a first, unlocked position to allow the tuning of the instrument and a second, locked position to .[.proivde.]. .Iadd.provide .Iaddend. the clamping pressure to said locking blocks, whereby to allow the strings to be retained at a constant tension and in tune during play and quickly released for retuning.   
     
     
       2. The locking nut assembly disclosed in claim 1, wherein said baseplate includes a plurality of slots for receiving the strings. 
     
     
       3. The locking nut assembly disclosed in claim 2, wherein said slots are each V-shaped defining an included angle of substantially sixty degrees. 
     
     
       4. The locking nut assembly disclosed in claim 1, wherein each locking block retains at least a pair of strings at a constant tension. 
     
     
       5. The lock nut disclosed in claim 1, wherein threaded inserts are provided that may be adjustably positioned within said base plate, said threaded inserts receiving said cam action lock means and allowing adjustment of the angular orientation of said cam action lock means for easier actuation. 
     
     
       6. The locking nut disclosed in claim 5, wherein said threaded inserts each include a means for locking said insert in position within said base plate. 
     
     
       7. The locking nut disclosed in claim 6, wherein said insert locking means includes a nylon plug that bears against said base plate. 
     
     
       8. The locking nut disclosed in claim 1, wherein said baseplate is mounted to the guitar by means of self-tapping threaded inserts and machine screws. 
     
     
       9. A locking nut assembly for retaining a string of a guitar or the like at a constant tension over the fretboard and operable by finger pressure, comprising: a baseplate located adjacent the top of the fretboard, said baseplate providing a base for said string for tensioning;   a locking block overlying said string and said baseplate; and   cam action lock means for providing pressure to said locking block against said basplate, said lock means including a rotatable shaft passing freely through said block and lockingly engaging said baseplate and a cam lever pivotally mounted on the end of said shaft, said cam lever having a first, unlocked position to allow the tuning of the instrument and a second, locked position to provide the clamping pressure between said locking block and baseplate, whereby to allow the string to be retained at a constant tension and in tune during play and quickly released for retuning.   
     
     
       10. The locking nut assembly disclosed in claim 9, wherein the rotatable shaft is a screw and threadedly engages said base plate to allow a rough adjustment of the locking pressure. 
     
     
       11. The locking nut disclosed in claim 9, wherein the head of said screw includes a pivot pin transverse to the screw threads and said cam lever defines spaced cams for evenly distributing the cam force across said block. 
     
     
       12. The locking nut disclosed in claim 11, wherein said cam lever includes a wedge-shaped tab operable by finger pressure, said lever tab pivoting about said pivot pin off center with respect to a radius defined by said cams, said radius being substantially constantly increasing during actuation of said lever. .Iadd. 
     
     
       13.  In a musical instrument having a fretboard, string, a tuning peg, and string nut means mounted on said instrument at a location between the end of said fretboard and said tuning peg, said string nut means being engaged by said string the improvement comprising: a string locking assembly for retaining said string at a constant tension over said fretboard and operatable by finger pressure, said assembly comprising:   (a) support means mounted on said instrument at a location between said string nut means and said tuning peg, said support means defining a string support surface for engagement by a portion of said string;   (b) a locking block relatively movable with respect to said string support surface for clamping said string portion against said string support surface;   (c) hand-tightenable means to effect force on said string portion between said locking block and said string support surface, said hand-tightenable means by itself, when hand tightened, not achieving force sufficient to clamp said string portion adequately to accure prevention of longitudinal movements thereof; and   (d) hand-operable means, including a lever and a cam means, to effect a holding force on said string portion between said locking block and said string support surface, said hand operable means being hand operable from a release position to a locked position, said hand operable means having a mechanical advantage large in comparison to that of said hand tightenable means so that operation thereof to said locked position achieves force sufficient to clamp said string portion adequately and assure prevention of longitudinal movements thereof. .Iaddend. .Iadd.   
     
     
       14.  The invention of Claim 13 wherein said string nut means and said support means include a common baseplate. .Iaddend. .Iadd.15. The invention of Claim 13 wherein said hand-tightenable means includes a hand-turnable threaded fastener means with a hand-turnable transverse head portion. .Iaddend. .Iadd.16. The invention of Claim 13 wherein said hand-operable means includes a shaft passing through said locking block and said cam means and lever are pivotally mounted on the end of said shaft. .Iaddend. .Iadd.17. The invention of Claim 13, wherein said hand-operable means to effect a holding force on said string portion includes a cam element movable for relatively displacing said locking block and said string support surface for clamping said string portion, said cam element being movable by said lever. .Iaddend. .Iadd.18. The invention of Claim 17 wherein said movable cam element is a contoured cam having a contour which increases from a small size to a relatively large size. .Iaddend. .Iadd.19. The invention of Claim 18 wherein said hand-tightenable means (c) includes a hand-turnable threaded fastener means with a hand-turnable transverse head portion, said contoured cam engages said head portion, and increasingly larger portions of said contoured cam are moved between said head portion and said locking block as said hand-operable means (d) is moved from said release position to said locked position. .Iaddend. .Iadd.20. In a musical instrument having a fretboard, string, a tuning peg, and a string nut mounted on said instrument at a location between the end of said fretboard and said tuning peg, said string nut being engaged by said string, the improvement comprising: a string locking assembly for retaining said string at a constant tension over said fretboard and operable by finger pressure, said assembly comprising:   (a) support means mounted on said instrument at a location between said string nut and said tuning peg, said support defining a string support surface for engagement by a portion of said string;   (b) a locking block relatively movable with respect to said string support surface for clamping said string portion against said string support surface;   (c) hand-tightenable mechanism, including a hand-turnable threaded body, to effect force on said string portion between said locking block and said string support surface, said hand-tightenable mechanism by itself, when hand tightened, not achieving force sufficient to clamp said string portion adequately to assure prevention of longitudinal movements thereof; and   (d) hand-operable mechanism, including a lever and a cam element, to effect a holding force on said string portion between said locking block and said string support surface, said hand-operable mechanism being hand operable from a release position to a locked position, said hand-operable mechanism having a mechanical advantage large in comparison to that of said hand-tightenable mechanism so that operation thereof to said locked position achieves force sufficient to clamp said string portion adequately and assure prevention of longitudinal movements thereof. .Iaddend.   
     
     
        .Iadd.  .  The invention of Claim 20 wherein said string nut and said support have a common baseplate. .Iaddend. .Iadd.22. The invention of Claim 20 wherein said hand-tightenable mechanism includes a hand-turnable threaded body with a hand-turnable transverse head portion. .Iaddend. .Iadd.23. The invention of Claim 20 wherein said hand-operable mechanism includes a shaft passing through said locking block and said cam element and lever are pivotally mounted on the end of said shaft. .Iaddend. .Iadd.24. The invention of Claim 20 wherein said hand-operable mechanism to effect a holding force on said string portion includes a cam element movable for relatively displacing said locking block and said string support surface for clamping said string portion, said cam element being movable by said lever. .Iaddend. .Iadd.25. The invention of Claim 24 wherein said movable cam element is a contoured cam having a contour which increases from a small size to a relatively large size. .Iaddend. .Iadd.26. The invention of Claim 25 wherein said hand-tightenable mechanism (c) includes a hand-turnable threaded body with a hand-turnable transverse head portion, said contoured cam engages said head portion, and increasingly larger portions of said contoured cam are moved between said head portion and said locking block as said hand-operable mechanism (d) is moved from said release position to said locked position. .Iaddend. .Iadd.27. In a musical instrument having a fretboard, strings, tuning pegs, and string nut means mounted on said instrument at a location between the end of said fretboard and said tuning pegs, said string nut means being engaged by said strings, the improvement comprising: a string locking assembly for retaining said strings at a constant tension over said fretboard and operable by finger pressure, said assembly comprising:   (a) support means mounted on said instrument at a location between said string nut means and said tuning pegs, said support means defining a string support surface for engagement by a portion of each of said strings;   (b) locking blocks relatively movable with respect to said string support surface for clamping said string portions against said string surface; and   (c) cam action lock means operable by finger pressure to effect holding forces on said strings between said locking blocks and said string support surface, said cam action lock means including a movable lever and a cam means, said lever having a first, unlocked position to allow tuning of a string, and a second, locked position wherein said cam surface effects clamping pressure on a locking block, whereby to allow said string portions to be retained during play of said instrument and quickly released for retuning. .Iadd.28. The invention of Claim 27, wherein each of said cam action lock means includes a cam element movable for relatively displacing said locking block and said string support surface for clamping said string portion, said cam element being movable by said lever. .Iadd.29. The invention of Claim 28, wherein said movable cam element is a contoured cam having a contour which increases from a small size to a relatively large size. .Iaddend. .Iadd.30. The invention of Claim 29, wherein each of said cam action lock means includes a shaft with a transverse portion, said contoured cam engages said transverse portion, and increasingly larger portions of said contoured cam are moved between said transverse portion and said locking block as said lever is moved from said unlocked to said locked position. .Iaddend. .Iadd.31. In a musical instrument having a fretboard, strings, tuning pegs, and a string nut mounted on said instrument at a location between the end of said fretboard and said tuning pegs, said string nut being engaged by said strings, the improvement comprising:   a string locking assembly for retaining said strings at a constant tension over said fretboard and operatable by finger pressure, said assembly comprising:   (a) support mounted on said instrument at a location between said string nut and said tuning pegs, said support defining a string support surface for engagement by a portion of each of said strings;   (b) locking blocks relatively movable with respect to said string support surface for clamping said string portions against said string surface; and   (c) cam action lock means operable by finger pressure to effect holding forces on said strings between said locking blocks and support surface, said cam action lock mechanisms each including a movable lever and a cam element, said lever having a first, unlocked position to allow tuning of a string, and a second, locked position wherein said cam surface effects clamping pressure on a locking block, whereby to allow said string portions to be retained during play of said instrument and quickly   
     
     
        released for retuning. .Iadd.32.  The invention of Claim 31, wherein each of said cam action lock mechanisms includes a cam element movable for relatively displacing said locking block and said string support surface for clamping said string portion, said cam element being movable by said lever. .Iadd.33. The invention of Claim 32, wherein said movable cam element is a contoured cam having a contour which increases from a small size to a relatively larger size. .Iaddend. .Iadd.34. The invention of Claim 33, wherein each of said cam action lock mechanism includes a shaft with a transverse portion, said contoured cam engages said transverse portion, and increasingly larger portions of said contoured cam are moved between said transverse portion and said locking block, as said lever is moved from said unlocked to said locked position. .Iaddend.