Device on a string tightener for stringed instruments
The present invention relates to a device for a string tightener for stringed instruments, consisting of a fixing peg for the string attached to the neck of the instrument, said fixing peg being rotatably attached by means of a self-locking worm. 
     Such tighteners are used for guitars, banjos, mandolins etc. 
     The fixing peg for the string mentioned at the beginning is normally provided with a hole or a slot into which the end of the string is threaded, and in order to lock the end, the peg is turned a few times, causing the string to be pulled around the peg a few times, thus locking the end. This leads to a couple of marked disadvantages, viz. principally, that the string is easily slackened a little when in use, thus becoming untuned because the mutual position on the string windings on the fixing peg may change. The second disadvantage is that the string will run across a relatively sharp edge, where it is threaded into the hole, which means that it will easily be subjected to extra strain at this point, so that it may break in this place after a while. 
     The present invention is intended to eliminate these disadvantages and give directions for an improved string tightener for stringed instruments. This is achieved according to the invention in that the free end of the peg is provided with a threaded section, which works in conjunction with a screw or nut, and in that a plane section running radially or a shoulder has been provided for clamping down the string, said shoulder acting in conjunction with a corresponding section on the screw or nut, or with the part that acts in conjunction with those. 
     In a preferred embodiment a distance bush has been provided on top of the plane section or shoulder on the peg. An advantageous embodiment is characterized in that the two surfaces working in conjunction on the peg and screw/nut have been worked so as to grip the string well, for instance by roughening. 
    
    
     In the following, the invention will be described in more detail with reference to the drawing, where 
     FIG. 1 shows a primary embodiment for a string tightener according to the invention, 
     FIG. 2 shows a second embodiment for the string tightener according to the invention, and 
     FIG. 3 shows how the string is attached to the string tightener according to the invention. 
    
    
     The string tightener consists of a box 1, which is intended for attaching to the instrument. In the box a worm 2 is mounted, having a handle 3. The worm passes into mesh with a worm gear 4, which directly drives the fixing peg 5 for the string 6. In the embodiment according to FIG. 1 a threaded neck 7 is provided on the upper end of the peg, working in conjunction with a nut 8 with a hexagon groove 9 to be operated by a spanner. 
     In the embodiment according to FIG. 2, the tightener principally consists of the same parts, however, here the fixing peg 5 is provided with a threaded hole 10, acting in conjunction with a screw 11. Between the screw head 12 and the upper plane section 13 of the peg 5, an intermediate piece 14 is provided. 
     In FIG. 3 it is demonstrated how the string is tightened by means of the string tightener according to the invention. One end of the string 6 is attached in the usual fashion to the resonance box of the instrument. The free end 6&#39; of the string is pulled by hand round the peg 7 or the screwed-in screw 11 and is tightened, while the screw 11 is tightened up. An approximately correct tightening of the string has now been achieved, and said string is held firmly but very gently between the two plane, parallel surfaces. By means of the handle 3 the peg 5 is then turned and the string is tuned. Normally only a fraction of a turn is necessary in order to tune the string correctly. Thus, there will not be any more windings around the peg 5, which can cause the string to lose tune. Nor is the string resting across a sharp edge, resulting in some typical points of wear leading to breaks. 
     The reason why it is advantageous to use a ring 14, is that the same angle of incidence may be attained for the strings to the metal string supporting ledge that is situated at the top of the finger board, and over which all the strings are deflected. By varying the height of the intermediate piece 14, the same angle of incidence is attained for the strings that are attached to a string tightener situated near the ledge, as for one that is situated further away. 
     One big advantage of the device according to the invention compared with string tighteners of the prior art, is that if the end of a string is put so that the string runs in the direction of the threads, a self-tightening and self-locking effect on the screw or nut will be obtained. In that way, a tightening up of the screw or nut occurs the more the string is stretched.