MACHINE HEAD FOR TUNING A STRINGED INSTRUMENT, ESPECIALLY A GUITAR OR THE LIKE

Abstract: A machine head, especially for precision tuning of a guitar string or strings, avoids the slackness between the cog and worm gear drive of the existing design which can give rise to tuning slip and unprecise tuning. The proposed machine head has a spindle to which a string is secured at one end and carries an arm (2a). Adjusting means (3) cooperates threadingly with an abutment (7) and the end of the adjusting means bears on the arm whereby rotation of the adjusting means determines the position of the arm and hence tension in the string.

Description: Title: Machine head for tuning a stringed instrument, especially a guitar or the like DESCRIPTION This invention relates to a machine head for tuning a stringed instrument especially a guitar or the like. Traditionally the guitar string is tensioned and tuned using a 'machine head 1 which consists of a vertical spindle which can be rotated by means of a worm gear-cog assembly. The 'machine head' is fixed to the head of the guitar and the string is fed through a hole in the spindle and is wound onto it using the worm gear-cog system. The string is thus tensioned as the other end is fixed immovably at the body end of the guitar. Tensioning continues until the right musical note is sounded. The drawback of the traditional system is that slackness between the cog and the worm can cause tuning slip and unprecise tuning. It has been accepted without question that a worm drive is required to provide sufficient adjustment and consequently the above system has become universally accepted for guitars or the like despite the short comings. It is an aim of the present invention to provide a machine head which overcomes the short comings. According to one embodiment of the present invention there is provided a machine head for a stringed instrument, such as a guitar which can be fitted to a guitar for purposes of tensioning and so tuning up a guitar string. The string is passed round and secured to a spindle (preferably vertical). The spindle can be rotated by means of a screw which pushes on a curved arm that is attached to the spindle. The say lateral (relative to a guitar head) movement of the screw is converted to rotational movement by means of this arm so that it is possible to rotate the spindle through about a quarter of a turn (90 degrees arc of rotation). The section of the spindle that the string goes round is of sufficient circumference (in the order of 25mm - 35mm) so that the slack can be taken out of the string and stretch allowed for so that the string can attain the required tension within the adjustment allowed. A number of machine head assemblies can be mounted on a common carrier. Accordingly, the present invention also provides a machine head for a multi stringed instrument comprising for each string a rotatable spindle and screw threaded adjusting means therefor acting between an arm of the spindle and an abutment therefor, and wherein the abutment for two or more adjusting means is carried by a commmon carrier adapted to be secured to the instrument head. Contrary to the accepted understanding a quarter of a turn provides quite sufficient adjustment facility so enabling the worm-cog system to be dispensed with. Of course it would be feasible to incorporate a one way ratchet over into the arm/spindle drive train to allow for take up of excess slack, although I have found this to be completely unnecessary. This tuning system permits more precise tuning than the traditional system and the tuning is more stable as the device is unable to detune as it is stopped against the tuning screw. Tension in the string urges the arm against the adjusting screw to maintain the setting. A lock nut or other locking system cold be incorporated if desired. The screw action provides much finer tuning as four turns of the screw is equivalent to one of the traditional system. A specific embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:- Figure 1 shows a side view of the system (one string only shown by way of example); Figure 2 shows a top view of the system (backplate shown as dotted line) demonstrating the adjusting screw pushing on the curved arm; figure 3 shows the underneath view as in Figure 2; Figure 4 and Figure 5 demonstrate how the sleeve (with curved arm) moves by the action of the adjusting screw; Figure 6 shows a guitar with the tuning system fitted (one string only shown); and Figure 7 is an underneath view illustrating six machine head assemblies mounted on a common carrier. Referring to the drawings, the invention is described by way of example with reference to the preferred application, namely as a guitar machine head, although it will be appreciated that it could be used for other stringed instruments. The machine head comprises a backplate 4 which is fitted to the reverse of tiie guitar head 14. A bearing surface (sleeve bearing 16) is attached to the backplate and is inserted into a hole in the guitar head (see Figure 1). A spindle 1 passes through the bearing surface in relation to which it is journalled, and has a wider end uppermost. A sleeve 2 (with curved arm 2a) is slipped over the other end of the spindle 1 and is secured to it by means of a split pin 5 which passes through a hole common to both the spindle and the sleeve (see Figure 5). The curved arm 2a of the sleeve rests against an adjusting screw 3 which passes through a threaded mounting 7 which is conveniently carried on the backplate 4. The arm 2a has a curved surface 2b and the adjusting screw 3 has a curved end 3a which engages said curved surface. To string and tune the guitar the following proceedure is adopted. With the adjusting screw fully slackened off the string 6 is tensioned as much as possible by hand, then wound round the top end of the spindle and passed through a hole 18 in the top of the spindle then nipped under a loop of the string. The adjusting screw 3 is then adjusted to push on the sleeve arm 2a (Figures 4 and 5). The rounded head of the adjusting screw follows the curve XY (see Figures 4 and 5) which is so designed that the curve is tangential to the screw at whatever position the screw is in. The system rotates anti-clockwise and puts the string under tension. The top end of the spindle is of such a diameter that all the adjustment required is accommodated in a quarter of a turn of the spindle (90 degrees arc of rotation). The string can then be adjusted up to concert pitch and tuning adjustments can be made as required by slackening or tightening the screw. Figure 6 shows how the string is fixed to the body end of the guitar, passed over the bridge up to the nut and hence to the tuning mechanism. It will be understood that the back plate could carry several spindles and adjusting means and Figure 7 describes one possible example from which it will be seen that the back plate 4' carries six string spindles with associated arms 2a' and respective adjusting screws 3' threaded through respective abutments 7'.

Claims: CLAIMS 1. A machine head for fitting to a stringed instrument for the purpose of tensioning and so tuning up a string, the machine head comprising a spindle to which the string is secured and which is rotatable by screw threaded adjusting means acting between an arm of the spindle and an abutment therefor. 2. A machine head as claimed in claim 1 in which the screw threaded adjusting means engages threadingly with the abutment and a free end of the adjusting means engaging with said arm. 3. A machine head as claimed in claim 2 in which the arm has a curved surface for engagement tangentially by free end of the adjusting means. 4. A machine head as claimed in claim 1 or 2 in which the free end of the adjusting means presents a curved surface to the arm. 5. A machine head as claimed in any one of claims 1 to 4 in which the arm is securable fixedly to the spindle. 6. A machine head as claimed in any of the preceding claims in which the end of the spindle to which the string is secured has a circumference of 25mm to 35mm. 7. A machine head as claimed in any one of the preceding claims in which the spindle has a hole adjacent one end to accommodate the string in securing thereof to the spindle. 8. A machine as claimed in any one of the preceding claims in which the abutment is carried by a plate which is adapted for fixing to the instrument head guitar head. 9. A machine head as claimed in claim 8 in which the plate has a sleeve bearing in which the spindle is ournalled. 10. A machine head constructed and arranged and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 11. A machine head for a multi stringed instrument comprising for each string a rotatable spindle and screw threaded adjusting means therefor acting between an arm of the spindle and an abutment therefor, and wherein the abutment for two or more adjusting means is carried by a common carrier adapted to be secured to the instrument head. 12. A machine head as claimed in claim 11 in which the abutment for each adjusting means is carried by the common carrier. 13. A machine head as claimed in claim 11 or 12 in which the carrier accommodates respective bearing means for a complimentary number of spindles. 14. A stringed instrument when fitted with a plurality of machine heads according to any one of claims 1 to 10 or one or more of the machine heads according to any one of claims 11, 12 or 13. 15. A stringed instrument according to claim 14 in the form of a guitar or the like.

Inventors: GRANT JOHN DAVID, GRANT, JOHN, DAVID
Applicants: GRANT JOHN DAVID, GRANT, JOHN, DAVID
Application year: 1989
Main classification: G10D3
IPC codes: G10D3