US3437000A - Mounting string plates in musical instruments - Google Patents

Description

' April 8, 1969 s. w. GOODLANDER 3,437,000

I MOUNTING STRING PLATES IN MUSICAL INSTRUMENTS Filed Aug. 19. 1966 I NVE N TO R infill/5L 14- 60001 Ill/DEE ATTORNEYS BY and Z2,

United States Patent 3,437,000 MOUNTING STRING PLATES IN MUSICAL INSTRUMENTS Samuel W. Goodlander, Mason, Ohio, assignor to D. H. Baldwin Company, Cincinnati, Ohio, a corporation of Ohio Filed Aug. 19, 1966, Ser. No. 573,519 Int. Cl. G10c 3/08 U.S. Cl. 84-188 7 Claims ABSTRACT OF THE DISCLOSURE A string plate mounted in predetermined spaced relation to a supporting frame by means of bolts which are in threaded engagement both With the string plate and the supporting frame, temporary supports being employed to initially establish the predetermined spaced relation of the string plate relative to the supporting frame, Whereupon the bolts are set and thereafter serve to support the spring plate in fixed spaced relation to the supporting frame.

This invention has to do with the mounting of string plates in the cases of stringed musical instruments. While the instant invention may be utilized in any string instrument in which a string plate is mounted in spaced relation to a case or supporting frame, it Will be described in an exemplary embodiment as having to do with grand pianos.

A modern grand piano is normally composed of an action (which includes the keys, the hammers and the associated mechanical parts effective to actuate the hamrners when the keys are struck), a soundboard, strings, a string plate to which the opposite ends of the strings are fastened so as to hold the strings stretched at the proper tension and to position them in the proper relationship with respect to the soundboard and other parts of the instrument, and a case into which all of the previously mentioned parts are fitted. The soundboard, the strings and the string plate normally occupy parallel planes. The piano case is normally composed of an outer rim of substantial depth having the familiar shape of a grand piano. An inner rim of lesser depth but similarly shaped is attached to the inside of or made an integral part of the outer rim. Various frame members extend both longitudinally and transversely of the case to reinforce the frame and support the various parts of the instrument. The soundboard is usually secured about its periphery to the inner rim of the case, excepting for its forward edge portion which is secured to a transverse frame member of approximately the same depth as the inner rim.

In order for the vibrational energy of the strings of the piano to reach the soundboard and to produce the best tonal effect, the strings are normally coupled to the soundboard by means of one or more bridge elements fixedly secured to the soundboard. The strings, which are stretched upon the string plate, pass across the top surface of one or the other of the bridges and are connected to it, usually by being deflected around pairs of nail-like pins driven into the tops of the bridges. The strings must not press down too hard upon the top surfaces of the bridges; neither must they pull away from the bridges. It therefore becomes important for the strings and the string plate to which they are attached to be spaced at precisely the correct distance from the top surface of the soundboard.

Whereas most other parts of a piano are normally made of wood, the string plate, in order to be strong enough to sustain the forces imposed upon it by the stretched strings, is normally made of metal, usually cast when the string iron. While the string plate is normally quite heavy, the soundboard is made of wood and is normally relatively light in weight. In a modern concert grand piano, for eX- ample, the soundboard and bridge assembly may weigh about 25 pounds, whereas the string plate may weigh as much as 400 pounds. Even if it were not for the great Weight of the string plate, attachment of the string plate directly to the soundboard would be undesirable because the soundboard must be free to vibrate in accordance with the energy imparted to it by the strings. The string plate therefore is normally mounted to the piano case by means of screws passing through clearance holes in the flanged peripheral edges of the plate and thence into the inner rim of the case. In order to correctly position the strings with respect to the bridge and at the same time prevent the marginal edges or flanges of the string plate from resting directly upon the marginal edges of the soundboard-which is usually made of wood so soft that the weight of the plate might crush itit has been the practice in the past to set dowels into the inner rim of the case, the dowels projecting upwardly and being of a height such that the string plate is supported on them. Thus, pairs of spaced dowels are installed in the inner rim at intervals around the periphery of the plate, and the plate itself is held against the tops of the dowels by lag screws passing through holes in the edges of the plate and turned into the portions of the inner rim which lie between the pairs of dowels. This method of setting a string plate presents a number of difficulties most of which result from the fact that the plate castings themselves, being large and heavy, lack uniformity of thickness and degree of flatness from casting to casting. If the undersurface of the peripheral portions of a plate is rough or uneven, or if the plate is slightly warped, it will not properly engage the top ends of the dowels when set in position. Under these circumstances, the tightening of the lag screws mentioned above may cause bending of the plate and even breakage in some instances. Exact fitting of each dowel to the bottom surface of the plate is difficult and time consuming because the points of contact between the undersurface of the plate and the dowels are inaccessible and essentially hidden after the plate has been lowered into the case. Even if the undersurface of the plate is dressed or machined about its periphery so as to lie in a predetermined plane or planes, it is nonetheless extremely diflicult to insure that the top ends of the dowels will lie in the same plane or planes plate is set into position. Even if this could be insured, a variation of the thickness of the casting may cause the strings, which are fastened to the upper surface of the plate, to lie in the wrong plane.

In contrast to the foregoing, it is a principal object of the instant invention to provide a way of mounting string plates which is simpler, less laborious, and more precisely controlled, as well as more economical than the modes of mounting plates heretofore devised.

A further object of the invention is the provision of improved means for mounting a string plate above and in spaced relationship to the frame of a piano and particularly to the inner rim of a grand piano.

A further object of the invention is the provision of means for mounting plates which obviate the use of dowels and the necessity for adjusting the height of the dowel tops either by using dowels of differing lengths or dowel-receiving holes of differing depth.

Still a further object of the invention -is the provision of plate supporting means which automatically adjust to the correct elevation to precisely fit the string plate at each point of support.

The foregoing together with other objects of the invention which will be set forth hereinafter or which will be apparent to one skilled in the art upon reading this specification, are accomplished by that structure and arrangement of parts and in that procedure of which the aforesaid exemplary embodiment will now be described.

Reference is made to the accompanying drawings wherein:

FIGURE 1 is a plan view of a grand piano case with the top removed, showing the relationship of the case, soundboard and string plate of a typical instrument.

FIGURE 2 is an enlarged fragmentary sectional view taken along the line 2-2 of FIGURE 1.

In FIGURE 1 there is shown a grand piano having an outer rim 1, and inner rim 2 and a string plate 3. The string plate is a cast iron structure of a form in current use in grand pianos. There are string plates of modified shapes also in use in the art, and the invention is applicable to them as well. Some plates have peripheral portions following the contour of the inner rim 2 throughout its entire length. Peripheral portions of the string plate 3 are generally formed with holes 5 for the passage of the means for fastening the plate to the inner rim of the piano.

The manner in which the string plate is atlixed to the front portion 6 of the piano case may differ in different constructions. It 'will be understood that there is combined with the front portion 7 of the string plate a pin block (not shown) underlying the portion 7 which receives the tuning pins for the piano strings. In one type of grand piano structure the pin block is afiixed to the front portion 7 of the plate by screws or bolts passing through the holes 8 in the string plate. The pin block is in turn secured to one or more of the frame members forming a part of the case.

In other piano constructions the pin block may be mounted to the string plate as above described; but it may be desired to mount the string plate in such a way that both it and the pin block are separated from the underlying frame structure. For example, in certain pianos the pin block is associated with the string plate in such a way that they need not be dissociated when the string plate is removed from the piano case for replacement, adjustment or repair. In such an instance (assuming that the pin block is fastened to the string plate by screws passing through the holes 8) and assuming that it is desired so to mount the string plate in the piano case that a peripheral spacing will exist at all points between the string plate and either the sounding board or the frame of the piano, holes such as the holes 8a and 8b may be treated in the way hereinafter set forth to effect the desired spacing.

The specific nature of the invention will best be appreciated by reference to FIGURE 2 wherein the soundboard 9 is shown attached to the inner rim 2, with the string plate 3 of the piano supported in a position above the level of the soundboard 9. In accordance with the invention the holes 5a in the string plate will be tapped or threaded for the acceptance of a bolt, such as the bolt 10 indicated in FIGURE 2. When the string plate has been placed within the outer rim of the piano, a series of holes (one of which is shown at 11 in FIGURE 2) is drilled into the upper surface of the inner rim 2. This is preferably done by passing a powered drill bit through the holes 5a in the string plate, or through corresponding holes in a template having arrangements to locate the holes in the inner rim at positions corresponding to holes in the string plate. The diameter of the drill bit will be such as to pass through the holes 5a without destroying the threads therein. Consequently, the hole 11.have a diameter effectively smaller than the outside diameter of the threaded shank of the bolt 10. The hole' 11 can, if desired, be drilled entirely through the depth of the inner rim 2, but this is not necessary where the projection of the shank of the bolt into the inner rim is less than the depth of the inner rim.

The hole 11,in the inner rim may be threaded if desired; but, in many instances it is possible and preferable to allow the threaded bolt shank 10 to cut its own threads in the hole 11. While the holes 11 have been shown as pass- 4 ing through the soundboard, it is possible in many constructions to limit the periphery of the soundboard so that the holes will be formed in the inner rim only. Especially in the event the bolt shank 10 is to cut its own threads in the inner rim member 2, it may be found advantageous to taper the end portion of the bolt shank 10, as at 10a, to facilitate its entry into the hole 11.

The installation of the string plate proceeds as follows: The required height of the string plate above the soundboard is determined. The plate, positioned within the confines of the outer rim, is blocked up to the proper height at the rear of the piano case, e.g. at the point marked A in FIGURE 1. If the front portion of the string plate rests upon the pin block, which in turn rests upon the front portion 6 of the piano case, blocking at other points may not be found necessary. Otherwise the string plate is also blocked up to the proper height above the front portion 6 of the piano case at two interspaced points, eg at B and C. The plate now rests with its peripheral portions which contain the holes "5a (and in some instances its front portion which contains the holes 8) lying respectively above the inner rim and the rear edge of the front portion 6 of the case. The desired plate level will be determined either by a support or block at the point A and by the tuning pin block (or wrest-pin plank) or by additional blocks at the points B and C, depending upon the construction as hereinabove explained. The holes 5a in the plate lie respectively above the holes 11 which have been drilled into or through the inner rim. Alternatively, instead of utilizing supporting blocks to establish the desired plate level, screws may be set in the inner rim and frame at the points A, B and C, the tops of the screws being positioned at the desired height of the plate with the plate resting on the tops of the screws.

The plate is now fastened in position by threading the bolts 10 through the holes 5a and into the inner rim 2 as illustrated. It will be understood that as the bolts are rotated by a tool engaging the bolt head (such as the hexagonal head 12 shown in FIGURE 2), the bolt shank end first passes through the threaded opening in the plate and then passes downwardly until it encounters the soundboard 9 or the hole 11 in the inner rim. Continued rotation of the bolt will cause its end to enter the hole 11, either engaging in precut threads therein or cutting its own threads as above explained. Further rotation of the bolt 10 is stopped when the bolt head 12 engages the peripheral portion of the plate 3. A Washer 13 may, if desired, be placed on the bolt shank before the bolt is turned into the threaded opening in the plate. It will be understood that the mass of the plate prevents the bolts from lifting the plate relative to the inner rim rather than biting into the wood surrounding the holes 11, and consequently the rotation of the bolts will'cause them to be drawn into the holes until their heads seat against the plate.

If a pin block is united with the string plate and it is desired to support both the edge of the plate and the pin block in spaced relationship to the frame of the piano, it is contemplated by the invention that the holes 8a and 8b illustrated in FIGURE 1 would be threaded or tapped in the same manner as holes 5a, the string plate being held in place by counterparts of the bolts 10, as will be readily understood by the skilled worker in the art. These counterparts of the bolts 10 may or may not pass through the underlying pin block depending upon the specific construction.

This method of installing the string plates of pianos is rendered possible by the fact that the normal rib construction of such plates prevents excessive sagging of the plates when supported at least at the points A, -B and C. The several bolts 10, installed as described, support the plate at the proper height without exerting any bending stress on the plate. Since the bolts are threaded into the plate,

1 they can be turned no further than is permitted by their respective heads. Thus, the bolts may be installed by power tools, because it is impossible to turn the bolts too far. The bolts do not serve as adjusting means for the plate height, this being determined by the blocks or other supports at points A, B and C. The bolts simply serve as supports for the plate. When the bolts have been installed the supporting blocks may be left in place or removed, as desired.

The term blocks as used herein should be construed in the broad sense. While it is feasible to employ carefully dimensioned blocks of wood or other substances suitably resistant to compression, it is also possible to use adjustable mechanical supports, inclusive of the aforementioned plate supporting screws.

The manner in which the soundboard is fitted into the case does not constitute a limitation on the invention, but it is normally done in the absence of the string plate. When mounted in the way herein taught, the string plate is out of contact with the soundboard and may be, and preferably is, out of direct physical contact with the outer rim of the piano case. It is supported in the proper position throughout at least most of its periphery by a plurality of the bolts 10. The use of dowels and their rather cumbersome adjustment is thus entirely eliminated, and the installation of the string plate is simplified and rendered less laborious and costly.

While the invention has been described in connection with the peripheral support of a string plate, it will be understood that in piano construction where various frame members lie opposite non-peripheral portions of the plate, the same principles may be applied to the use of additional or supplementary supporting bolts.

Modifications in the invention may be made without departing from the spirit thereof. For example, while a preference has been expressed for headed bolts (or screws) which will seat against the plate, bolts or screws without heads may be employed. For example, so-called socket-screws which incorporate a turning means having a diameter no greater than the outside diameter of their threads may be used to support the plate, although care must be exercised to insure that such screws will not be turned too far.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a musical instrument having a string plate and a frame portion with respect to which said string plate is to be fixedly mounted in predetermined spaced relationship, the improvement which consists in a plate mounting comprising threaded bolts engaged in threaded holes in portions of said string plate, said bolts each having a portion extending freely beyond the said string plate, the extending ends of said bolts being threaded into holes in said frame portion with intermediate portions of said bolts extending between said string plate and said frame portion, 'whereby said bolts serve to support said string plate in a predetermined fixed position spaced from said frame portion.

2. The structure claimed in claim 1 wherein said bolts have heads overlying said string plate, and wherein said heads are seated against said string plate.

3. In a grand piano having an outer rim and an inner rim, together with a string plate having peripheral portions overlying portions of the inner rim, the improvement which consists in a string-plate mounting comprising threaded bolts threaded into holes in the said peripheral portions of the string plate, extending freely intermediate their lengths below the said string plate by a predetermined fixed distance, and having their opposite end portions threaded into holes in said inner rim, whereby said bolts serve to support said plate in a predetermined fixed position above said inner rim.

4. The structure claimed in claim 3 wherein said bolts have heads overlying said string plate, and wherein the final rotative position of said bolts is determined by the effective engagement of their heads against the peripheral portions of the said string plate.

5. A method of mounting string plates in spaced relationship to frame portions in musical instrument, the method comprising temporarily supporting a string plate in a predetermined fixed position spaced from said frame portions, providing threaded holes in said plate opposite said frame portions, providing coaxial holes in said frame portions opposite the holes in said plate, threading bolts into the holes in said plate, and turning the said bolts to set them so that intermediate portions thereof extend freely beyond said plate with opposite end portions thereof in threaded engagement in the holes in said frame portions, whereby to permanently mount said plate in said predetermined fixed position.

6. The process claimed in claim 5 wherein the spaced relationship of said plate and said frame portions is initially established by blocking means positioned to support said plate in said predetermined fixed position relative to said frame portions, said blocking means serving as temporary supports for said plate until said bolts are set, said bolts being turned until the elfective lengths of their intermediate portions extending between said string plate and said frame portions are substantially equal to the spacing between the string plate and frame portion as established by said blocking means.

7. A method of mounting string plates in the cases of grand pianos, which cases have an outer rim and an inner rim, the process comprising the steps of forming a series of threaded holes in peripheral portions of a string plate, which portions overlie said inner rim, temporarily supporting the said string plate at interspaced points within the said case so that it lies in predetermined spaced relationship to said inner rim, passing through said threaded openings a drill smaller in outside diameter of said threaded plate openings so as to form holes in said inner rim, and threading headed bolts into said threaded openings in said string plate and into the holes in said inner rim until the opposite ends of said bolts engage in the holes in said inner rim and the heads of said bolts effectively engage said string plate, whereby said bolts become the effective means for permanently supporting said string plate in predetermined spaced relation relative to said frame.

References Cited UNITED STATES PATENTS 1,575,668 3/1926 Weiser 84-187 1,752,676 4/1'930 Loitsch 84-184 2,648,245 8/ 1953 Russell 84185 RICHARD B. WILKINSON, Primary Examiner.

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