US1886864A - Piano - Google Patents

Description

W. G. BETZ Nov. '8, 1932.

yPIANO Filed May 6, 1951 Patented Nov. 8, 1932 PATENT OFFICE WILLIAM G. BETZ, OF HAMMOND, INDIANA PIANO Application filed May 6, 1931.

My invention relates in general to pianos. It relates more in particular to an improved method of and means for constructing and assembling the string plate, bridge and sounding board, particularly with respect to relative adjustments and positions of these members.

The conventional piano comprises a frame or case, usually constructed of wood, a sounding board secured usually by gluing to the case, and bridge secured to the sounding board, also usually by gluing. The string plate is disposed above the sounding board, in a grand piano) and supports the strings. The string plate includes a hitch pin section and a tuning pin section, the strings being stretched between the two sections and when so stretched or tensioned between the two sections they should have the proper relationship to the bridge to secure the best results.

These results must take into consideration the actual mechanical construction of the piano as well as the tone quality.

Since the bridge must have a definite relationship with the string plate, it has been customary heretofore to fit the bridge and sounding board to the string plate by a cut and try method to secure the proper proportions and relative position of the parts. This was done by initially assembling the sounding board and bridge, placing it on the case, placing the string plate in position and then by suitable means measuring the relationship between the top of the bridge and the string plate. Usually ample material was left so that if anything, the bridge would be found to be too high, so that the wooden parts could then be planed off either by planing the bridge itself, or also in unusual cases, by planing the sound board or the case. It is clear that with this method it took a considerable amount of time and the expenditure of considerable labor, to fit the sounding board to the string plate. In explanation, it might be said also at this time, that since the string plate is constructed of metal, customarily a casting, it is substantially impossible to obtain very accurate dimensions of parts. This is due partly to the fact that the castings are never entirely accurate, partly to the fact that the casting Serial No. 535,346.

must be machined in places and this is not always accurately controlled, and partly because due to uneven cooling, which cannot be entirely eliminated, some warping of the string plate takes place. To get the best tone results, the position of the strings must be very accurately controlled and so even a slight inaccuracy in the string plate must be compensated for in the practice heretofore employed by adjusting the sounding board and bridge thereto.

The principal object of my present invention is to improve the practice of piano construction by avoiding the diiculties herein above pointed out.

Another object is to adjust the string plate to the sounding board rather than adjusting the sounding board to the string plate.

Another object is so to construct a piano that the sounding board and bridge may be initially glued permanently into position on the case, and the string plate adjusted to the resulting sounding board and bridge construction.

Another object is the construction of the string plate which will permit the adjustment, of the position of 'the strings with respect to the bridge.

Another object is the provision of an improved method of assembling pianos.

Another object is the provision of a construction or method as outlined in previous objects which can be applied to either an upright or grand piano.

Other objects and features of the invention will be apparent from a consideration of the following' detail description taken with the accompanying drawing. wherein,

Fig. l is a plan view of a portion of a piano including the string plate, the invention being shown as applied to the treble string portion of a piano, and

Fig. Q is a sectional view taken along the lines .f-F2 of Fig. l.

According to the general features of the invention as suggested in preceeding paragraphs and in the objects, my invention consists in general in the provision of means whereby the string plate can be adjusted to the sounding board and bridge instead of adjusting the sounding board and bridge to the string plate. The drawing shows an einbodiinent of the invention as applied to a grand piano which accomplishes the objects of the invention in the manner described.

The drawing shows my invention applied to a standard type of grand piano having a sounding board l0, carrying a bridge ll, the sounding board being glued to the case, according to the usual practice, a portion of the case l2, being shown (Fig. The string plate is secured above the sounding board and above a pin block 13, which forms a part of the frame.

The string plate is cast in a single piece and cooperates with the sound board and bridge portion of the piano in such a way as to produce two string sections, a treble string section A, and a base string section B, the strings of the section B lying over the strings of the sectionA. The string plate has a treble tuning pin section 14 and a base tuning pin section 16, through which timing pins l? extend into the pin block 13. A treble hitch pin section 18, is provided' as Well as a base hitch pin section 19. The sectionsare secured together' and reenforced by ribs 21 so that all portions of the string plate, including the hitch pin sections and tuning pin sections constitute a single casting.

I shall now further describe the string plate and the invention as applied thereto in connection with the treble string section through which section 2*,2 shown in Fig. 2 is taken. lit will be understood that in genF eralthe description of the invention as applied. to the treble string section is the same as when applied to the base string section,

The hitch pin section comprises a double L shaped member 22, into which hitch pins 23 are secured. The top face 2261i of the hitch pin section of the double l. shaped member slants upwardly toward the bridge and a string adjusting member 2li lying on top of the slanting surface, is effective inra manner to be described, for adjusting the position of the strings with respect to the bridge 11. The strings `26 pass from the hitch pin section over the bridge Where they are held by agralfes, 27 under a down-bearing bar 28 and over an lip-bearig ridge 29 formed in the tuning pin section. The down-bearing bar and tip-bearing ridge are conventional construction in pianos but cooperate in the pres-- ent invention with other portions of the construction to secure a result never obtained. heretofore.

1When the piano has been assembled by securing the string plate section on top of the sounding board, it may be found ythat the strings, if `secured in their normal positions between the hitch pin and the tuning pin, will bear down too greatly on the top of the bridge, for example. Clearly this con-dition is impractical and it is impossible to obtain satisfactory tone from a piano if the strings ineet the bridge in this way. ly moving the adjusting member 24. however, as shown in dotted lines, the strings are brought up or Idown so as to occupy their proper positions with respect to the top of the bridge, and obtain ust the right tension on the bridge and sounding board.

It will be seen that due to the arrangement of the ribs a single nien'xbcr 24 does not extend the fulllength of the piano but is rather made up of sectional pieces. ln trueing up the piano it may be found a greater error exists in some places than in others and this is compensated for by swinging the member 24 to a slight so that one end will rest farther up on the incline than the other end. Similarly, one section 24 may be father up on the incline than the section 24I adjacent.

I have found that by `my present invention avery great deal of 'time and material. is saved in the production of the wooden poi tions of thepiano as the entire wooden portion can be manufactured to h ave definite dimensions and thestiing plate, after being as1 sembled, can in effect be adjusted to compen sate for inanufactu ing or other inaccuracies. Occ sionally a piano will give in some of its parts after it has been in use for some time. This is only the unusual case, but it can, and it does sometimes occur. ln practice heretofore it would usually be necessary to return such a piano to the factory iii-order to correct the trouble. An advantage of my invention is that no matter when the adjustment is re'- quircd, whether in course of manufacture, or, in anunnsual case, years after the manufacture, such adjustment is readily and easily accomplished. c Y

The shape given to the hitchpin member 22, gives it strength in the places where needed so that the strain produced by the strings is borne well under all circumstances, and also when the string plate is cast, there is less possibility of warping, with the resultant imperfections in construction and errors in the dierent dimensions. a

lnconsidering the advantages of the hitch pin section as herein described, I wish to point out that in prior constructions the hitch pin section of the plate has always been one of its weakest parts. This is because the hitch pin section is subjected to the greatest strain of the string tension. It has often been customary to employ bolts at frequent intervals along the hitch pin section to hold it tightly down, due to the fact that there is a tendency for it to bulge up and away from the sounding board when a strain placed on it. The use of bolts in this Way is not entirely satisfactory because the plate would still sometimes crack and there would be insutlicient string bearing on the bridge, With a resultant poorer tone. It must be remembered that poorer tone can be'caused lil@ by either too great a down-bearing by the strings on the bridge, or by too little down bearing. Hcretofore when hitch pin sections were bent to bulge they would not bulge uniformly so that some strings would bear down with a greater force on the bridge than other strings. This is very undesirable and leads to irregularity and improper creation of tone throughout. By the present invention the strings may be made to bear on the bridge with ust the right down-bearing pressure and with an even down-bearing pressure throughout all of the strings. In addition, with this construction there is a saving of material in the plate and the sounding board is more exposed thereby allowing freer tone.

What I claim as new and desire to protect by Letters Patent of the United States is l. In a piano, a sounding board, a bridge secured thereto, a string plate, means for securing the strings to the string plate, said strings passing over the bridge, and means on the string plate in addition to said securing means for regulating the pressure of the strings on the bridge.

2. In a piano, a sounding board, a bridge secured thereto, a string plate having a hitch pin section and a tuning pin section, one of said sections having a slanting surface, strings tensioned between hitch pins and tuning pin section, respectively, and string engaging means adjustable along said slanting surface for regulating the pressure of the strings on the bridge.

3. In a piano, a sounding board, a bridge secured thereto, a string plate having a hitch pin section and a tuning pin section, one of said sections having a slanting surface, strings tensioned between hitch pins and tuning pins carried by the hitch pin section and tuning pin section respectively, and a bar adjustable along the slanting surface and adapted to engage the strings to raise or lower the strings with respect to the bridge.

4. In a piano, a sounding board, a bridge secured to the sounding board, a string plate having a tuning pin section, and a hitch pin section having a slanting upper surface, hitch pins carried by the hitch pin section, tuning pins at the timing pin section, strings tensioned between the hitch pins and tuning pins and passing over the bridge, and string contacting means adjustable along the slanting upper surface of the hitch pin section so all. strings will have equal down-bearing on the bridge and indirectly on the sounding board.

5. In a piano, sounding board, a bridge secured to the sounding board, a string plate having a tuning pin section, and a hitch pin section having a slanting upper surface, hitch pins carried by the hitch pin section, tuning pins at the timing pin section, strings tensioned between the hitch pins and tuning pins and passing over the bridge, and a string adjusting rod lying along the slanting upper surface and adjustable along said surface.

6. In a piano, a sounding board, a bridge secured thereto and a string plate, comprising a tuning pin section and a hitch pin section, and said hitch pin section having a double L construction, whereby strength is imparted thereto and to the string plate as a whole.

7. In a piano, a sounding board, a bridge secured thereto and a string plate above the bridge, said string plate having a tuning pin section and a hitch pin section, and said hitch pin section having a double L shape and being supported by the plate above and out of contact with the sounding board.

In witness whereof, I hereunto subscribe my name this 6 day of April, 1931.

WILLIAM G. BETZ.

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