US2296698A - Piano string support - Google Patents

Description

Seph- 22, 1942- H. BENloFF PIANO STRING SUPPORT Filed Oct. 9, 1941 2 Sheets-Shea?l l INVENTOR HUGO BENloFF BYMM ATTORNEY Sept. 22, 1942. H. BE'NloFF PIANO STRING SUPORT Filed Oct. 9, 1941 2 Sheets-Sheet 2 Z0 INvENToR Huso BENloFF www ATTORNEY Patented Sept. 22, 1942 PIANO STRING SUPPORT Hugo Benioff, La Canada, Calif., assignor to The Baldwin Company, Cincinnati, Ohio, a corporation of Ohio Application October 9, 1941, Seria-l No. 414,359

7 Claims.

My invention relates to supporting strings in pianos. It is particularly advantageous when employed for terminating the vibratory lengths of the piano strings at their xed ends, i. e., the forward ends of the vibratory parts of the strings in grand pianos and the upper ends in upright pianos.

Heretofore and currently it is a practice in piano construction to provide very rigid supports for the Xed ends or the vibratory parts of the strings, the supports being rigid both in a direction parallel to the string lengths and in a direction transverse to the strings. In a grand piano, for example, the strings in the upper treble register bear upon a stiff rigid member of the cast iron string frame, known as a pressure bar, while in the bass and middle treble registers individual supports for the string or strings of each note have been found desirable. These individual supports, however, known as agraffes, consist of thick metallic eyelet members, rigidly screwed to the string frame and rigidly extending therefrom. Further, in upright pianos the strings at their xed ends bear directly upon substantial ridges of the heavy string frame.

When the strings of a piano are struck by the hammers the vibrations usually considered as occurring in the strings are those of the transverse type, i. e., vibrations in which the string excursions are transverse to the string lengths. piano tones are usually thought of as originating from this form of vibration, through the communication of its motions to the piano soundboard Via the bridges attached thereto.

There is, however, a second type of vibration also produced in the strings when impulsed by the hammers. This latter form of vibration is longitudinal in character, in which the excursions consist of elastic impulses in the direction of the string lengths. It is caused by the fact that the hammers impinging upon the strings drive elastic arcs or bulges into the strings, resulting in vibrations both of transverse and longitudinal nature, and/or by the fact that the motions of the contact surfaces of the hammers at the moment of impact with the strings, are oblique to the string axes thus producing a longitudinal component of string motion.

These longitudinal vibrations are distinctly manifest in the sounds issuing from the piano i' and are of complex vibratory character, containing a fundamental and one or more harmonics. They do not necessarily blend with the fundamental and harmonics of the transverse vibrations of the strings, consequently they detract The considerably from the beauty of the piano tones. The sounds arising from these longitudinal string vibrations are particularly noticeable and objectionable in the bass register of the piano wherein, owing to the strings being loaded with wrapped wire for the usual reasons of securing ilexible bass strings, their frequencies lie in a range in which the sound producing structure of the piano is especially sensitive, and they manifest themselves therein as loud clangs occurring at the onsets of the piano tones.

It is therefore a fundamental object of my invention to minimize the effects of longitudinal string vibrations in pianos, thereby improving the tone of the instruments. Brieiiy, I have found that this can be largely accomplished by providing supports for the fixed ends of the strings, which are resiliently flexible in 'the direction of the string lengths, instead of the relatively rigid supports heretofore and currently employed. With the use of these flexible supports the clang sounds of the piano bass, for example, are greatly reduced, the resulting tones being much clearer and fuller. It will be under- 'P stood, of course, that my invention is not necessarily limited to application in the bass register of a piano but may be employed wherever desirable in any part of the instrument.

I am not completely certain as to the exact causes underlying the improvements effected by the string supports of my invention but I believe the result is attained by a reduction in transfer of longitudinal string vibrations to the piano string frame from the strings at their fixed ends. With the present rigid supports for the strings in pianos this transfer 0f energy is quite effective in respect to the longitudinal vibrations of the strings since the supports rigidly coalesce with the string frame or plate permitting the vibrations to be transferred to the frame and radiated as sound therefrom. This I have noted on removing the soundboard from a grand piano otherwise placing the instrument in an intact condition. Under this experimental condition I have observed that whereas the principal character of the piano tone largely disappears, the clang tones resulting from the longitudinal vibrations remain very forceful. By providing resiliently flexible supports, however, at the iixed ends of the strings, between the strings and the string frame, the clang effect was remarkably reduced. I believe the flexible supports impede the building up of longitudinal vibrations on the string and/or act as a mechanical by-pass (analogous to the electrical ltering action of an electrical condenser), thus isolating the frame from these longitudinal vibrations.

A detailed manner in which I accomplish my invention, including the attainment of the above mentioned object and those other objects which will be indicated hereinafter or will be apparent to those skilled in the art upon reading this speciiication, will now be described, reference being made to the accompanying drawings wherein:

Figures 1, 2, and 3 are respectively front elevational, side elevational, and top views of a piano agraire constructed according to my invention;

Figures 4, 5, and 6 are respectively front elevational, side elevational, and top views of a slightly modied form of agrarie; y

Figure 7 is a partial view'of a piano containing the new agrafes;

Figure 8 is a sectional View taken on lthe section line 8 8 of Figure 7 Figure 9 is a perspective view of modified string supporting means constructed according to the invention;

Figure 10 is a partial view of a piano containing the string supporting means of Figure 9; and

'Figure ll is a sectional view taken on the section line Ic-Ill of Figure 10.

With detailed reference to Figures 1 to 6 inclusive, I have shown 4an agraire comprising an integral metallic member having a threaded end portion I whereby it may be attached to a piano,

threaded holes being appropriately provided in the pia-no plate for this purpose. Intermediate the ends of the agraffe is an enlarged portion or shoulder 'indicated at 2 in'Figures 1, 2, vand 3, or

at S in Figures 4, 5, and 6. As illustrated the shoulder 2 is hexagonal in outline, the agraire having been fabricated from hexagonal metal bar stock, this form of shoulder permitting the ready application of a hexagonal socket wrench to attach the agraire to a piano. The shoulder 3 as shown has two parallel flat portions permitting the use of an open end wrench, the -agrafe having been formed in this instance from round metal bar stock. In attaching the agraies to a piano the threaded end portions are of course screwed into the piano plate -until the shoulders 2 or 3 seat sclidly thereon.

Extending outwardly from the shoulder 2 or 3 in a direction opposite to the threaded portion I is a string supporting portion 4. This portion 4, as shown, comprises a reed-like or plate-like portion, and has a length of about inch and a width of about 7/16 inch. As illustrated two holes 5 have been bored through the portion d in the direction of its thickness, at a position intermediate its ends, i. e., between the shoulder `2, or 3, and the outer end -of the portion. These holes receive the strings for one note of a piano, the agraire being arranged in this instance for that section of a piano wherein there are two strings per note. It will be understood of course that agraiies such as described can also be accommodated for one or three strings per note, the width of V16 inch, slightly less than the intervals of adjacent ygroups of note strings, being suiiicien-t for three holes for receiving a usual triad of piano strings.

As to the thickness of the portion 4 of the agraire, I mal e the agraifes so as to have as little thickness in this portion as practically possible. In this way these string supporting portions 4 become suiiciently iiexible, in the direction of the string lengths and as compared with the heavy metal string frame of the piano, so that `transfer of longitudinal vibrations from the strings to the string frame is eiectively impeded. The agraies however retain sufficient rigidity transverse to the strings to form satisfactory terminations for the strings in respect to their usual transverse vibrations.

Practically, I prefer to make the agraffes of this invention from steel and I prefer to employ a thickness of 1/32 inch for the string supporting portion 4, locating the centers of the string holes 5 about g inch from the shoulders 2 or 3. The portion 4 considered as a beam fixed at one end then has a compliance of about six one hundred thousandths of an inch per pound of force, applied near its holes 5 and bending it in the direction of its thickness. I have found however, that somewhat beneicial results can be obtained with string supporting portions even as thick as @(9,2 inch, corresponding to a compliance of about two millionths of an inch per pound. While these compliance values may seem small it is to be noted that they nevertheless represent considerable flexibility as compared with the rigidity of the string frame to which the agra'ifes are 'attached. Agrales currently used in pianos have a compliance of only about six ten millionths of an inch per pound. Within the spirit of this invention I may of course employ agrafles with string supportingportions less than V32 inch thick, should this be practically possible, and I .may employ brass or other material instead of steel for the structures.

Figures 7 and 8 show the agraifes mounted in a grand piano, the -gures illustrating a forward part of the piano string frame or plate, and related parts. As shown the agrafes are tightly screwed into the plate 'I, the piano `strings '6 passing through the holes 5 to be supported by the portions t which extend in width and length transverse to the strings. Also attached to the plate 'I is a usual tuning pin block 9 holding the tuning pins 'lil for tuning the strings 6. I-Iammers I2 for striking the strings are indicated at I2.

Figure 9 shows a modified form of stringssupporting structure for sustaining the strings of a plurality of notes in a piano. This structure comprises an elongated metal member I3 having a series of turned up reeds-like projections I4 along its length at intervals corresponding to the strings of a series of notes. The projections -I4 have lengths and widths corresponding to the above described agrailes and the structure `is formed from 12- inch metal sheet, preferably steel, to provide a desired thickness for the projecticns. Thus a desired flexibility for -the projections IIS as string supports is obtained. Placed i-n the body :portion of the structure are la number of holes I5 for attaching it to the string frame -of a piano while the respect-ive shoulders or slots I6 -in the projections Iii receive the Vpiano strings.

In Figures -10 and l1 members such as I3 =are shown attached to an upright piano, being-held to the piano string frame or plate II by `the heads of machine screws I3 passing through the holes I5 and screwed into the plate I1. As Villustrated the piano strings I9 bear upon the `projections Ili in the shoulders or slots Iii. Other piano parts shown comprise hammers -20 for striking the strings, and apin block 2I attached to the plate II and containing tuning pins 22 engaged by the strings I9.

Being thus described those features of my Yin vention which I `considernew and novel, and Vdesire to protect by Letters Patent comprise:

1. A piano string support comprising a member having an intermediate shoulder, a portion extending outwardly from said shoulder and adapted for attaching said member to a piano, and a string supporting portion extending outwardly from said shoulder opposite to said rst mentioned portion, said string supporting portion comprising a plate-like portion having a width of the order of the intervals of strings of adjacent notes in a piano, adapted to receive a piano string at a position spaced from said shoulder and having a compliance, at said position and the direction of the string length, greater than two millionths of an inch per pound, whereby said string supporting portion under the vibrations of a supported string yields resiliently parallel to the string length.

2. A piano agrarie comprising a metallic member having an intermediate shoulder, a threaded cylindrical portion extending outwardly from said shoulder whereby said member is attached to a piano, and a string supporting portion extending outwardly rom said shoulder opposite to said threaded portion, said string supporting portion comprising a plate-like portion having a width of the order of the intervals of strings of adjacent notes in a piano, adapted to receive a piano string at a position spaced from said shoulder and having a thickness less than seven sixty fourths of an inch, whereby said string supporting portion under the vibrations of a supported string yields resiliently parallel to the string length.

3. An agrarie as set forth in claim 2, wherein said shoulder is polygonal in shape whereby said agraffe may be readily attached to a piano.

4. Means for terminating the active lengths of strings in a piano, comprising an elongated member adapted to be rigidly attached to a piano frame, said member having a series of transverse reed-like projections at intervals corresponding to the strings of a series of notes in a piano,

arranged to outstand from the piano frame when said member is attached thereto and to support strings at positions spaced outwardly from the piano frame, said projections having each a compliance, at said positions and in the directions of the string lengths, greater than two millionths of an inch per pound, whereby said projections under the vibrations of supported strings yield resiliently parallel to the string lengths.

5. An agrarie for terminating the active length of a string in a piano, said agraie comprising an attachment portion by which it may be engaged with the plate of a piano, and a portion extending outwardly from said first mentioned portion and from the plate with which it may be engaged, said outwardly extending portion having means for engaging said string at a point spaced from said attachment portion, and having at said point with reference to said attachment portion a compliance which is greater than two millionths of an inch per pound.

6. The structure claimed in claim 5 in which the said outwardly extending portion has a thickness less than seven sixty-fourths of an inch.

'7. A piano agrarie comprising a metallic member having an intermediate shoulder, a threaded cylindrical portion extending outwardly from said shoulder whereby said member is attached to a piano, and a string supporting portion extending outwardly from said shoulder oppositely to said threaded portion, said string supporting portion comprising a plate-like portion having width of the order of the intervals of strings of adjacent notes in a piano, adapted to receive a piano string at a position spaced from said shoulder, and having a compliance at said portion and with reference to said threaded portion, which is greater than two millionths of an inch per pound.

HUGO BEN'IOFF.

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