Patent GB-190513894-A (GB)
Title: Improved Automatic Playing Attachments for Pianos
Filed: 1905-07-05
Granted: 1906-07-05
Abstract: 13,894. Lake, H. H., [Stokes & Smith Co.]. July 5. Automatic instruments; pianofortes. -An electromagnetically - actuated playing - attachment of the shoe and roller type is detachably applied in the upper part of the case of any upright piano. The connexions between the friction shoes and the hammers are such as not to interfere with the use of the keyboard. A conical or stepped roller is employed to graduate the striking force from treble to bass notes and avoid the drowning of the former by the latter. The angle-iron magnet rail 1, Fig. 11, is supported by aogle brackets 2 from the bolster part 3 of the piano frame, and is vertically adjustable by means of slots in the brackets. The reduced ends of the cores of the electro-magnets are inserted in holes in the magnet rail and swaged over. The armatures 15, Fig. 2, are mounted upon blade springs 16, seated in cross-slots in a rail 18 and secured by screws 20. Saddle-pieces 27 are secured between nuts 25 on studs 21 having sockets for the stems of disks 24, which abut against felt-faced nuts 42 supported by studs 40 on a T-bar 33. The armatures are further controlled by coiled springs 36, attached to thumb-screws. A spring lug 39 bears against the milled head of each screw. The lower end of each of the springs 36 passes loosely through a hole in a clip 37 and is bent over as shown, to avoid twisting the springs. The felt-faced rest rail 43 is adjustably mounted by means of slots and screws. The shoes 28 are preferably made of wood, such as maple, in two parts, mortised at 31, and are faced with cork 32 or other material ; they are mounted upon felt-covered pins 29 and are provided with felt-covered pins 49 across channelled portions 50 for the hooked ends of the pull rods 47. The lower end of each of these rods passes through a hole in the twisted end of an arm 59, Fig. 9, which is clamped on part of the hammer action. The threaded part of the rod above the nuts 65 and felt washer 65<1> is covered by a brass or rubber sleeve 64 to permit the arm 59 to work freely over it during manual playing. The arm 59 is preferably formed with a series of holes 60 so that it may be shortened to suit different actions ; it is fixed between the arms 53, Fig. 6, of a sheet metal clamp, which is fixed on the rod p by means of a block 56 with screws 58, which press against a thin steel strip 54 with penetrating points or prongs 57; the ends of the strip are preferably turned over the block to hold the parts together. A modified form of connexion is shown in Fig. 10, in which the hook 68 consists of two metal plates riveted together at 70, threaded for attachment to the threaded end of the rod 66, and clamped by a screw 71 ; the lower end of the rod is provided with a rubber sleeve 74, a felt washer 73, and a head 72, and passes through an open slot 77 in a clip 75, which is secured to the wippen n or other part of the action by means of a screw 79 and a sharp point or edge 78. In another modification, shown in Fig. 16, the pull-rod passes through a felt-lined guide 97, and carries an adjustable felt-faced piece 95, to act on a clip 100 or upon the wippen 7c itself. A flexible connexion may be used as shown in Fig. 14, in which a linen or other tape or cord 101 is secured to the shoe, the edge of which is formed of gradually increasing radius for the purpose of grading the blow. The conical roller is preferably mounted in an inclined position so that the shoes 28 may be of uniform length.