International photographer (Feb-Dec 1929)

Thirty-four The INTERNATIONAL PHOTOGRAPHER November, 1929 Qflexible Thrive Shafts Their Application to Sound Pictures BY J. C. SMACK, Industrial Division , The S. S. White Dental Mfg. Co. Before describing the actual applications of flexible drive shafts to motion picture equipment, it might be well to give you as briefly as possible a general description of flexible shafts and their characteristics. Flexible shafts are manufactured in all sizes from .041 inches to .750 inches in diameter and larger. The material itself is a special grade of steel music wire of high tensile strength and may be wound in any number of layers from two to nine, according to the type and size of flexible shaft desired. Shafts of widely varying characteristics may be produced by different combinations of wires, by differences in number of layers and subsequent heat treatment. Irrespective of diameter, flexible shafts are regularly made in two general types, classified as Grade "H" and Grade "S." The Grade "H" flexible shaft has high torsional strength, or resistance to twisting strain, and is adapable to the majority of uses. Grade "S" shafting has greater flexibility than Grade "H" and is usually used where extreme flexibility is the deciding factor. Various other grades are also supplied for special applications. To be more specific, let us investigate the characteristics of those shafts most widely used in the motion picture industry, that is, the %" and 5/16" diameters. A flexible shaft, to be satisfactory for synchronized sound-motion picture equipment, must be flexible transversely — must be as torsionally stiff as practical, and still not be too heavy or cumbersome for general use. To this end the %" diameter Grade "H" Left Lay Shaft was selected for driving the Bell & HowellWestern Electric Cameras. This shaft has sufficient flexibility to allow the motor to be placed under the camera, to one side, or whatever position is the most convenient for the operator. The safe allowable torque on this shaft at 1450 r.p.m, the speed of the camera drive shaft, is 13 inch pounds, considerably more than the actual torque of the camera at any time. Extensive experimentation with this shaft indicted its altogether satisfactory performance and it was adapted by the Western Electric Co. as standard equipment for their cameras. In the selection of a casing for this application, the y2" diameter fabric type was used, due to its lightness in weight and flexibility. Further experimentation on various types of camera drives indicated that there were cameras which exerted a greater torque on the flexible shaft than others. Investigation showed that some cameras, in particular the new sound cameras, were considerably stiffer in operation than others. Some were so stiff that at times a wobble or fluctuation was experienced in the camera drive. A larger shaft, the 5/16" diameter, was substituted for the *4" and no further trouble was experienced on these cameras. With this shaft a $/%" diameter two-wire Black Japanned Metallic Casing is used, or a 5/n" diameter Rubber Covered Casing. For cameras used without a soundproof booth, the Rubber Covered Casing is the best as it will deaden any slight noise caused by the rotation of the flexible shaft. Somewhat the same effect can be obtained with the metallic casing, by covering it with a light flexible rubber tubing. It is also advisable to grease the flexible shaft occasionally with a good grade of light grease. Attachment of the flexible shaft assembly to the motor is usually made with a special ball bearing motor coupling manufactured for this purpose and designed to fit the standard end fittings furnished on stock J4", Y%" and Y%" diameter flexible shaft combinations and their respective casings. These couplings are also supplied in various sizes to fit standard size motor shafts. Due to the many types of cameras, there is no standard adapter made for attaching the flexible shaft drive to the camera. It is, however, a simple matter to have one made to fit both the camera drive shaft and the standard end fittings provided on the flexible shaft and casing. Flexible shaft camera drives are usually used in lengths from 3 ft. to 6 ft. and in special cases up to 10 ft., the length being governed of course by the position of the motor. So much for camera drives. AN IMPORTANT EVENT Charles F. Eichhorn, vice-president of Local 306, of the I. A. T. S. E. & M. P. M. O., will address the Trade and Public Press of the United States, at a luncheon to be held by the Projection Advisory Council, at the Hotel Astor, New York, Thursday afternoon, November 14th. It is believed that it is the first attempt of this nature to secure recognition of the responsibilities of the projectionist and the importance of projection. For many years projectionists and others interested in projection have realized that there was urgent need that the Press should be better informed regarding the technical side of the motion picture industry. After Mr. Canavan's talk, an open forum will be held and the Press invited to ask questions which will be answered by certain men selected for this purpose. It is to be hoped that a better understanding will be created through friendly contact and the Press have a more sympathetic and better informed viewpoint regarding the technical and practical problems of the motion picture projectionist. Mr. Eichhorn is chairman of the Projection Advisory Council Luncheon Committee, and all those desiring tickets for this event are requested to communicate with him. TECHNICOLORINGS The latest M-G-M all-color all-sound production, "The Rogue Song," has just reached completion at the Culver City plant. Technicolor cameramen who are responsible for the photography are as follows: Percy Hillburn, Charles Schoenbaum, Friend Baker, Earl Stafford, John Landrigan, John McBurnie, Chas. Riley and H. C. Ramsey. * * * After a five-week schedule at the Warner studios "Hold Everything," an allcolor all-sound feature has finally reached the laboratory. The Technicolor staff lines up as follows: Frank Good, Lee Davis, Milton Bridenbecker, Earle Walker, Harry Hallenberger, Chas. Geisler, Eddie Garvin and Carl Guthrie. * * * Color sequences for Henry Sharp's new talkie feature for M-G-M, "Lord Byron on Broadway," were made by Howard Greene, Allan Davey, Ira Hoke, Chas. Bohny, Maurice Kains, Chas. Straumer and Robert Tobey. * * # John S. Landrigan, formerly of the Paramount studios, has joined the Technicolor camera staff. * * * Harry Hallenberger, Paramount cameraman for many years, has left his old home for the Technicolor lot. Harry has just finished work on the Warner feature, "Hold Everything." * * # Eddie Garvin has joined the line up of crack assistant cameramen at Technicolor. COCRZ LENSES/ The cinematographer who does not use them, does so only because he is unacquainted with the experience of using them, unaware of those qualites of super-fineness which have made them famous throughout the world in every branch of photographic art. The Hypar Series, from f 2.7 to f 3, from 15 mm. (sub-standard) to 4-inch focal lengths are recommended everywhere by the wisest heads in cinematography. GOERZ ACCESSORIES They are standard to the professional photographer, the amateur photographer, the professional cinematographer. the amateur cinematographer, the photoengraver, the scientist, the projectionist, and in the many specialized fields that utilize optical equipment. SPECIAL DEVICES The firm of Goerz is the first thought of the worker whose requirements deviate from the ordinary. We place OUT factory, skill, knowledge, research, experimental staff, and years of experience at the disposal of every indvidual or firm who calls upon us. Write for specific information or literature in general. C. P. Goerz American Optical Co. .: I!)-B East 34th St. New York City