Exhibitors Herald (1925)

March 28, 1925 EXHIBITORS HERALD 17 Fig. 4. Sprockets taken from projectors actually in daily use. Sprocket A is a new sprocket. Fig. 11. Here the film gnide is upside down allowing the film to strike the sharp end of the guide. Stiff splices won*t last under these conditions. Fig. 5. This guide roller is not adjustable. Spring 2 is supposed to hold it snugly against the washer 1. If it is not properly aligned, return the head to the manufacturer. Fig. 8. The teeth of this sprocket have been undercut because the takeup was too tight. Fig. 12. Shows 1 the feed sprocket and the small roller 2. alteration necessary. The larger idler makes the film last longer. Fig. 6. This guide roller may be adjusted by loosening the set screw in collar 2 and then after centering tightening the screw. Great care should be taken not to “spring'* the shaft. Fig. 9. The arrow shows where the teeth have been grooved to a knife-like sharpness by coming in contact with the wall of the film guide. This will ruin the film. Fig. 14. Suddenly jerking the framing lever on this machine puts a kink in the film shown by the arrow. Frame carefully and slowly. Fig, 7. The arrow shows where the film edge has been chewed away by bent reels or imperfect alignment of the upper magazine. Fig. 10. This is the correct position for the film guide. Arrow 1 shows the guide holder and 2 is the film guide. Fig. 15. On this type of projector, also in common use, buckling of the film will occur if framing is done too rapidly. Eastman Kodak Company, Rochester, N. Y. Whenever film is damaged on a projector, it is generally customary to lay the cause of the trouble to one or more of three different things; namely, sprockets, idlers, and tension exerted on the film by the springs in the gate or film trap. While it is true that in most cases the trouble can be traced to one or more of these points, it must be admitted that the direct cause of a great amount of film damage is never definitely settled between the film exchanges and the projectionists, especially when the projectors in question have been gone over quite carefully and everything has been found to be in apparently good condition. In cases of this kind, it is only natural to assume that the film stock is at fault. There are, however, various projector parts, generally considered more or less unimportant which, as a rule receive little or no attention on the part of the projectionist. The result is that film trouble is apt to start at any one of them. The following resume covers the more important points which must be given careful attention by the projectionists, if the maximum wearing qualities are to be obtained from the film. Tension on Springs in Gate or Trap One of the principal sources of trouble is the use of excessive tension exerted on the film by the springs in the gate or trap. A great variation will be found in tension on various projection machines being used in the trade. Moreover, there are some projectionists who are not familiar with the amount of tension which should be used, and as far as we know, there is no set standard which is generally accepted as being correct. It is common practice to set the springs just tight enough to hold the film stationary at the speed which is used in a given theatre. For proper screen reproduction the speed of a projector should be determined by the action of the picture. This is very seldom done, the average program being run at one set speed regardless of the action. This cannot be considered the fault of the projectionist as he is under a certain time limit to project a given number of reels. Excessive tension as high as 34 ounces has been found to exist on certain projection machines and causes badly nicked and pulled out perforations. Heavy tension on one side can be caused by a poorly adjusted, weak or broken spring and results in an uneven pull-down strain on the film. On projectors using the gate a stop or catch is provided which holds the gate in the same position each time it is closed. Projectors using a trap door or pressure plate are not provided with a stop of any kind, thereby allowing varying amounts of tension to be applied to the film. The trap door or plate should never be let back against the film with great force as this results in exceptionally heavy tension, which must be withstood by the film until the door or plate has worked back to its proper position. The proper tension exerted by the springs should be 8 ounces for each spring or 16 ounces combined tension. {Continued on page 34)