The handbook of motion picture photography (1927)

PICTURE PHOTOGRAPHY gate, but when it occurs in the midst of a reel it indicates broken film. Stop projector and rethread. Look for piled up film. Film Chatters in Gate — The emulsion from fresh film is inclined to deposit itself upon the film race in the gate. This gummy deposit grips the film and retards motion. In bad cases the film will dance upon the screen and at times it will go into and out of focus. Remove film from gate and scrape the deposit from the film race. Use a horn pallette knife or similar object for this purpose. Never use steel or any material hard enough to scratch the race, as a scratch will act as a chisel to cut more emulsion from the film and so make the trouble worse. Projector Runs Slowly and Irregularly — Unless the current has been cut down too far this means that oil is needed. The projector must be kept properly lubricated, and no bearings allowed to become dry. However, too much oil is as bad as none. If oil is allowed to get upon the film, a spot will result. Take-Up Fails — If the film piles up between lower sprocket and the take-up, something is wrong with the take-up mechanism. If the takeup spindle is stopped, the drive is broken, but if it turns slowly, stopping at the slightest tension, the clutch is not working. Where a slip belt is used, it will often prove that an ex of oil has made the pulley too slippery. A spring belt is seldom subject to this fault, but rubber and leather belts fail in this manner quite often. In the case of portable projectors using a clutch take-up, an excess of oil may be the cause. Remove clutch, cleanse thoroughly in gasoline and replace. 177