International projectionist (Jan-Dec 1955)

wear of the intermittent-sprocket teeth; and hooked teeth, in turn, chip and tear the pull-down edges of the perforations. It is essential that the tension be the same at both sides of the gate. The pads which hold the film at the aperture should have somewhat greater pressure than the higher set of pads. Adjusting the Guide Roller Incorrect lateral adjustment of the flanged guide roller at the top of the gate may indirectly damage the film perforations. The purpose of this roller is to edge-guide the film as it passes down into the gate. A change in the position of the guide roller produces a corresponding lateral shift of the film in the gate and on the face of the intermittent sprocket. The sprocket teeth, however, limit the amount of lateral shift possible on the sprocket. If the guide roller is shifted too far to one side therefore, the sides of the perforations bring up against the ends of the sprocket teeth, and the film assumes a slightly slantwise course in the film gate. The result is that the sprocket teeth engage the perforations on only one side of the film. Excessive wear of the perforations on this side of the film ensues, and if this undesirable condition is not corrected, the teeth on one flange of the sprocket wear more than those on the other flange. The flanged guide roller must revolve freely. If the film fails to turn it, the shaft and pivots may be clogged with dirt, the pivots may be too tight, or the tension of the coil spring too great. The tension of this spring is critical. Guide Roller Flanges If the movable (inner) flange presses against the edge of the film too strongly, the film will tend to crimp as it enters the gate, with resulting sidewise unsteadiness of the projected picture. Only very little tension is needed for proper film-guiding. A spring that pushes the flange against the film too tightly may be weakened by cutting off and discarding a few turns from the coil. The flanges of guide rollers which NAIL YOUR PICTURE TO THE WALL! You can, of course, simply by having your projectors overhauled using LaVezzi replacement parts. You will find the projectors give a steadier picture, operate more quietly, need less service, and the parts will last longer — See your Theatre Equipment Dealer 7^^/^^ about this important improvement in your theatre. ^fSX.V^r LaVezzi Machine Works 4635 WEST LAKE ST. CHICAGO 44, ILL. fail to revolve become grooved by the film. Grooved flanges roughen the edges of the film and tend to tear the corners of splices. Weak splices may come apart when they encounter a defective guide roller. Valuable footage may be destroyed if a film break occurs anywhere in the projector or soundhead. Film may wind up on a sprocket or pile up in the machine. Breaks in the older types of soundhead often result in "pleating," a folding up of the film in the manner of an accordion bellows. All multilated footage should be removed from the machine and thrown away. If a great deal of film has been lost, the exchange would appreciate being advised of the reel number and footage numbers printed in the perforation margin of the damaged film. It is also a good idea to explain the circumstances of the film break. Film breaks, we repeat, are avoided by adequate film inspection and painstaking projector maintenance. Reel-End Alarm Riders Last but not least the projectionist must consider his reel-end alarm riders as possible causes of scratched film. This type of signalling device usually employs a small roller which rides on the emulsion side of the reel of film in the upper magazine. If the roller does not turn freely, or if it has become burred or damaged, it may inflict a series of lengthwise scratches on the picture area of the film. It is only fair to state, however, that an examination of the reel-end alarm devices in a large number of theatres indicates that they seldom cause any injury to prints. [END OF SERIES] I UNION MADE FISHER MANUFACTURING CO. nss mt. read blvd., Rochester «, n. t. _ EOT UNION MADE | ! INTERNATIONAL PROJECTIONIST • AUGUST 1955 33