International projectionist (Jan 1963-June 1965)

FIG. 6 — The motor-driven friction-clutch unit of the Bauer U2 features a load-dependent friction takeup whose degree of coupling is determined by the weight of the reel itself. This device assures a constant, even pull on the film. unevenly, if the sprocket holes of the film are torn when the projector 3tarts up, or if the lower reel fails to start turning when fulh loaded las when the projector is switched on again after a shutdown near the finish of a reel I . 1. Remove the takeup belt. 2. Remove the loeknuts. tension spring, pulles ami flange, and friction-disc assembh from the reelspindle shaft, and pull the shaft from the lower magazine after loosening the retaining collar. ). Clean all metal parts of the completeU dismantled takeup unit, using Carbona (a carbon tet and gasoline-naptha mixture) or lighter fluid (verj inflammable! i to remove grirm grease and deposits of dirt. Examine the slip-friction surfaces of both metal clutch discs or flanges to make sure that these surfaces are smooth, i If they are scored or scratched, they must be replaced with new components. I 1. If the leather or cork friction discs are worn or damaged in any way, replace them. Otherwise wash the leather disc in Carbona or lighter fluid to remove the oil it may have soaked up. Allow to dry. then rub one side only of the leather disc with a very small amount of Vaseline. But note that Motiograph cork friction discs are treated differently: they should be soaked in projector oil. 5. Oil the reel-spindle shaft and reassemble the takeup. Do not oil the slipping surfaces of the metal flan ice-discs! Be careful not to spill projector oil upon the friction clutch when routinely lubricating the gear side of the projector and soundhead! 6. Examine the takeup belt carefully. If rotten, grease-soaked, or frayed in the vicinity of the coupling staple, replace it with new leather belting of the best quality obtainable. Never use belts made up of several leftover ends of belting — no more than one staple should be present in a belt! 7. With a sharp awl. punch the holes to receive the the coupling staple. Try the belt on the machine to see if it is really tight. If not tight enough, remove the staple, cut off a small section from one end of the belting, and punch a new hole for the staple. The takeup belt, we repeat, must be very tight, and the tautness checked from time to time. o. Loosen the set-screw of the locknut on the end ol the spindle shaft and adjust the tension spring so that a full reel of film of the largest size used in the projector starts turning the moment the projector motor is -witched on. But test the revolving reel of film by holding it back from turning with the finger in order to guard against excessive tension which could easily tear the sprocket holes of the film. Not too much force should be necessary to restrain the reel while the projector is running. Adjustment ol the friction-clutch tension spring is essentially the same for the Simplex. Wenzel. ERPI universal base. Motiograph. Philips, and many other popular makes of projector. When the tension spring i correctly adjusted, the film winds up uniformly. \et with just sufficient "looseness" of the roll to be detected when the roll is pressed in from opposite sides with the fingers. 9. \\ hen the takeup tension is at last just right. tighten the set-screw of the split locknut securely. Many projectionists use two loeknuts on the spindle shaft for extra safety. At any rate, it is a good idea to have a lew extra loeknuts in the spare parts cabinet. Holdback Sprocket Important \ "singing holdback sprocket is commonly attributed to excessive takeup tension which pulls the film too taut between the sprocket and the reel. This is true: but worn holdback sprocket teeth will also cause a loud buzzing noise and chip or tear the film perforations. It has been the writer's experience that some "singing of the holdback sprocket of the venerable old KRPI universal base is normal even when takeup tension is correct and the sprocket teeth are in good condition. This sprocket, by the way, is located in the lower-magazine compartment, not in the soundhead when the old-style gate-type Western Electric soundhead is used on the universal base. W hen checking the condition of the teeth of the holdback sprocket, remember that it is their upper edges which become hooked or undercut — this sprocket does not pull the film down, but literally holds it back and takes all the strain imposed by the tension of the takeup friction clutch. It restrains the speed at which the lower reel turns. The bad effect on the film of excessive takeup tension or worn holdback-sprocket teeth can be seen by examining the perforations anywhere in the first 25 feet or so of a reel which has been run through the projector. Holding the film so that the tiny pictures appear right-side-up. and using a magnifying glass, note the position of any^ cracks or tears present in the edges and corners of the sprocket holes. Cracks at the tops of the perforations (pulldown edge) are usually caused by worn intermittent-sprocket teeth and /or excessive gate tension. Cracks at the bottoms of the perforations (holdback edge) are caused by worn holdback-sprocket teeth and /or excessive takeup tension. International Projectionist November. 1963