Movietone Bulletin (September 1928)

Oiling and Over-Oiling O ONE thing works greater harm to film or greater injury to what audiences see upon the motion picture theatre screen than does over-oiling motion picture projector bearings. This same thing also is or may be responsible for much damage to movietone sound reproduction. Certainly no true movietone projectionist would be guilty of so gross and totally unnecessary an abuse, but unfortunately they cannot control oiling in projection rooms other than their own. Over-oiling is usually due “either to just plain carelessness or to lack of knowledge on the part of the projectionist committing the fault. I almost said committing the outrage. Had I done so would any say that I was over harsh? However, whether it be carelessness or lack of knowledge, the results are the same. The film receives a more or less thorough spattering of oil and each spot gradually spreads until a large portion of the film surface is covered. You all know the result, both to the picture and to sound. Over-oiling is entirely unnecessary, in that it does no good in any degree commensurate with the damage set up. In fact it may well be questioned whether or no overoiling does any appreciable good at all. Certainly it does plenty of harm. What’s that? What constitutes just the correct amount of oil for a motion pitcure bearing, do you ask? A fair question. Unless I can answer, the energy used in writing this article up to this point has been wasted. First let us examine into just what constitutes lubrication. What office does lubrication fill? As you all know, dry metals, rv. + bing one against the other under pressure, wear. Friction is set up and tiny particles are torn from both surfaces. This same thing is true, in lesser degree, with wet metal surfaces. The problem then is to separate the surface of a spindle or shaft from the bearing in which it runs by means of a substance over which metals will slip with little if any friction, and that is exactly what the oil you pour into a bearing does. We are told by scientists that, incredible as it may seem to you and me, oil which has proper “‘body” actually does, separate a shaft and bearing so that the metal of one does not touch the metal of the other at all. What we then do in oiling a bearing is supply just sufficient oil to form such a film, which in practice means using a new bearing and shaft sufficient to fill the slight space between shaft and bearing. Of course if we put any more oil in than this space will contain it will, perforce, run out. That is just plain common sense, is it not? All right! Now consider a new projector. Do you for one moment imagine that there is more than sufficient space between any shaft and bearing thereon to hold in excess of two drops of oil? Think that over, brother! If you decide that there is not, then it follows that if you put more in the oil hole, the surplus over two drops will just run through the bearing and out. And what will happen to it when it runs out? Very likely it will be thrown off the moving parts by centrifugal force, is it not? Pretty likely also that the film will be the goat, what? We thus arrive at the conclusion that two drops is quite sufficient for any motion picture projector bearing that is not worn. But if it is worn, does that alter the requirement? It does not, because of the fact that there is still quite sufficient oil in two drops to form the protective film on the shaft and bearing, and that is all that is required. I think we may safely set up the following rules with relation to projector oiling: (a) Use only the oil recommended by the projector manufacturer. (b) Give the smaller bearings carrying relatively slow speed shafts one drop of oil every two hours of actual running. Give the heavier bearings and the high speed bearings two drops of oil every two hours of actual running. (c) Under no circumstances use light oils such as 3-In-One for motion picture projector bearings. Such oils doubtless have their proper uses, but projector lubrication is not among them. ‘They have not sufficient body to lubricate projector bearings adequately and they are so thin that they will be readily thrown off moving parts. Of course I know one and two drops every two hours of operation will seem terribly small to you chaps who have been accustomed to giving each bearing a literal bath of oil every once in a while, but I assure you the quantity I have suggested is ample and the time between oilings is quite all right. Your projectors will last just as long as they did before and the films—well, if they had voice, they certainly would arise and call you thrice blessed. Watch the Intermittent Movietone projectionists will do well to watch their projector intermittents closely. Remember that there is a very exact relation between the projector aperture and the sound gate registration. If your intermittents have considerable lost motion—circumferential movement in the sprocket—the result will be the lack of exact synchronization as between the two registrations. Of course, unless it be very bad indeed, this probably won’t amount to very much, in so far as has to do with the screen effect, but just the same, it won’t be 100 per cent. perfect, and that’s what the true movietone projectionist seeks. Watch your intermittents therefore, and keep them in the most perfect possible adjustment. Every little fault eliminated helps toward perfection. Is it not so? (Continued from Page 1, Col. 2) the sound volume necessity no fixed rule can be established. The shape of the auditorium, its cubical content and its seating capacity, all are factors which must be considered in determining the required set size. Broadly the 46 type amplifier is for a small auditorium, the 42 or 9 A for a medium size and the 48 or 10A for a large size. As I have said, however, all that depends in very large measure upon the local conditions. Actions speak louder than words, they say. But not since movietone was invented. One kind of prosperity that never makes a fool out of anybody is somebody else’s. Don’t make progress like a crawfish. His future is always behind him.