Journal of the Society of Motion Picture and Television Engineers (1950-1954)

The overall dimensions of this splicer are: Height 9 in. Width lUin. Length 17£ in. Weight 17ilb. Maximum power consumption .100 vv The splicer operates on 110/120 v, 50/60 cycles and can be converted for use with 220 v. The castings throughout are #108 aluminum alloy with a hard-baked black crinkle finish. Splicing of Dissimilar Safety Base Materials No trouble has been encountered when splicing present types of film, whether to the same or to dissimilar film. However, different time and heat settings are necessary when splicing dissimilar materials to each other. These settings can be classified as low, medium and high. The Du Pont safetybase film falls into the low category as it has a low heat requirement. Negative Eastman Kodak stock falls within the medium heat requirements, and positive Eastman Kodak stock falls into the high heat requirements. When splicing a low heat requirement material to a high heat requirement material, the higher of the two settings is used. Accuracy of Indexing In the current method of cement splicing, accuracy of the cut with relation to the sprocket hole does not introduce any serious problem. However, where butt-welding is to be achieved, this cut, with relation to the sprocket hole, has to be kept very accurate. To accomplish this, it was necessary to take into account the 0.2% shrinkage tolerated in the motion picture field. Obviously, this eliminated the possibility of using two or more sprocket indexing pins and it became necessary to use only one indexing pin (Fig. 3) for both cuts. Clamping and Parallel Alignment The film is clamped in the conventional way except that a banking edge is required in order to obtain perfect alignment control throughout the splicing cycle. The clamps, therefore, incorpoj-ate a pair of film followers (Fig. 3) which push the film to the banking side of the clamp prior to the clamp's being closed. After the film is indexed and clamped, it is then cut, and the clamp still holding the film is swung through a 180° arc into the heat-sealing position. The same cutting blade is used to cut both pieces of film. As the second clamp is rotated to the heat-sealing position, the edge of the film to be heat-sealed is coated with the plasticizer (Fig. 3). At this point it should be noted that one of the major splicing technique changes is that the film is clamped with the emulsion side facing down and the cellulose side up. Of course, when the film is pivoted over a 180° arc to the heat-sealing position, the emulsion is facing up and the pressure is applied to the emulsion surface. The heat is then applied to the cellulose side (Fig. 2). Acetate Flow During the Heat Cycle 16mm and 35mm film each present different problems during the heat cycle. The frameline of a 1 6mm picture is on line with the sprocket hole, which fills up completely during the heat cycle. With 35mm film, there is also the tendency of the acetate to flow into the four sprocket holes adjacent to the point of weld. To prevent the flow of acetate into these sprocket holes, ears were stamped into the heater platen (Fig. 5). These ears are the same size and shape as the sprocket hole and extend above the stainlesssteel platen by 0.006 in. The acetate, besides flowing sideways, would also flow along the line of heat and out each end if it were not restrained. To prevent this, edge-flow plates (Fig. 5) made of stainless steel are placed against the 184 February 1953 Journal of the SMPTE Vol.60