(TSO NTERNATIONAL STANDARD 3820 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION -MEXKIyHAPOIHAS OPrAHH3ALIWG IO CTAHIAPTH3ALIWH.ORGANISATION INTERNATIONALE DE NORMALISATION Cinematography -- Sprockets for 8 mm Type S motion-picture film -- Dimensions and design Cinematographie -- Tambours dentes pour film cinematographique 8 mm type S -- Dimensions etconstruction First edition - 1978-02-01 ISO 3820-1978 (E) UDC 778.533.1 : 778.553.1 Ref. No. 1SO 3820-1978 (E) Descrip natography,motion-picture film, motion-picture film 8 mm, pinions, dimensions, specifications. Price based on 8 pages IHS FOREWORD ISo (the International Organization for Standardization) is a worldwide federation of national standards institutes (isO member bodies). The work of developing International Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. Internationa! organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. International ISO 3820 developed by Technical Committee Standard was ISO/TC 36, Cinematography, and was circulated to the member bodies in June 1976. It has been approved by the member bodies of the following countries : for Resale Australia Germany Spain India Sweden Austria Belgium Italy Switzerland Canada Japan Turkey Mexico U.S.A. Czechoslovakia U.S.S.R. Denmark Romania France South Africa, Rep. of Yugoslavia The member body of the following country expressed disapproval of the document on technical grounds : United Kingdom @ International Organization for Standardization, 1978 : Printed inSwitzerland INTERNATIONAL STANDARD ISO 3820-1978 (E) Cinematography - Sprockets for 8 mm Type S motion-picture film - Dimensions and design 1 SCOPE AND FIELD OFAPPLICATION This analysis applies to the feed sprocket, for which the sprocket pitch is generally greater than the perforation This International Standard lays down the dimensions and pitch, and the film must slip in the direction opposite to specifies requirements for the design of sprockets used with the direction of motion. The direction of the friction force 8 mm Type S motion-picture raw stock or processed film. between the film and root surface is such as to assist the feed or the driving action. Of the total 0,046 mm (0.001 8 in) accommodation provided at each tooth for film slippage, 2 REFERENCE approximately 0,013 mm (0.000 5 in) is allocated to the ISO 1700, Cinematography - 8 mm Type S motion-picture combined tolerance of perforation pitch and sprocket tooth raw stock film -Cutting and perforating dimensions. pitch (shorter than average perforation pitch combined with longer than average tooth pitch).An additional 0,008 mm (0.003 in) is allocated for, and corresponds approximately 3 DIMENSIONS AND CHARACTERISTICS to, the distortion resulting from 0,58 N (56,7 gf) of contact loading. The remaining 0,25 mm (0.001 0 in) corresponds to 3.1 The teeth shall be equally spaced at an index angle of O,6 % of film shrinkage. It should be noted that a combina- 360/N degrees, where N is the number of teeth. A suitable tion of 1,16 N (113,4 gf) of load and approximately 0,4 % tolerance for the index angle is ± 1 minute of arc for shrinkage with pitch tolerances is about equivalent. By this sprockets having 12 to 24 teeth and ± 30 seconds of arc for procedure the values of X are determined. As shown in sprockets having 25 to 84 teeth. figure 3, X is the distance measured perpendicular to the radial line intersecting the root of the tooth from a point on 3.2 The root diameter D is computed from the equation : the tooth which is 0,66 mm (0.026 in) above the root circle. D=N 3.4 The minimum values of R2 (see figure 1) have been compute