Moving Picture World (July-Dec 1909)

THE MOVING PICTURE WORLD 883 Progress in Machine Construction. THE POWER'S CAMERAGRAPH NO. 6. We have heard so many operators speak highly of the practical value and efficiency of the Power's Cameragraph that we here present a full description of the Power's Company's latest introduction, the No. 6, which has just been placed on the market. Every part of the mechanism is made of the best material and is of ample size and strength to withstand the strain of constant service for many hours every day in the year. The frame is heavy and rigid; the gears are of large diameter and wide face, with spirally cut teeth which reduce noise, eliminate "back-lash" and insure steadiness of operation. The larger gears are made from a special alloy which reduces friction to a minimum, and the pinions are cut from the best grade of machine steel to withstand wear. The bearings are of exceptional length, insuring perfect alignment of the shafts or spindles which are of extra large diameter to prevent bending. All parts are interchangeable and are gaged with the highest degree of accuracy. The most striking feature of the No. 6 Power's Cameragraph is perhaps the intermittent movement, or driving mechanism for the intermittent sprocket. It is a departure from the various intermittent movements which have been used on moving picture machines in the past. Heretofore, those machines which have been equipped with intermittently rotating sprockets have been almost universally supplied with the well-known Geneva movement, which comprises a star wheel with four slots and a cam or pin wheel by which the star wheel is turned through the engagement of its pin with the slots of the star wheel. By this arrangement, the intermittent sprocket is given a turn through ninety degrees at each rotation of the cam or pin wheel. The wear upon the pin and the star wheel is rapid, and frequent replacement is unavoidable. As compared with the Geneva movement, the new intermittent movement of the No. 6 Power's Cameragraph presents two marked advantages: the period required for a quarter turn of the sprocket is materially shortened and the parts comprised in the intermittent movement are of durable construction. The light and fragile pine wheel and star wheel are done away with. Instead of the former, a cam of specially hardened tool steel is substituted and in place of the latter, a heavy steel cross with a pin or stud on each arm is supplied. These pins are engaged by the cam at each rotation of the main driving shaft, and the wear is distributed Figure 1. over all four pins. The construction of both the cam and the cross is shown in Fig. 1, and it will be seen that the operation of the movement is free from strain or wear upon the moving parts. The revolving shutter is enclosed within the frame of the machine where it is protected from injury, and where it cannot interfere with the use of lenses of the longest focus, and it is mounted in front of the aperture plate or picture gage, so permitting the use of a lens of the shortest possible focus. The shutter gears are angle gears (not bevel gears) and are over an inch in diameter with faces three-eighths of an inch wide. The picture is framed by a slight vertical movement of a carriage bearing the intermittent sprocket, and the framing lever is mounted on the base of the mechanism or machine head, where it can be readily reached with the left hand without interfering with the operation of the machine. The movement of the framing carriage does not alter the relation of the shutter to the picture gage or projection aperture. The gearing connection to the framing carriage has all the gears arranged in a straight line, eliminating the toggle joint and toggle joint gears. The film feed comprises three sprockets; the top feed sprocket, the middle or intermittent sprocket and the bottom or take-up feed sprocket The film is held in position upon the top feed sprocket by means of two flanged rollers turning on fixed spindles which insure perfect enngagement of the film perforations and the sprocket teeth, with the least possible wear on the film. A hardened steel shoe with flanged sides holds the film in contact with the middle or intermittent sprocket over more than one-fourth of its circumference. This shoe is so set that it exerts no pressure on the film, and a steel roller is provided to prevent frictional contact of the film with the shoe as it leaves the intermittent sprocket. The bottom or take-up feed sprocket controls the rate at which the film is taken up in the lower mechanism, and a steel shoe with flanged sides holds the film on this sprocket without pressure against the film. The tension on the film necessary to insure steady pictures is produced by means of the aperture plate, which is provided with wear strips of glass-hard steel, and a pair of tension springs provided with half-round hardened steel contact shoes on which soft emulsion or film cement cannot accumulate and scratch the film. The film is held flat with less friction than is produced by any other type of film "tension device. The safety devices, to protect the film from fire, comprise upper and lower magazines, an automatic fire shutter and upper and lower film shields. The fireproof film magazines are of the square type, insuring easy insertion and removal of the film and reels, and are provided with valves that prevent the passage of flame into the magazines. The lower magazine is provided with Power's patent automatic take-up device which maintains a uniform tension on the film at all times, whether the reel be empty or full. The automatic fire shutter is simple in construction, and the operating mechanism readily accessible. The parts are constructed to withstand wear and bperate with very little friction. A little heavy oil or melted vaseline should be used to lubricate the parts from time to time to insure perfect operation. The film shields protect the film in its travel from the upper to the lower magazine. The upper film shield is mounted on the film gate and moves out of the way when the gate is open for threading the film through the machine. The lower film shield is mounted on the base of the machine