International projectionist (Jan-Dec 1938)

it in securely, but do not use extremely heavy hammer blows. The support must again be used under the central portion of the sprocket. Cut off the projecting portions of the pins flush with the sprocket. The shallow groove at the left end of the intermittent shaft is for the set screws holding the collar. This collar determines the end play. After loosening the screws the sprocket and shaft are pulled firmly away from the machine, the collar is set up close against the bearing, and the set screws tightened. Do not pull too hard, as the sprocket is light and might bend. If the collar has been set up a trifle snug, loosen the set screws slightly, not enough so that they are completely free. Now tap the end of the shaft lightly until it just turns freely; then tighten the screws. Check the adjustment again after tightening the screws. The holes in the ends of the sprocket are to lighten it is much as possible and yet retain the required strength and rigidity. Remember that the sprocket and the shaft are started and stopped 24 times a second, and that the heavier the parts, the harder it is to do this, throwing more strain on the rest of the machine and on these parts, too. Inside the intermittent case is an oil deflector which scoops up oil that is thrown by the star wheel and directs it into the holes to lubricate the bearings. It is a sort of circulating system: oil is constantly draining into the bearings and they are kept practically flooded. • The Motiograph Movement Figure 17 shows the parts of the Motiograph movement. On the left is the cam and its shaft. On the left end is a flat spot against which the flywheel lock screw seats. There is another similar flat directly opposite, for the second lock screw. On the right end of the shaft is the cam ring and the pin. Immediately to the left of the cam ring is a heavy disc, which supports the cam ring and also acts somewhat as a flywheel. Just to the left of this disc is the spiral oil groove. The first impression might be that this is two diagonal grooves or slots, but actually it winds around the shaft and is one continuous groove. Above and to the right is the star and its shaft. This looks very similar to the Simplex star, but close inspection reveals that the back of the slot is closed by a web, which supports the points of the star just where support is needed most. Here we have another oil groove, but this is sort of a double affair. A short groove, hardly discernable in the pic FIGURE 17 ture, tends to send oil from the star end of the bearing into the center. The other groove, which is about twice as long, returns the oil, keeping it from oozing out of the other end of the bearing. The two holes, of course, are for the taper pins. The cam and star operate in a housing containing a semi-solid grease. In action the parts in the chamber churn the grease and, because of the design of the chamber, so keep the grease in motion that it is continually being forced over and around the parts it is to lubricate. The flywheel, as indicated previously, is mounted directly on the cam shaft. To adjust end play, two small screws in the face of the flywheel near the outer edge are first loosened. These screws lock the set screws which fasten the wheel to the shaft. The actual locking screws are two long screws, the heads of which are set in the periphery Simplex E-7 Tips DON'T fill the intermittent movement of the E-7 while the mechanism is in operation. The movement should be filled with Simplex Oil to the indicated level on the sight glasses only while the mechanism is at rest. Provision is made in this movement to eject any surplus lubricant over and above the predetermined amount. When the projector is in operation the oil in the oil well is splashed and pumped all around the internal structure of the movement. Thus any lubricant added at this time will only raise the oil level and be ejected when the mechanism comes to rest, unnecessarily messing up the equipment and causing the projectionist to believe he has an improperly oil sealed movement. Owing to the increased length and larger number of tension shoes on the gate of the E-7 mechanism, a patch passing through the mechanism will make itself heard with slightly more emphasis than on previous models. This should not cause alarm, however, since no damage is done to either the film or equipment. Projectionists will find that it requires only a short time to become accustomed to the slightly different sound in the operation of the mechanism. of the flywheel. After loosening these, the flywheel is pushed inward while pulling out on the knurled retaining screw on the end of the cam shaft, thus removing whatever end play exists. The two long screws are tightened first; then the two small screws. A steel ball is situated at the right end of the intermittent shaft. Beyond this ball is a short plunger which is locked in position by a set screw. To adjust end play in the intermittent shaft, loosen the set screw, push in on the plunger (not too hard), and tighten the set screw. The star wheel shaft turns in an eccentric bushing which is part of a bracket that also carries the outer bearing. While this shaft has two bearings and is adjusted by an eccentric, it is a far different arrangement than was used on projectors years ago. Both bearings are carried in this bracket, and they cannot get out of line. There is only one eccentric, not two as formerly. When adjusting the eccentric the bracket swings in a circle, carrying the bearings with it and maintaining positive alignment. • Star and Cam Relation To adjust for star-and-cam relation, the set screw near the inner bearing is first loosened; then, by means of the two screws which operate against the projection on the bearing bracket, a micrometer adjustment can be obtained by backing off one screw and tightening the other. The position of the bearing bracket can be adjusted exactly as wanted: there is no hit-or-miss procedure as formerly, such as putting a punch into a hole in the eccentric and giving it a haphazard pull. Care must be exercised during the adjustment so that the star is not forced against the cam too tightly. Terrific force can be applied to these parts when turning the adjusting screw. While slowly turning the screw with a screwdriver in one hand, turn the flywheel back and forth with the other hand, but only a small amount, so that the cam ring is always in contact with the curved sides of the star. Tightening of the screw must stop the instant that the slightest drag is felt on the flywheel. Back off the adjustment slightly so that this drag is completely removed. Now see that the bearing bracket is inward as far as it will go, after which tighten the firstmentioned set screw. The real low-down on amplifier circuits in the book SOUND PICTURE CIRCUITS. 208 pages of informative text; illustrations printed separate from text, insuring constant ready reference. Last edition now almost gone. Order direct from I. P. for $1.75, postage prepaid. MAY, 19 3 8 11