International projectionist (Oct 1931-Sept 1933)

November 1931 INTERNATIONAL PROJECTIONIST 37 MECHANICAL HINTS Types of Machine Screws A description of the styles of machine screw heads and the method of measuring lengths as indicated by the distances between the arrows: J Round Head Screws have semi-elliptical shaped head. Flat Head Screws have a head with a flat top and a countersunk angle of 82°. Fillister Head Screws have a — r rounded surface for the top L of the head, the remainder being cylindrical. T Oval Countersunk Head or French Head Screws have a rounded surface for the top of the head and a countersunk angle of 82°. Screws Types of Oval Binding Head Screws have a head similar to Stand T ard Round Head Screws with li the exception that the height 1 of the head is less. Flat Top Binding Head Screws have a head with a flat top and straight side. The height of the head is less and the diameter greater than that of Standard Fillister Head Screws. Standard Screw Thread Nomenclature The following terms have been adopted 3 American standard screw thread NUT SCREW nomeclature, and are recognized as such. Major Diameter. The largest diameter of a screw thread. The term "major diameter" replaces the term "outside diameter" as applied to the thread of a nut. Minor Diameter. The smallest diameter of a screw thread. The term "minor diameter" replaces the terms "core diameter" and "root diameter" as applied to the thread of a screw and also the term "inside diameter" as applied to the thread of a nut. Pitch Diameter. On a straight screw thread the diameter of an imaginary cylinder the surface of which would pass through the threads at such points as to make equal the width of the spaces cut by the surface of the cylinder. Pitch. The distance from a point on a screw thread to a corresponding point on the next thread measured parallel to the axis. Practical Hints on Assorted Jobs Varying Speed Motor. A motor in which the speed varies with the load, ordinarily decreasing as the load increases— for example, a series motor, compound motor, or series shunt motor — is called a varying speed motor. An induction motor with a high resistance rotor is also a varrying speed motor. Variable Speed Motor. A variable speed motor is one which can be operated at various speeds, and is usually under control at all times. Railway motors, crane motors and hoist motors are often of this type. Wound rotor induction motors are variable speed motors, and, with proper control equipment, any direct current motor may be a variable speed machine. Reaming Holes. A rat tail file makes a good reamer in an emergency. Put the file into a bit brace and operate the brace backwards. Soldering Ladle. A three-eighths-inch gas cap with a handle on it makes a valuable solder ladle for soldering in close places. Wood Screws. In driving wood screws into hard wood a lubricant makes the job easier. A little machine oil, axle grease, or yellow soap on the thread of the screw saves the strength and patience of the mechanic. Linemen will have the twisting off of lag screw heads by using one of these lubricants. Oil Rings. A substitute for a metal oil ring for bearings can be made by using a piece of stout window cord neatly spliced to the proper size. The cord will soak oil and distribute it to the bearing top efficiently. GoldE S-Alarm A new and highly efficient projection unit of vital importance to a good show 2 Start Motor 1— Get Ready GoldE S-Alarm Says: "I. Get Ready! 2. Start Motor 3. Change-Over!^' YOU can't help but give a smooth, unbroken show with this marvelous timing device. It gives three distinct signals. You can't miss them. You can't mistake them. Good shows help the box office. Plenty of warning relieves you of worry. You don't have to watch the screen at all — a wink or sneeze can't make you miss a cue. Your machine is at full speed — and when you want it there. Not a chance for slow pickup to spoil the show. Installed in five minutes. Adjusted in five more. Never fails ! Nothing to get out of order. Made of steel, bronze, and duralumin finished in black crackle lacquer. Outlasts the projector. Pays for itself in convenience in one performance. Pays for itself at the box office in a month. Write for illustrated folder with full description and moderate price. Another superior GoldE projection achievement GoldE Mfff. Co. g 2013 Le Moyne St., Chicago, HI.