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Gage Design and Gage-Making Manual

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Gage Design and Gage-Making

A treatise on the development of gaging systems for interchangeable manufacturing, the design of different types of gages and their production, including precision machining operations, lapping, and various modern appliances for gage measurement.

By: Erik Oberg and Franklin D. Jones, First Edition 1920

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Chapters I - III Gage Design and Gage-Making

Chapters IV - VII Gage Design and Gage-Making

Chapters VII - Index Gage Design and Gage-Making

The cost of manufacturing any mechanism may be greatly affected, first, by the tolerances specified, and, second, by the gages used to insure that these tolerances are adhered to. There has been, and still is, a great deal of misunderstanding with regard to tolerances and their application in shop work. Briefly stated, tolerances should be based upon the working requirements of the mechanism to be made, and should be as large as possible, consistent with the purpose of the part or combination of parts to be made. Unnecessary accuracy which does not improve the product merely increases the manufacturing cost, and, hence, is sheer waste. After the tolerances have been established, the means for insuring that the desired tolerances are adhered to in the machining operations must be considered. The gages to be used must be so designed and made that they are not only accurate, but practicable, and adapted to shop use. The relation between the gaging system and the design of jigs and fixtures is also essential.

This book deals with such fundamental and vital points as have been outlined above, and is, therefore, regarded as a valuable addition to the technical literature of the day. Much has been published on manufacturing practice, but comparatively little on the design and making of gages; yet, gages control the different manufacturing processes and insure that the required degree of interchangeability is obtained.

As the design of any one gage or group of gages is dependent upon such factors as the location of the finished surfaces, the shape of the part, its size, the degree of accuracy required, etc., it is, of course, necessary to adapt each gage to its particular purpose; but while these factors may be combined in an endless variety of ways, and gages, therefore, differ greatly in form, size, and arrangement of detail, they all conform to certain principles which experience and practice have proved to be correct. This book deals in part with these basic or fundamental principles, and includes information on the making of gages and on methods of measuring and testing them to insure conformity to given dimensions.

That part of the book dealing with the development of gaging systems and gage design is based largely upon the experience and practice of the Pratt & Whitney Co., in making gaging equipment for small arms and heavy ordnance. The manufacture of munitions of war has emphasized the great importance of adequate gaging systems in a more forceful manner than the production of tools and machines used in peaceful pursuits, and the Pratt & Whitney Co., has probably done a greater pioneer work along these lines during the past few years than any other concern. In the preparation of this part of the material, the authors have been substantially aided by A. E. Larsson, engineer of the Equipment Division of the Pratt & Whitney Co. Valuable material has also been obtained from articles in MACHINERY contributed by a number of other men experienced in gage-making.

CHAPTER I
DEVELOPING A GAGING SYSTEM
Interchangeability and Its Relation to Manufacturing - Definitions of Terms used in Gaging Inspection, Working, and Reference Gages - Gage Tolerances Marking Gages - Relation of Gaging System to Kind of Work Procedure in Developing a Gaging System Tolerances for Different Machining Operations 1-48

CHAPTER II
SNAP AND PLUG GAGES
Solid and Built-up Snap Gages Reference Gages for Snap Gages Modifications in Making Snap Gages Plug Gages - A Practical Ring, Plug, and Snap Gage System Plug and Ring Gage Allowances Windmill or Wing Gages 49-78

CHAPTER III
CONTOUR OR PROFILE GAGES
Guided Contour Gages Matching Type of Contour Gages - Receiving Gages Dial Indicator Contour Gages and Their Advantages Indicating Tolerances for a Contour - Different Designs of Dial Indicator Contour Gages 79-101

CHAPTER IV
FLUSH-PIN, SLIDING-BAR, AND HOLE GAGES
Work for which Flush-pin Gages are Adapted Different Types of Flush-pin Gages Gage for Testing Direction of a Deep Drilled Hole Advantages of Flush-pin Gages Sliding bar Gages and Their Application Gages for Testing the Location of Holes 102-1 27

CHAPTER V
THREAD GAGES AND THEIR PRODUCTION PACES
Complete Gage Sets for Screws and Tapped Holes Special Forms of Thread Gages Tools for Cutting Gage Threads Gaging the Ends of Precision Thread-cutting Tools Methods of Grinding Tools to the Required Angle Tools for Cutting Whitworth Thread Gages Methods of Compensating for Errors in a Screw-cutting Lathe 128-151

CHAPTER VI
MAKING WHITWORTH THREAD GAGES
Machining of Gage Blanks Rough-machining the Thread Heat-treatment of the Gages Preliminary Grinding Operation on Thread Finish-grinding Operations 152-170

CHAPTER VII
GRINDING AND LAPPING THREAD GAGES
Advantages of Grinding Thread before Lapping General Types of Machines used for Thread Grinding Grinder having Traversing Master Screw Grinder having Traversing Wheel Slide Forming Wheel for Grinding Crest of Whitworth Thread Wheels used for Thread Gage Grinding Allowances for Lapping Timing the Lapping Periods Special Lapping Machines 1 71-200

CHAPTER VIII
LEAD AND DIAMETER MEASUREMENTS ON THREAD GAGES
Floating Micrometer for Diameter Measurements Determining Error in Thread Angle by Three-wire Method Testing Thread Gages for Lead Error Micrometer Type of Lead testing Machine Lead Tester equipped with Micrometer and Dial Gage Lead-testing Machine having Multiplying Indicator and Size-block Adjustment Fluid-gage Type of Lead Tester Lead-measuring Machines having Sliding Contact Point and Provision for Magnifying Errors Improved Design of Optical Lead-measuring Apparatus , 201-232

CHAPTER IX
MICROSCOPIC MEASURING MACHINES FOR TESTING ACCURACY OF CONTOUR AND THREAD GAGES PAGES
Microscopic Machine having Gage Adjustment Contour and Radius-measuring Instrument Measurements of Screw Threads Microscopic Measuring Machine having Micrometer Screw Adjustment Examples illustrating use of Microscopic Measuring Machines 233-252

CHAPTER X
PROJECTION METHOD OF TESTING GAGE THREADS
Optical Projection Apparatus and Its Application to Plug and Ring Gages Tracings of Inaccurate Thread Forms Photographing Thread Forms Vertical Projector for Screw Threads Thread Angle Projection Apparatus 253-271

CHAPTER XI
GENERAL GAGE-MAKING PRACTICE
Steel for Gages Grinding Snap Gages Gage Grinding Machines Grinding End-measuring or Pin Gages Heat treatment of Machine and Tool-steel Gages Methods of Hardening Gages to Prevent Distortion and Breakage Restoring Worn Gages by Electroplating Taper and Angle Gages 272-305