Precision locating and dividing methods

MACHINERY’S REFERENCE SERIES
EACH NUMBER IS ONE UNIT IN A COMPLETE LIBRARY OF MACHINE DESIGN AND SHOP PRACTICE REVISED AND REPUBLISHED FROM MACHINERY
NUMBER 135
CONTENTS
Copyright, 1914, The Industrial Press, Publishers of Machinery, 140-148 Lafayette Street, New York City
Machinery
The Leading Mechanical Journal
Machine Design Construction Shop Practice
THE INDUSTRIAL PRESS
140-148 Lafayette St. New York City 51-52 Chancery Lane, London
The degree of accuracy that is necessary in the construction of certain classes of machinery and tools, has made it necessary for toolmakers and machinists to employ various methods and appliances for locating holes or finished surfaces to given dimensions and within the prescribed limits of accuracy. In this treatise, various approved methods of locating work, such as are used more particularly in tool-rooms, are described and illustrated. These are not given, in every case, as being the best possible method under all conditions, because, as every mechanical man knows, the best way may be dependent upon the element of accuracy with little regard for the time required to do the work, or this order may be reversed; therefore, one method is seldom, if ever, the best under all circumstances, and it is necessary for the workman to consider the conditions in each case and then be guided by his judgment and experience in determining just how the work should be done.
Among the different methods employed by toolmakers for accurately locating work such as jigs, etc., on the faceplate of a lathe, one of the most commonly used is known as the “button method.” This method is so named because cylindrical bushings or buttons are attached to the work in positions corresponding to the holes to be bored, after which they are used in locating the work. These buttons which are ordinarily about ½ or ⅝ inch in diameter, are ground and lapped to the same size, and the ends are finished perfectly square. The outside diameter should preferably be such that the radius can easily be determined, and the hole through the center should be about ⅛ inch larger than the retaining screw so that the button can be adjusted laterally.