Listen to the AudioBook: Elementary lathe practice - As adapted to the teaching of machine shop practice in technical schools by T. J. Palmateer

Elementary Lathe Practice

AS ADAPTED TO THE TEACHING OF MACHINE SHOP PRACTICE IN TECHNICAL SCHOOLS.

BY T. J. PALMATEER INSTRUCTOR IN MACHINE WORK Leland Stanford Junior University

PREFACE

The object of this instruction book is to help beginners to acquire some familiarity with the more common lathe operations in the shortest practicable period of time. For this purpose three exercises have been designed with the view of giving the student the maximum amount of information in the small amount of time usually allowed for this purpose. The repetition of operations has therefore been avoided wherever it was considered advisable and the time lost in simply cutting off metal has been reduced as much as possible.

It is assumed that beginners will receive oral instruction on the manipulation of the lathe, as in shifting the belt, the feed control, etc. It will also be necessary for the instructor to give a practical demonstration of most of the operations.

The lathe speeds for the different operations as indicated in this book are only approximately correct since the actual cutting speed of the tool in feet per minute varies with the size and kind of lathe used. The instructor is expected to designate the proper speeds although the belt connections given herein will generally be close enough for beginners.

In case it is considered advisable to devote to the elementary lathe operations less time than would be necessary to complete the three exercises presented herein, very good results can be obtained if the student will read all of the instructions carefully and then do only Exercise No. 1 and piece B of Exercise No. 3.

The instructions here given are not intended as fixed rules for it is recognized that some of the operations may be done by other methods with equally good results.

T. J. PALMATEER.

Stanford University, Cal. January 1917.

EXERCISE No. 1.

FIT SHAFT TO COLLAR—RUNNING FIT

Cut off with a power hack-saw a piece of steel 6¹⁄₁₆ inches long from a bar 1 inch in diameter. This will allow ¹⁄₁₆ of an inch for finishing the ends and ³⁄₁₆ of an inch for turning the diameter.

An experienced lathe operator would use a piece of steel ⅝ of an inch in diameter, but for beginners it is better to use larger stock to allow for practice turning.

CENTERING

Center both ends in the centering machine. The size of the center in this shaft should be from ³⁄₁₆ to ¼ of an inch in diameter. Larger work should have deeper centers.

If a centering machine is not available, the work may be centered by first locating the center with a pair of dividers and center punch and then using a combination drill and countersink in the lathe as shown in Fig. 1. In this case the work is held by hand to prevent it from turning. As this work is to be turned, it is necessary to center it only approximately true.

Accurate Centering.—When the work is to be centered accurately, it may be done by putting one end in the lathe chuck and the other in a steady rest. A pointed tool is then used in the tool post as shown in Fig. 2. The point of this tool has an angle of 60 degrees, the same as the lathe centers, and is ground like a flat drill so that it cuts on both sides.

After the shaft is centered with this tool, a center hole about ⅛ of an inch in diameter should be drilled. This is done by holding the drill in the tail-stock of the lathe with a drill-chuck, as shown in Fig. 3. The object of this center hole is to give the center of the shaft a bearing on the lathe center a short distance back from the point, as at A in Fig. 4.

PLACING WORK IN LATHE

The work is made to rotate on the lathe centers by fastening a lathe dog to the shaft at the head-stock end, as shown at A in Fig. 5.

The tail-

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