Shop practice for home mechanics, use of tools, shop processes, construction of small machines. Contains a chapter also on theoretical mechanics and on miscellaneous information relative to shop work

Front matter

SHOP PRACTICE

FOR HOME MECHANICS

YATES

Preface

Long before the author was asked to prepare this vohime on shop practice for home mechanics, he had a well-formed conception of just Avhat such a book ought to cover and how the subject-matter ought to be presented. Having started to dabble in amateur mechanics at the tender age of fourteen, he often found himself in dire need of some handy reference on shop processes — processes that could be employed about the small shop without elaborate equipment and great expense. Peculiar enough there has been no book, to the writer's knowledge, that covers this field. It was this fact that caused him to think so much about the preparations of such a book before the opportunity to Avrite it actually presented itself.

An examination of the current volumes concerning shop practice reveals nothing of real Avorth to the amateur; they ignore his little problems and trials that he meets in the routine of his small shop. The information relates to large, costly machines and appliances. The real amateur has little use for data concerning turret lathes, cylindrical grinders and broaching machines. He is, however, generally hungry for information that ^vl\\ help him to do better Avork in the easiest and best way.

A word about the subject-matter. It has been arranged progressively so that the beginner can study the book just as he Avould study a book on elementary chemistry. The first chapter, although theoretical in its aspect, has a distinct relationship to elementary mechanics, and the

6 Preface

reader is advised to give it careful attention. It deals with those great fundamentals upon which the Avhole science of mechanics rests. The following chapters treat simple shop operations and the use of small tools. The lathe is covered in detail as this is the most important tool in the shop, without which little can be done in the way of serious work. Such operations as grinding, hardening and tempering steel, pattern making, soldering, etc., are included, as the amateur must be proficient in all of these branches of his work. The last chapter contains such information and data as the author felt could be used advantageously in general shop routine. Some of the matter contained in this chapter was suggested by questions asked by the readers of Everyday Engineering Magazine, which the author, as editor of this journal, was called upon to answer.

The author Avishes to have the readers know that he is indebted to Mr. R. H. Wagner for the splendid design of the small brass smelting furnace described in Chapter IX; also to Mr. Homer Trecartin for reliable data on gears, and to his friend and counsellor, Mr. Dmght S. Simpson, for the useful table on A. S. M. E. thread standards.

It is hoped that this work will merit the approval of that multitude of amateur mechanics in America who work diligently in their little shops for no other reason than an unquenchable desire to ''make things."

Raymond Francis Yates.

June, 1920

Introduction To The Study Of Elementary Mechanics

The three states of matter — Energy — Power — Work — Force — Application of force to matter — The lever — Pulleys — Inclined plane — The wedge — The screw — Friction — Lubrication — Gravity — Momentum — Mass — Velocity — Gears — Gear problems — How to figure for gear strength — Calculation of power — Strength of gears — Gear tables — Gear speeds — Coefficient of cubical expansion — Coefficient of linear expansion — Apparatus to indicate linear expansion — Apparatus to indicate cubical expansion — How to figure linear expansion Pages 15-47

Chapter II

Different kinds of hammers — Choice of hammers — Files — Choice of files — Classification of files — Use of files — Flat filing — Draw filing — Round filing — Scrapers — How to make scrapers — Proper use of scrapers — Vises — The vise used as a press — Vise jaws — Making soft jaws — Screw drivers — Choice of screw drivers — Hack saws — How to use hack saws — Center punches — Making center punches — Driving punches — Riveting punches — Chisels — Classification of chisels — Use of chisels — Taps — Dies — Use of taps — Use of dies — Pliers — Parallel jaw pliers — Use of pliers — Wrench — Different kinds of wrenches — Anvils — Use of anvil — Clamps — Types of clamps — Use of clamps in different work — Manipulations of miscellaneous tools Pages 48-84

Chapter III Measuring Instruments And Their Use

The standards of measurement — American standards — The scale — The square — Use of the square — Adjustable squares — Calipers—

8 Contents

Inside calipers — Outside calipers^Shoulder calipers — Use of different types of calipers — Odd measurements made with calipers — Dividers — Use of dividers — Marking out with dividers — The micrometer^Construction of micrometer — How to read a micrometer — How to take care of a micrometer — Micrometer vernier — Micrometer vernier and how to read it — Vernier calipers — - How to read vernier calipers — Use of vernier calipers as height gauge — Surface gauges — Use of surface gauges — Surface plates — Marking out with surface plates — Protractors — Use of protractors in marking out — Use of miscellaneous measuring tools.

Chapter IV

Laying out and marking work — Twist drills — Operation of twist drills — How to properly sharpen twist drills — Twist drill sizes — How to sharpen very small twist drills — Drill presses for the small home shop — Operation of drill presses — Different types of drill presses — Power drill presses — Hand drill presses — The process of drilling — Finding the center for a large drill — Drilling different metals — How to sharpen the drill for brass — How to sharpen drill for iron and steel — Speed of twist drill for the different metals and different sized drills — Vee blocks — Use of Vee blocks in drilling holes in circular pieces — Fly cutter — Use of fly cutter — How to make a fly cutter — Bottoming drill — Use of bottoming drill — Countersink — Producing square holes — Use of drift — Construction of drift — Reamers — Use of reamers — Sharpening reamers — Burring reamers Pages 105-126

Chapter V Introduction To Lathe Work

Operation of the lathe — Simple lathes — Names of lathe parts for simple lathe — Lathe speed — Lathe tools — How to use lathe tools — How to sharpen lathe tools — Lathe dog — Turning simple work — Mounting work in lathe — Using simple lathe attachments — Use of face plate — Mounting work on face plate — Turning brass — How to sharpen tool for brass — Turning steel— Lathe chucks — Drilling on lathe — Slide rest and its use in turning — How to sharpen the various lathe tools — Lathe hand tools — Lathe power tools — General information on the operation, construction .and use of simple lathes Pages 127-140

Contents 9

CHAPTER YI ADVANCED LATHE WORK

Larger lathes — Description of lathe parts — Lathe saddle — Tailstock — Use of tailstock — Headstock — Slide rest — Use of slide rest — Cross slide — Center rest — Use of center rest — Live center — Dead center — How to take care of centers — Pulleys — Lathe speed — Back gears — Use of back gears for various speeds — Live center — Dead center — Grinding centers — Mounting w^ork between centers — Lathe chuck — Lubrication and care of lathe — Setting up and driving the lathe — Power required — Setting up line shaft and countershaft — Lathe swing — Shaft hangers — Speed of line shaft — Mounting of power motor — Bench lathes — Simple turning — Boring cylinders — Machining crankcase — Making bearings — Machining odd shaped pieces of work — Use of face plate — Use of blocks and clamping bolts — Use of angle plate — Mounting casting of angle plate for machining — Turning sheet metal — Turning eccentrics — Use of mandrels — Eccentric mandrels — Turning flywheels — Boring bars — Boring tools — Use of boring bars — Turning crankshafts — Turning four-throw crankshaft — Making built-up crankshaft — Thrust bolts — Screw cutting — Placing gears for screw cutting — Grinding and mounting tools for screw cutting — Thread gauges Pages 141-195

Chapter VII

Boring long holes — Use of D-bits — Construction of D-bits — Mounting gun barrel for drilling — Use of D-bit in drilling gun barrel — Reamer to follow D-bit — Cutting key-way on the lathe without milling attachment — Construction of special drilling attachment for use on small lathe — Construction and use of overhead drive for small lathe — Construction of small milling attachment for use on home shop lathe — Milling without milling attachment — Use of various milling devices — Use of special reamers — Home-made lathe tools for special purposes Pages 196-213

CHAPTER YIII

Grinding and polishing head — Choosing small grinder for shop use — Speed for grinding work — Proper speed for polishing M^ork —

10 Contents

Driving the grinding head — Abrasive wheels — Physical characteristics of abrasive wheels and abrasives — Explanation of grit — Grade — Bond — Special grades — Choosing wheels for different work — Wheel faces — Precautions in mounting wheels — Testing wheels before mounting — Maintaining wheel faces — Restoring wheel faces — Dressing wheels — Simple wheel dresser — Grinding — Lapp grinding — Use of the lathe as a lapp grinder — Abrasive paper — Abrasive cloth — Lapp board — Simple grinding appliances — Abrasive powders — Abrasive grains — Use of powders and grains — Bufifing — Buffing materials Pages 214-228

Chapter IX Pattern Making

How patterns are used — Making moulds — How casting is accomplished by the use of patterns — Moulding board — Cope — Drag — ■ Use of cope — Use of drag — Procedure in making mould — Tools required in moulding — Tools required in pattern making — Making patterns — Simple patterns — Split patterns — Woods used in making patterns — Shrinkage of metals — Draught — Laminated patterns — Fillets — Method of making fillets — Cored patterns — Core boxes — Making core boxes— Furnace for melting brass and bronze in the home shop — Construction of furnace — Construction of burner — Gasolene tank — Use of furnace Pages 229-244

Chapter X

How steel is hardened — Essential requirements for proper hardening — Tempering — Necessary temperature — Apparatus required — Decalescense point — Recalescense point — Tempering steel — Different temperatures — Quenching — Quenching baths — Case hardening — Apparatus for case hardening — Temperature for case hardening — Materials required for case hardening — Home-made hardening furnace — Construction of home-made hardening furnace Pages 245-254

Chapter XI

Theory of soldering — Preparation of surfaces before applj'ing solder ■ — Fluxes — Fluxes for various metals — Making flux — Solders — Composition of solders — Solders with various melting points —

Contents 11

Soldering coppers — Heating soldering coppers — Blow torches — Operation of blow torches — Use of Bunsen burner in soldering — Silver soldering — Silver soldering fluxes — Silver soldering apparatus — Application of silver solder — Silver soldering various metals — Brazing — Brazing various metals Pages 255-266

Chapter XII Construction Of Small Power Driven Press

Design ^ of machine — Drawings — Making the necessary patterns — Boring the spindle arm — Boring out table — Method of holding castings to lathe for boring — Use of special boring tool — Drilling — Boring bench clamp — Drilling spindle bearing — Reaming out spindle bearing — Machining pulleys on mandrel — Tapering pulleys — Cutting keyway in spindle — ^Tapping — Polishing — Scraping — Finishing parts — Assembling Pages 267-293

Chapter XIII Construction Of A Small Grinding Head

Patterns — Design — Castings — Preparation of castings for machining — Drilling the main casting — Machining pulley — Turning bearing — Making shaft — Machining flange — Finishing — Assembly.

Chapter XIV

How to read mechanical drawings — General or assembly drawings — • Detail drawings — Sectional drawings — Lines and what they mean — Abbreviations — A. S. M. E. screw standards — Drills to use for taps — S. A. E. standards — Grinding wheel grades — Table of allowances for driving, running forced and pushed fits — Miscellaneous mathematical information Pages 301-314

CHAPTER I Introduction to the Study of Elementary Mechanics

The three states of matter — Energy — Power — Work — Force — Application of force to matter — The lever — Pulleys — Inclined plane — The wedge — The screw — Friction — Lubrication — Gravity — Momentum — Mass — Velocity — Gears — Gear problems — How to figure for gear strength — Calculation of power — Strength of gears — Gear tables — Gear speeds — Coefficient of cubical expansion — Coefficient of linear expansion — Apparatus to indicate linear expansion — Apparatus to indicate cubical expansion — How to figure linear expansion.

A STUDY of the fundamentals of theoretical mechanics serves as a helpful introduction to the study of shop practice and processes. The great science of mechanics is based upon a few simple principles that are involved in every process or operation carried on in the shop. An understanding of these cardinal principles, even though it is an elementary one, will broaden the vision of the reader in mechanical matters and prepare him to carry on the study of shop practice more intelligently.

Matter is defined as that which occupies space. Matter exists in three states; solid, liquid and gaseous. Therefore, the science of mechanics is divided into the mechanics of solids, liquids and gases. Owing to the fact that the mechanics of liquids and gases are more or less remote from the realm of practical mechanics, the discussion of these particular phases will end here. The mechanics of solids will constitute the subject-matter of the ensuing paragraphs.

The terms energy, power, force and work are intimately connected with the science of mechanics. The reader is cautioned not to he too presumptuous in deciding the real meaning of these terms. It is a common, but none the less serious, error to assume that these terms are analogous. In everyday terminology they are, but in scientific parlance they take on a very special and specific meaning.

Energy is present in six different forms; kinetic, potential, electric, chemical, 'heat, and magnetic. Energy can be readily transformed from one form into another. • Through the agency of the electric battery, chemical energy is transformed into electric energy, and the potential energy in a coiled spring is changed to kinetic energy when the spring is released. Energy is never transformed from one form to another without a serious loss. In the steam-electric power plant, for instance, the loss of energy through transformation is enormous. The chemical energy released by the combustion of the coal under a boiler is converted into kinetic energy through the medium of steam and the steam engine or turbine. This kinetic energy again suffers a transformation into electrical energy through the medium of the generator. By this series of transformations, but a comparatively small percentage of the original chemical energy released by the burning coal is available in the form of useful electrical energy at the terminals of the generator.

The energy that is lost in transformation is only lost insofar as man is unable to recover it. Energy, like matter, is absolutely indestructible. It cannot be destroyed

Introduction to Study of Elementary Meclianics 15

in any known manner. The laws concerning tnis phase of science are called the laws of the conservation of energy. AVhen one ball strikes another on the billiard table, most of the kinetic energy possessed by the first l)all is imparted to the second one. The sudden impact causes a certain amount of the original energy to be transformed into heat. A part is also lost in the production of sound waves.

In the study of theoretical mechanics, force is recognized as that which tends to produce or modify motion. Force is usually measured in pounds. A force always has a certain direction, point of application and magnitude.

Work, although closely allied to force, has a different meaning. Work is performed when a force produces motion in overcoming resistance. Work really consists of two elements, force and motion. Force may be applied, but, unless motion is produced, no icorh results. In calculating work done, the magnitude of the force applied is measured in pounds and the distance moved in feet. This method of calculation has brought forth the term foot-pound which is the product of force (in pounds) and distance (in feet). Work = force x distance.

Power is the amount of work done in a given time. It is generally expressed in foot-pounds per minute or second. Power can be defined as the product of force and distance divided b}^ time. If 33,000 pounds are raised one foot in one minute, one horsepower is expended. To calculate power, it is necessary to divide the number of foot-pounds of work done in one minute by 33,000. Thus, if 66,000 pounds are raised one foot in one minute, 66,000 -^ 33,000 = 2 horsepower.

Velocity is the rate of motion — the distance covered divided by time. It is generally expressed in feet per minute or second. The calculation of velocity does not include either force or weight. If a body moves 6,000 feet in 6 minutes, its velocity will be 1,000 feet per minute.

Fig. I — The representation of forces graphically

The application of force to matter is one of the most important phases of theoretical mechanics. In Fig. 1, the body A has been moved from B to C in the direction of the arrow. The applied force is represented graphically by the straight line. The arrow gives the direction, the length of the line represents the magnitude and the end of the line the point at which the force was applied. It will be seen that the longer the line is, the greater the

Fig. 2 — Two equal forces acting in opposite directions will not produce motion

magnitude or value of the applied force because it would require a greater force to move the body A one inch than it would to move it a half inch. The graphical representation of forces is a great aid to the study of applied forces.

In Fig. 2, it will be noticed that two forces have been applied to the body A, each in an opposite direction. This is a case of opposed forces. If the forces B and C

A rs

^H m m

^B

B

Fig. 3 — The line D represents the resultant of the two forces B and C

are equal, the body A will not move. However, if one force is greater than the other, the body will move a distance equivalent to the difference in the applied forces. This is in accordance with the laws of the conservation of energy.

Fig. 4 — The graphic representation of the resultant force of two forces of unequal value acting in the same direction

If two forces act in the same direction the value of the resultant force will be equal to their sum. This is diagramed in Fig. 3. The force B is greater than C, but it will be seen that both forces are applied in the same direetion. Such forces are called parallel forces. The line D represents the resultant force, the sum of the forces B and C. If two forces act on a body in different directions as shown in Fig. 4 the resultant force can be represented by the line AB.

The study of forces and their application is an im-

Power Arm-

Weight Arm---

Fulcrum

Fig. 5 — A lever of the first class

Weight portant one oAving to its relationship to mechanics. Every part of a machine moves as a result of applied force. Many important illustrations of applied force can be made bv the use of the lever. The lever is a solid

Fores

Wei(^hf

Fig. 6— A lever of the second class

rod mounted or resting upon a point called the fulcrum. The lever shown in Fig. 5 is called a lever of the first class. It is divided into three parts ; the fulcrum, already mentioned, the weight arm and the power arm. It will be seen that the power arm is that portion to which the force is applied, while the weight arm is that part supporting the weight. The second-class lever has the weight between the fulcrum and the force as showni in Fig. 6. A lever of the third class has the force applied between the weight and the fulcrum, as shoMTi in Fig. 7. Tlie fundamental law of the lever is the same for all classes, first, second and third.

To find the power of a lever of the first class (Fig. 5), the weight should be multiplied by its distance from the fulcrum and divided by the distance of the force or power from the fulcrum. The problem presented in Fig. 8 would be solved as follows:

= 4 lbs.

From this example it will be seen that the greater the distance betAveen the fulcrum and the applied power and •the shorter the distance between the fulcrum and the

A

Weight

Fig. 7 — A lever of the third class

weight, the more powerful the lever will be. In fact, the power of the lever is practically infinite. Aristotle was one of the first early scientists to recognize the great power of the lever.

If it is desired to calculate the weight on a lever knowing the distance it is located from the fulcrnm, the force applied and the distance of the force from the fulcrum, the following mathematical practice is emiiloyed. The

-/2"-

6 Lbs.

4 it's.

Fig. 8 — A practical problem of the lever

factors of the problem are presented in Fig. 9. Here it will be noticed that the weight is located 30 inches from the fulcrum, while the force of 50 pounds is applied 5 inches from the fulcrum. The correct answer mil result n l\

50 Lbs

S'/iLbs.

Fig. 9 — Another practical problem of the lever from the process of multiplying the power by its distance from the fulcrum and dividing by the distance of the weight from the fulcrum.

Mathematical problems involving the lever could be extended indefinitely but the author feels that the few problems given will suffice to give the reader a sound elementary understanding of this particular phase of the subject.

A compound lever is sho^n in Fig. 10. This is a system of levers where the power arm of one rests on the weight arm of another. A very small force applied to the point A will support a comparatively large weight at B. To find the power exerted at A for the support of a specific weight at B, the weight is multiplied by the product of the short arms and divided by the product of the long arms.

To carry the explanation of the lever further, reference

Fig. lo — A compound lever is made to Fig. 11. A force acting upon a body tends to produce motion either in a straight or circular line. The first is called a motion of translation, the second, a motion of rotation. The lever in Fig. 11 is pivoted at A and any force acting upon it (except one which would pass through the center of the pivot as indicated by the line B) would tend to produce a rotary motion. The tendency toward rotational movement will depend upon two factors, i.e., the magnitude of the force and its distance from the pivot when measured along a line that will be at exact right angles to the line of action of the force. It will be seen that a line measured at right angles to the force, in case of the force passing through the center of the pivot, Avould not involve the lever at all and therefore a rotan^ movement would not be produced. If a force of ten pounds is applied to the lever at F, its moment (moment in mechanics means the measure of the turning effect of a force which has a tendency to produce a rotary motion) ^^dll be greater than it would be if the force was applied at the point G. This is in accordance mth the law stating that the rotary motion or noment

Fig. II — Analysis of the action of forces on a simple lever

will depend upon (1) the magnitude of the force and (2) its distance from the pivot or center of motion. It will be noticed that the distance E is less than the distance C from the center of the lever, therefore the rotary effect of the force acting at point G A\dll be less than that acting at point F. If the lever is in the position indicated by the dotted lines and a force of 10 lbs. is acting upon it in the direction K, it will be found that the effective distance D is much less than the distance C when the lever was in the other position. For this reason the force, although the same in both cases, will not be as effective. In each of the cases cited, it will be seen that the actual leverage is equal to the distance of the lines D, E and C. These lines are properly called the "lever arms of the moment." The actual moment can be calculated by multiplying the force by the perpendicular distance from the axis to the line representing the direction of the force. If the distance from F to the center of the axis or pivot A is 21/^ ft. and the force applied to the point F 10 lbs., the result in foot-pounds or the moment will be :

2.5 X 10 = 25 foot-pounds.

Mechanical movements are said to be positive or negative, depending upon their direction. If the lever in Fig.

Fig. 12 — The force A will produce motion of the wheel more readily

than the force B

11 is moving in the direction M, its rotation is said to be positive because it is moving clockwdse. A movement in the opposite direction is said to be negative or counterclockwise.

A wheel acts in much the same manner as a lever. Reference is made to Fig. 12. If a force A acted upon the wheel it would rotate and function in tlie manner of a continuous lever. It will be noticed that the tendency to rotate will be greater if the force is applied at the periphery. If a force B was applied, the tendency to rotate would be much less. In the case of the wheel shown in Fig. 13, no rotation or tendency toward rotation mil be noticed, owing to the fact that the whole system is in perfect equilibrium. It wdll also be seen that the wheel functions as a lever; the center acting as the fulcrum and the two sides as the weight and power arms. The

Fig. 13 — Two equal forces or weights suspended as shown will not

produce motion

weight is equal to the power and therefore no motion is produced.

A series of connected pulleys or v»'heels is called a train and the wheel which imparts the motion is called the driver. As a wheel functions as a continuous lever, a series or train of wheels will act as a system of compound levers. The lifting power of a series of pulleys is used to advantage many times. In Fig. 14, the rope A, and hence the force applied at the end, will move through twice the distance traveled by tlie weight B. Therefore the weight can be equal to t^^ice the force applied at the end of the rope. If another pulley is added to the system, a weight three times greater than the applied force can be lifted, but the distance traveled by the weight will be one-third of that traveled by the force acting at the end of the rope. A¥ith a system of seven pulleys, a weight seven times greater than the applied force can be lifted theoretically if the frictional losses are not considered. In this case, the weight moves through a distance that is one-seventh of that traveled by the force. With a sy?-

Fig. 14 — A simple system of two pulleys

tern of pulleys one man can lift many times his o^\av Aveight. If a system of six pulleys is used and the force applied at the end of the rope is equivalent to 50 lbs., it mil be possible to lift 6 x 50 or 300 lbs. If the end of the rope or the force passes through 60 feet, the weight will be lifted 1/6 of 60 or 60 - 6 = 10 feet.

The inclined plane takes an important part in the science of mechanics. The meaning of an inclined plane becomes apparent by referring to A, Fig. 15. A plane that is at an angle (except a right angle) with a horizontal plane is called an inclined plane. It will be understood that a smaller force is reqnired to move a given weight up an inclined plane than to move it perpendicularly. The nearer the inclined plane approaches the per-

A B C

F*g« 15 — Three inclined planes of different angles

pendieular, the greater the force necessary to move it must be. The weight on the inclined plane at B, Fig. 15, could be moved with a smaller force than would be necessary to move the same weight at C where the angle is