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THE "HOW-TO-DO-IT" BOOKS
PRACTICAL MECHANICS FOR BOYS
THE "HOW-TO-DO-IT" BOOKS
PRACTICAL MECHANICS
FOR BOYS
In language which every boy can understand
and so arranged that he may readily carry
out any work from the instructions given.
WITH MANY ORIGINAL ILLUSTRATIONS
By J. S. ZERBE, M.E.
_Author of_
CARPENTRY FOR BOYS
ELECTRICITY FOR BOYS
M. A. DONOHUE & COMPANY
CHICAGO :: NEW YORK
COPYRIGHT, 1914, BY
THE NEW YORK BOOK COMPANY
Made in U. S. A.
CONTENTS
INTRODUCTORY Page 1
I. ON TOOLS GENERALLY Page 7
Varied Requirements. List of Tools. Swivel Vises. Parts of Lathe.
Chisels. Grinding Apparatus. Large Machines. Chucks. Bench Tools.
Selecting a Lathe. Combination Square. Micrometers. Protractors.
Utilizing Bevel Protractors. Truing Grindstones. Sets of Tools. The
Work Bench. The Proper Dimensions. How Arranged.
II. HOW TO GRIND AND SHARPEN TOOLS Page 26
Importance of the Cutting Tool. The Grinder. Correct Use of Grinder.
Lathe Bitts. Roughing Tools. The Clearance. The Cutting Angle. Drills.
Wrong Grinding. Chisels. Cold Chisels. System in Work. Wrong Use of
Tools.
III. SETTING AND HOLDING TOOLS Page 34
Lathe Speed. The Hack-saw. Hack-saw Frame. The Blade. Files.
Grindstones. Emery and Grinding Wheels. Carelessness in Holding Tools.
Calipers. Care in Use of Calipers. Machine Bitts. The Proper Angle for
Lathe Tools. Setting the Bitt. The Setting Angle. Bad Practice. Proper
Lathe Speeds. Boring Tools on Lathe. The Rake of the Drill. Laps. Using
the Lap. Surface Gages. Uses of the Surface Gage.
IV. ON THE FIRST USE OF THE FILE Page 48
The First Test. Filing an Irregular Block. Filing a Bar Straight.
Filing Bar with Parallel Sides. Surfacing Off Disks. True Surfacing.
Precision Tools. Test of the Mechanic. Test Suggestions. Use of the
Dividers. Cutting a Key-way. Key-way Difficulties. Filing Metal Round.
Kinds of Files. Cotter-file. Square. Pinion. Half-round. Round.
Triangular. Equalizing. Cross. Slitting. Character of File Tooth.
Double Cut. Float-cut. Rasp Cut. Holding the File. Injuring Files.
Drawing Back the File.
V. HOW TO COMMENCE WORK Page 61
Familiarity with Tools. File Practice. Using the Dividers. Finding
Centers. Hack-saw Practice. Cutting Metal True. Lathe Work. First
Steps. Setting the Tool. Metals Used. The Four Important Things.
Turning Up a Cylinder. Turning Grooves. Disks. Lathe Speeds.
VI. ILLUSTRATING SOME OF THE FUNDAMENTAL DEVICES Page 68
Belt Lacing. Gears. Crown Wheel. Grooved Friction Gearing. A Valve
which Closes by the Water Pressure. Cone Pulleys. Universal Joint.
Trammel for Making Ellipses. Escapements. Simple Device to Prevent a
Wheel or Shaft from Turning Back. Racks and Pinions. Mutilated Gears.
Simple Shaft Coupling. Clutches. Ball and Socket Joints. Tripping
Devices. Anchor Bolt. Lazy Tongs. Disk Shears. Wabble Saw. Crank Motion
by a Slotted Yoke. Continuous Feed by Motion of a Lever. Crank Motion.
Ratchet Head. Bench Clamp. Helico-volute Spring. Double helico-volute.
Helical Spring. Single Volute Helix Spring. Flat Spiral, or Convolute.
Eccentric Rod and Strap. Anti-dead Center for Lathe.
VII. PROPERTIES OF MATERIALS Page 79
Elasticity. Traction. Torsion. Flexure. Tenacity. The Most Tenacious
Metal. Ductility. Malleability. Hardness. Alloys. Resistance.
Persistence. Conductivity. Equalization. Reciprocity. Molecular Forces.
Attraction. Cohesion. Adhesion. Affinity. Porosity. Compressibility.
Elasticity. Inertia. Momentum. Weight. Centripetal Force. Centrifugal
Force. Capillary Attraction. The Sap of Trees. Sound. Acoustics. Sound
Mediums. Vibration. Velocity of Sound. Sound Reflections. Resonance.
Echos. Speaking Trumpet. The Stethoscope. The Vitascope. The
Phonautograph. The Phonograph. Light. The Corpuscular Theory.
Undulatory Theory. Luminous Bodies. Velocity of Light. Reflection.
Refraction. Colors. The Spectroscope. The Rainbow. Heat. Expansion.
VIII. HOW DRAUGHTING BECOMES A VALUABLE AID Page 95
Lines in Drawing. Shading. Direction of Shade. Perspectives. The Most
Pronounced Lines. Direction of Light. Scale Drawings. Degree, and What
it Means. Memorizing Angles. Section Lining. Making Ellipses and
Irregular Curves. Focal Points. Isometric and Perspective. The
Protractor. Suggestions in Drawing. Holding the Pen. Inks. Tracing
Cloth. Detail Paper. How to Proceed. Indicating Material by Section
Lines.
IX. TREATMENT AND USE OF METALS Page 112
Annealing. Toughness and Elasticity. The Process. Tempering. Tempering
Contrasted with Annealing. Materials Used. Gradual Tempering. Fluxing.
Uniting Metals. Alloying Method. Welding. Sweating. Welding Compounds.
Oxidation. Soldering. Soft Solder. Hard Solder. Spelter. Soldering
Acid. The Soldering Iron.
X. ON GEARING, AND HOW ORDERED Page 121
Spur and Pinion. Measuring a Gear. Pitch. Diametral Pitch. Circular
Pitch. How to Order a Gear. Bevel and Miter Gears. Drawing Gears.
Sprocket Wheels.
XI. MECHANICAL POWER Page 128
The Lever. Wrong Inferences from Use of Lever. The Lever Principle.
Powers vs. Distance Traveled. Power vs. Loss of Time. Wrongly-Directed
Energy. The Lever and the Pulley. Sources of Power. Water Power.
Calculating Fuel Energy. The Pressure or Head. Fuels. Power from Winds.
Speed of Wind and Pressure. Varying Degrees of Pressure. Power from
Waves and Tides. A Profitable Field.
XII. ON MEASURES Page 139
Horse Power. Foot Pounds. Energy. How to Find Out the Power Developed.
The Test. Calculations. The Foot Measure. Weight. The Gallon. The
Metric System. Basis of Measurement. Metrical Table, Showing
Measurements in Feet and Inches.
XIII. USEFUL INFORMATION FOR THE WORKSHOP Page 148
Finding the Circumference of a Circle. Diameter of a Circle. Area of a
Circle. Area of a Triangle. Surface of a Ball. Solidity of a Sphere.
Contents of a Cone. Capacity of a Pipe. Capacity of Tanks. To Toughen
Aluminum. Amalgams. Prevent Boiler Scaling. Diamond Test. Making Glue
Insoluble in Water. Taking Glaze Out of Grindstone. To Find Speeds of
Pulleys. To Find the Diameters Required. To Prevent Belts from
Slipping. Removing Boiler Scale. Gold Bronze. Cleaning Rusted Utensils.
To Prevent Plaster of Paris from Setting Quickly. The Measurement of
Liquids with Spoons.
XIV. SIMPLICITY OF GREAT INVENTIONS AND OF NATURE'S MANIFESTATION
Page 152
Invention Precedes Science. Simplicity in Inventions.
The Telegraph. Telephone. Transmitter. Phonograph.
Wireless Telegraphy. Printing Telegraph. Electric Motor.
Explosions. Vibrations in Nature. Qualities of
Sound. The Photographer's Plate. Quadruplex Telegraphy.
Electric Harmony. Odors. Odophone. A Bouquet
of Vibrations. Taste. Color.
XV. WORKSHOP RECIPES AND FORMULAS Page 160
Adhesives for Various Uses. Belt Glue. Cements. Transparent Cement. U.
S. Government Gum. To Make Different Alloys. Bell-metal. Brass.
Bronzes. Boiler Compounds. Celluloid. Clay Mixture for Forges. Modeling
Clay. Fluids for Cleaning Clothes, Furniture, etc. Disinfectants.
Deodorants. Emery for Lapping Purposes. Explosives. Fulminates. Files,
and How to Keep Clean. Renewing Files. Fire-proof Materials or
Substances. Floor Dressings. Stains. Foot Powders. Frost Bites. Glass.
To Frost. How to Distinguish. Iron and Steel. To Soften Castings.
Lacquers. For Aluminum and Brass. Copper. Lubricants. Paper.
Photography. Plasters. Plating, Coloring Metals. Polishes. Putty. Rust
Preventives. Solders. Soldering Fluxes. Steel Tempering. Varnishes.
Sealing Wax.
XVI. HANDY TABLES Page 178
Table of Weights for Round and Square Steel. Table of Weight of Flat
Steel Bars. Avoirdupois Weight. Troy Weight. Apothecaries' Weight.
Linear Measure. Long Measure. Square Measure. Solid or Cubic Measure.
Dry Measure. Liquid Measure. Paper Measure. Table of Temperatures.
Strength of Various Metals. Freezing Mixtures. Ignition Temperatures.
Power and Heat Equivalents.
XVII. INVENTIONS AND PATENTS, AND INFORMATION ABOUT THE
RIGHTS AND DUTIES OF INVENTORS AND WORKMEN,
Page 188
The Machinist's Opportunities. What is an Inventor? Idea Not Invention.
What an Invention Must Have. Obligation of the Model Builder. Paying
for Developing Devices. Time for Filing an Application. Selling an
Unpatented Invention. Joint Inventors. Joint Owners Not Partners.
Partnerships in Patents. Form of Protection Issued by the Government.
Life of a Patent. Interference Proceedings. Concurrent Applications.
Granting Interference. Steps in Interference. First Sketches. First
Model. First Operative Machine. Preliminary Statements. Proving
Invention. What Patents Are Issued For. Owner's Rights. Divided and
Undivided Patents. Assignments. How Made. What an Invention Must Have.
Basis for Granting Patent in the United States. Reasons for Granting
Abroad. Original Grants of Patents. International Agreement.
Application for Patents. Course of Procedure. Costs. Filing a Matter of
Secrecy.
LIST OF ILLUSTRATIONS
FIG. PAGE
1. Bench vise 8
2. Pipe grip for vise 9
3. Swivel vise 10
4. Speed lathe 11
5. Calipers 12
6. Engine lathe 13
7. Center gage 14
8. Pocket screw and wire gage 15
9. Handy bench vise 16
10. Combination square 17
11. Uses of the combination square 18
12. A quick adjusting micrometer 19
13. Universal bevel protractor 20
14. Uses of universal bevel protractor 21
15. Grindstone truing device 22
16. Set of tools and case 23
17. The work bench 24
18. Hook tool 28
19. Parting tool 28
20. Knife tool 28
21. Right-hand side tool 28
22. Internal tool 28
23. Left-hand side tool 28
24. Tool for wrought iron 29
25. Tool for cast iron 29
26. End view of drill 31
27. Side view of drill 31
28. Hack-saw frame 35
29. Hack-saw blade 35
30. Plain hook tool 38
31. Plain straight tool 38
32. Proper angles for tools 39
33. Angles for tools 39
34. Angles for tools 39
35. Set of the bitt 40
36. Correct angle 41
37. Wrong angle 41
38. Too low 42
39. Improper set 42
40. Internal set 43
41. Set for brass 43
42. Surface gage 44
43. Uses of surface gage 46
44. Rounded surface 49
45. Winding surface 49
46. Hexagon nut 51
47. Laying off hexagon nut 51
48. Cutting key-way 52
49. Key-seat rule 54
50. Filing metal round 54
51. Filing metal round 54
52. Making a round bearing 55
53. Making a round bearing 55
54. Cross section of file 56
55. Files 58
56. Correct file movement 59
57. Incorrect file movement 60
58. Belt lacing 69
59. Belt lacing 69
60. Belt lacing 69
61. Belt lacing 69
62. Bevel gears 71
63. Miter gears 71
64. Crown wheel 71
65. Grooved friction gears 71
66. Valve 71
67. Cone pulleys 71
68. Universal joint 71
69. Trammel 73
70. Escapement 73
71. Device for holding wheel 73
72. Rack and pinion 73
73. Mutilated gears 73
74. Shaft coupling 73
75. Clutches 75
76. Ball and socket joints 75
77. Fastening ball 75
78. Tripping devices 75
79. Anchor bolt 75
80. Lazy tongs 75
81. Disc shears 75
82. Wabble saw 76
83. Continuous crank motion 76
84. Continues feed 76
85. Crank motion 76
86. Ratchet head 76
87. Bench clamp 76
88. Helico-volute spring 77
89. Double helico-volute 77
90. Helical spring 77
91. Single volute-helix 77
92. Flat spiral or convolute 77
93. Eccentric rod or strap 77
94. Anti dead-centers for lathes 77
95. Plain circle 95
96. Ring 96
97. Raised surface 96
98. Sphere 96
99. Depressed surface 96
100. Concave 97
101. Forms of cubical outlines 98
102. Forms of cubical outlines 98
103. Forms of cubical outlines 98
104. Forms of cubical outlines 98
105. Shading edges 99
106. Shading edges 99
107. Illustrating heavy lines 100
108. Illustrating heavy lines 100
109. Lines on plain surfaces 101
110. Lines on plain surfaces 101
111. Illustrating degrees 102
112. Section lining 103
113. Drawing an ellipse 104
114. Perspective at angles 106
115. Perspective of cube 107
116. Perspective of cube 107
117. Perspective of cube 107
118. Protractor 108
119. Using the protractor 109
120. Section-lining metals 110
121. Spur gears 122
122. Miter gear pitch 123
123. Bevel gears 124
124. Laying of miter gears 125
125. Sprocket wheel 128
126. Simple lever 129
127. Lever action 130
128. The pulley 132
129. Change of direction 133
130. Change of direction 133
131. Steam pressure 135
132. Water pressure 135
133. Prony brake 141
134. Speed indicator 142
PRACTICAL MECHANICS FOR BOYS
INTRODUCTORY
The American method of teaching the mechanical arts has some
disadvantages, as compared with the apprentice system followed in
England, and very largely on the continent.
It is too often the case that here a boy or a young man begins work in a
machine shop, not for the avowed purpose of learning the trade, but
simply as a helper, with no other object in view than to get his weekly
wages.
Abroad, the plan is one which, for various reasons, could not be
tolerated here. There he is bound for a certain term of years, and with
the prime object of teaching him to become an artisan. More often than
otherwise he pays for this privilege, and he knows it is incumbent on
him "to make good" right from the start.
He labors under the disadvantage, however, that he has a certain tenure,
and in that course he is not pushed forward from one step to the next on
account of any merit of his own. His advancement is fixed by the time he
has put in at each part of the work, and thus no note is taken of his
individuality.
Here the boy rises step after step by virtue of his own qualifications,
and we recognize that one boy has the capacity to learn faster than
another. If he can learn in one year what it requires three in another
to acquire, in order to do it as perfectly, it is an injury to the apt
workman to be held back and deterred from making his way upwardly.
It may be urged that the apprentice system instills thoroughness. This
may be true; but it also does another thing: It makes the man a mere
machine. The true workman is a thinker. He is ever on the alert to find
easier, quicker and more efficient means for doing certain work.
What is called "Efficiency" in labor methods, can never obtain in an
apprenticeship system for this reason. In a certain operation, where
twelve motions are required to do a certain thing, and a minute to
perform the twelve operations, a simplified way, necessitating only
eight motions, means a difference in saving one-third of the time. The
nineteen hundred fewer particular movements in a day's work, being a
less strain on the operator, both physically and mentally, to say
nothing whatever of the advantages which the proprietor of the shop
would gain.
I make this a leading text in the presentation of this book; namely,
that individual merit and stimulus is something of such extreme
importance that it should be made the keynote for every boy who tries to
become a mechanic.
The machinist easily occupies a leading place in the multitude of trades
and occupations. There is hardly an article of use but comes to the
market through his hands. His labor is most diverse, and in his
employment doing machine work he is called upon to do things which vary
widely in their character.
These require special knowledge, particular tools, and more frequently
than otherwise, a high order of inventive ability to enable him to
accomplish the task.
The boy should be taught, at the outset, that certain things must be
learned thoroughly, and that habits in a machine shop can be bad as well
as good. When he once becomes accustomed to putting a tool back in its
rightful place the moment he is through with it, he has taken a long
step toward efficiency.
When he grasps a tool and presents it to the work without turning it
over several times, or has acquired the knack of picking up the right
tool at the proper place, he is making strides in the direction of
becoming a rapid and skilled workman.
These, and many other things of like import, will require our attention
throughout the various chapters.
It is not the intention of the book to make every boy who reads and
studies it, a machinist; nor have we any desire to present a lot of
useful articles as samples of what to make. The object is to show the
boy what are the requirements necessary to make him a machinist; how to
hold, handle, sharpen and grind the various tools; the proper ones to
use for each particular character of work; how the various machines are
handled and cared for; the best materials to use; and suggest the
numerous things which can be done in a shop which will pave the way for
making his work pleasant as well as profitable.
It also analyzes the manner in which the job is laid out; how to set the
tools to get the most effective work; and explains what is meant by
making a finished piece of workmanship. These things, properly acquired,
each must determine in his own mind whether he is adapted to follow up
the work.
Over and above all, we shall try to give the boy some stimulus for his
work. Unless he takes an interest in what he is doing, he will never
become an artisan in the true sense of the word.
Go through the book, and see whether, here and there, you do not get
some glimpses of what it means to take a pleasure in doing each
particular thing, and you will find in every instance that it is a
satisfaction because you have learned to perform it with ease.
I do not know of anything which has done as much to advance the arts and
manufactures, during the last century, as the universal desire to
improve the form, shape and structure of tools; and the effort to invent
new ones. This finds its reflection everywhere in the production of new
and improved products.
In this particular I have been led to formulate a homely sentence which
expresses the idea: Invention consists in doing an old thing a new way;
or a new thing any way.
THE AUTHOR.
CHAPTER I
ON TOOLS GENERALLY
Judging from the favorable comments of educators, on the general
arrangement of the subject matter in the work on "Carpentry for Boys," I
am disposed to follow that plan in this book in so far as it pertains to
tools.
In this field, as in "Carpentry," I do not find any guide which is
adapted to teach the boy the fundamentals of mechanics. Writers usually
overlook the fact, that as the boy knows nothing whatever about the
subject, he could not be expected to know anything about tools.
To describe them gives a start in the education, but it is far short of
what is necessary for one in his condition. If he is told that the
chisel or bit for a lathe has a diamond point, or is round-nosed, and
must be ground at a certain angle, he naturally wants to know, as all
boys do, _why_ it should be at that angle.
So in the setting of the tools with relation to the work, the holding
and manipulation of the file, of the drill for accurate boring, together
with numerous little things, are all taken for granted, and the boy
blunders along with the ultimate object in sight, without having the
pathway cleared so he may readily reach the goal.
VARIED REQUIREMENTS.--The machinist's trade is one which requires the
most varied tools of all occupations, and they are by all odds the most
expensive to be found in the entire list of vocations.
[Illustration: _Fig. 1. Bench Vise._]
This arises from the fact that he must work with the most stubborn of
all materials. He finds resistance at every step in bringing forth a
product.
LIST OF TOOLS.--With a view of familiarizing the boy with this great
variety the following list is compiled, from which we shall select the
ones essential in the initial equipment of a small shop.
VISES.--One small, good vise is infinitely preferable to two bad ones.
For ordinary work a 3-inch jaw is preferable, and it should be firmly
mounted on the bench. So many kinds are now made that it would be a
costly thing to purchase one for each special use, therefore the boy
will find it profitable to make some attachments for the ordinary vise.
[Illustration: _Fig. 2. Pipe Grip for Vise._]
SWIVEL VISES.--A swivel vise is always a good tool, the cost being not
excessive over the ordinary kind. Then a pair of grips for holding pipe,
or round material which is to be threaded, can readily be made.
The drawing (Fig. 2) shows a serviceable pair of grips, made to fit the
jaws of a vise, and will be acceptable in much of the work. Then, the
vise should be provided with copper caps for the jaws to be used when
making up articles which would otherwise be injured by the jaws.
[Illustration: _Fig. 3. Swivel Vise._]
Let us get a comprehensive view of the different kinds of tools
necessary in a fully equipped shop.
PARTS OF LATHE.--The first thing of importance is the lathe, and of
these there is quite a variety, and among the accompaniments are the
slide rest, mandrel, back gear, division plate, angle plate, cone plate
and various chucks.
There must also be change wheels, studs and quadrant plates, self-acting
feed for surfacing and cross slide, and clamping nuts.
Drilling machines, both hand and power, hand and ratchet braces and
breast-drill stocks.
[Illustration: _Fig. 4--Speed Lathe._]
CHISELS.--Chisels of various kinds, for chipping and cross-cutting;
round-nosed, centering, set punches, tommies and drifts.
Back, tee and centering square; bevels, spirit level, inside and outside
calipers, straight edges, rules and surface plates.
Gages for boring, scribing blocks, steel and brass scribes, stocks and
dies, screw-plates, taps for bolts, reamers.
[Illustration: _Fig. 5. Calipers_]
Files for various descriptions, countersinks, frame and hack saws.
GRINDING APPARATUS.--Emery wheel, cloth and paper, paper, flour emery,
polishing powders, laps and buffs, and polishing sticks.
[Illustration: _Fig. 6. Engine Lathe._
_A. Lathe Bed_
_B. Rack Gear_
_C. Live Center_
_D. Dead Center_
_E. Dead Spindle_
_F. Face Plate_
_G. Feed Screw_
_H. Train of Gears_
_I. Head Stock_
_J. Mandrel_
_K. Cone Pulley_
_L. Angle Plate for Tool Holder_
_M. Tool Post_
_N. Tail Stock_
_O. Wheel for Slide Rest Mechanism_
_P. Locking Lever for Tail Stock._]
Forge, anvils, tongs, swages, punches, bolt tools, hot and cold chisels,
blow-pipe, soldering iron, hard and soft solders, borax, spirits of
salts, oil, resin and spelter.
To this may be added an endless variety of small bench tools,
micrometers, protractors, arbors, collets, box tools and scrapers.
[Illustration: _Fig. 7. Center Gage._]
LARGE MACHINES.--The list would not be complete without the planer,
shaper and milling machine, with their variety of chucks, clamps and
other attachments, too numerous to mention.
The foregoing show what a wonderful variety of articles are found in a
well-equipped shop, all of which can be conveniently used; but to the
boy who has only a small amount of money, a workable set is indicated as
follows:
A small lathe, with an 8-inch swing, can be obtained at a low cost,
provided with a countershaft complete.
CHUCKS.--With this should go a small chuck, and a face-plate for large
work, unless a large chuck can also be acquired. This, with a dozen
tools of various sizes, and also small bits for drilling purposes.
The lathe will answer all purposes for drilling, but small drilling
machines are now furnished at very low figures, and such a machine will
take off a great deal of duty from the lathe.
[Illustration: _Fig. 8. Pocket Screw and Wire Gage._]
As the lathe is of prime importance, never use it for drilling, if you
have a driller, as it always has enough work to do for tuning up work.
BENCH TOOLS.--Of bench tools, a 3-inch vise, various files, center
punch, two hammers, round and A-shaped peons, hack saw, compasses,
inside and outside calipers, screw driver, cold chisels, metal square,
level, straight edge, bevel square, reamers, small emery wheel and an
oil stone, make a fairly good outfit to start with, and these can be
added to from time to time.
Everything in the machine shop centers about the lathe. It is the king
of all tools. The shaper and planer may be most efficient for surfacing,
and the milling machine for making grooves and gears, or for general
cutting purposes, but the lathe possesses a range of work not possible
with either of the other tools, and for that reason should be selected
with great care.
[Illustration: _Fig. 9. Handy Bench Vise._]
SELECTING A LATHE.--The important things about a lathe are the spindle
bearings and the ways for the tool-holder. The least play in either will
ruin any work. Every other part may be defective, but with solidly
built bearing-posts and bearings, your lathe will be effective.
For this reason it will not pay to get a cheap tool. Better get a small,
6-inch approved tool of this kind, than a larger cheap article. It may
pay with other tools, but with a lathe never.
Never do grinding on a lathe. The fine emery, or grinding material, is
sure to reach the bearings; it matters not what care is exercised. There
is only one remedy for this--overhauling.
[Illustration: _Fig. 10.--Combination Square._]
COMBINATION SQUARE.--A tool of this kind is most essential, however
small. It can be used as a try-square, and has this advantage, that the
head can be made to slide along the rule and be clamped at any point. It
has a beveling and a leveling device, as well.
[Illustration: _Fig. 11.--Uses of the Combination Square._]
The combination square provides a means for doing a great variety of
work, as it combines the qualities of a rule, square, miter, depth gage,
height gage, level and center head.
[Illustration: _Fig. 12.--A Quick Adjusting Micrometer._]
The full page illustration (Fig. 11) shows some of the uses and the
particular manner of holding the tool.
MICROMETERS.--Tools of this description are made which will accurately
measure work in dimensions of ten-thousandths of an inch up to an inch.
The illustration (Fig. 12) shows an approved tool, and this is so
constructed that it can instantly be changed and set by merely pressing
the end of the plunger as shown.
[Illustration: _Fig. 13.--A Universal Bevel Protractor._]
PROTRACTORS.--As all angles are not obtainable by the square or bevel, a
protractor is a most desirable addition to the stock of tools. As one
side of the tool is flat it is convenient for laying on the paper when
drafting, as well as for use on the work.
The protractor has a graduated disk, and is adjustable so it can be
disposed at any angle.
[Illustration: _Fig. 14.--Universal Bevel Protractor, showing its
uses._]
All special tools of this kind are serviceable, and the boy should
understand their uses, even though he is not able for the time being to
acquire them. To learn how they are applied in daily use is an education
in itself.
UTILIZING BEVEL PROTRACTOR.--Examine the full-page illustration (Fig.
14), and see how the bevel protractor is utilized to measure the angles
of work, whether it is tapering heads or different kinds of nuts, or end
and side surfacing, and it will teach an important lesson.
[Illustration: _Fig. 15.--Grindstone Truing Device._]
TRUING GRINDSTONES.--Devices for truing up grindstones are now made, and
the illustration (Fig. 15) shows a very efficient machine for this
purpose. It can be applied instantly to the face of the stone, and it
works automatically, without interfering with the use of the stone.
It is frequently the case that an emery wheel will become glazed, due to
its extreme hardness. This is also caused, sometimes, by running it at
too high a speed. If the glazing continues after the speed is reduced,
it should be ground down an eighth of an inch or so. This will, usually,
remedy the defect.
[Illustration: _Fig. 16.--Set of Tools and Case._]
SETS OF TOOLS.--A cheap and convenient set of precision tools is shown
in Fig. 16, which is kept in a neat folding leather case. The set
consists of a 6-inch combination square, complete center punch, 6-inch
flexible steel rule center gage, 4-inch calipers, 4-inch outside caliper
with solid nut, 4-inch inside caliper with solid nut, and a 4-inch
divider with a solid nut.
[Illustration: _Fig. 17. The Work Bench._]
THE WORK BENCH.--This is the mechanic's fort. His capacity for work will
depend on its arrangement. To the boy this is particularly interesting,
and for his uses it should be made full three inches lower than the
standard height.
A good plan to judge of the proper height is to measure from the jaws of
the vise. The top of the jaw should be on a level with the elbows. Grasp
a file with both hands, and hold it as though in the act of filing
across the work; then measure up from the floor to the elbows, when they
are held in that position.
THE PROPER DIMENSIONS.--This plan will give you a sure means of
selecting a height that is best adapted for your work. The regulation
bench is about 38 inches high, and assuming that the vise projects up
about 4 inches more, would bring the top of the jaws about 42 to 44
inches from the floor. It is safe to fix the height of the bench at not
less than 34 inches.
This should have a drawer, preferably near the right-hand end of the
bench. The vise should be at the left side, and the bench in your front
should be free of any fixed tools.
HOW ARRANGED.--Have a rack above the bench at the rear, for the various
tools when not in use, and the rear board of the bench should be
elevated above the front planks several inches, on which the various
tools can be put, other than those which are suspended on the rack
above.
The advantage of this is, that a bench will accumulate a quantity of
material that the tools can hide in, and there is nothing more annoying
than to hunt over a lot of trash to get what is needed. It is necessary
to emphasize the necessity of always putting a tool back in its proper
place, immediately after using.