Mechanical Drawing Self-Taught

CHAPTER II.. The Preparation and Use of the Instruments.

THE PREPARATION AND USE OF THE INSTRUMENTS.

Preparing the lining pen for use 34

The shapes of the lining pen points 35

Oil stoning pen points 36

Preparing the circle pen for use 38

The shape for circle pen points 38

Shaping circle pens for very small circles 39

A form of pen point recently introduced; forming the pen point 39

The method of oil-stoning circle pen points 40

The needle point and pen point 42

How to use the circle pen 43

German instrument to avoid slipping of a needle point 44

How to use the lining pen 45

Applying the ink to the bow-pen 46

Using a straight line or lining pen with a T square 47

CHAPTER III.. Lines and Curves.

LINES AND CURVES.

Explanation of simple geometrical terms; radius; explanation of conventional dotted lines 48

A line at a right angle to another; a point; parallel lines 49

A line produced; a line bisected; a line bounding a circle; an arc of a circle; segments of a circle; the chord of an arc; a quadrant of a circle 50

A sector of a circle; a line tangent to a circle; a semicircle; centre of a circle; axis of a cylinder; to draw a circle that shall pass through three given points 51

To find the centre from which an arc of a circle has been struck; the degrees of a circle 52

The protractor 53

To find the angle of one line to another 54

To find the angles of three lines one to the other 55

Acute angles and obtuse angles 57

Triangles; right angle triangle; obtuse angle triangle; equilateral triangle; isosceles triangle 58

Scalene triangle; a quadrangle; quadrilateral or tetragon 59

Rhomboid; trapezoid; trapezium 60

The construction of polygons 61

The names of regular polygons 62

The angles of regular polygons; the ellipse 63

Form of a true ellipse 69

The use of a trammel for drawing an ellipse 72

To draw a parabola mechanically 73

To draw a parabola by lines 74

To draw a heart cam 75

CHAPTER IV.. Shadow Lines and Line-Shading.

SHADOW LINES AND LINE-SHADING.

Section lining or cross-hatching 77

To represent cylindrical pieces one within the other; to represent a number of pieces one within the other 78

To represent pieces put together and having slots or keyways through them. 79

Effects of shading or cross-hatching 80

Lines in sectional shading or cross-hatching made to denote the material of which the piece is composed--lead, wood, steel, brass, wrought iron, cast iron 81

Line-shading 82

The shade line to indicate the shape of piece; representation of a washer 83

A key drawn with a shade line; shade line applied to a nut; a German pen regulated to draw lines of various breadths 84

Example of line-shading in perspective drawing, shown in a pipe threading stock and die 85

A cylindrical pin line-shaded; two cylindrical pieces that join each other; a lathe centre; a piece having a curved outline 86

Line-shading applied to a ball or sphere; applied to a pin in a socket shown in section 87

A piece of tube, where the thickness of the tube is shown; where the hollow or hole is seen, the piece shown in section; where the body is bell-mouthed and the hollow curve shown by shading 88

Example of line-shading to denote the relative distances of various surfaces from the eye 89

Line-shading to denote that the piece represented is of wood; shade-lines being regular or irregular 90

CHAPTER V.. Marking Dimensions.

MARKING DIMENSIONS.

Examples in marking dimensions 91

CHAPTER VI.

THE ARRANGEMENT OF DIFFERENT VIEWS.

The different views of a mechanical drawing; elevation; plan; general view; a figure to represent a solid cylinder 94

To represent the different sides of a cube; the use of a cross to denote a square 95

A triangular piece requires two or three views 96

To represent a ring having hexagon cross section; examples; a rectangular piece in two views 98

The position of the piece when in its place determines the name of the view in the drawing 103

View of a lever 105

Best method of projecting one view from another; the two systems of different views of a piece 106

CHAPTER VII.. Examples in Bolts, Nuts and Polygons.

EXAMPLES IN BOLTS, NUTS AND POLYGONS.

To represent the thread of a small screw 112

A bolt with a hexagon head 113

United States standard sizes for forged or unfinished bolts and nuts 116

The basis of the Franklin Institute or United States standard for bolts and nuts; hexagonal or hexagon heads of bolts 118

Comparison of hexagon and square heads of bolts; chamfers 120

Without chamfer; best plan for view of both square and hexagon heads 123

Drawing different views of hexagon heads 125

To draw a square-headed bolt; to draw the end view of a hexagon head 125

Use of the triangle to divide circles 129

Scales giving the length of the sides of polygons 135

To find what a square body which measures one inch on each side measures across the corners; to find what diameter a cylindrical piece of wood must be turned to which is to be squared, and each side of which square must measure an inch 136

To find a radius across corners of a hexagon or a six sided figure, the length of a side being an inch 138

To draw a stud 142

To pencil in a cap nut; pencilling for a link having the hubs on one side only 145

Link with hubs on both sides; pencil lines for a double eye or a knuckle joint 146

Double eye or knuckle joint with an offset; a connecting rod end 147

A rod end with a round stem 148

A bolt with a square under the head 149

Example in which the corner where the round stem meets the square under the head is sharp; a centre punch giving an example in which the flat sides gradually run out upon a circle, the edges forming curves 150

CHAPTER VIII.. Screw Threads and Spirals.

SCREW THREADS AND SPIRALS.

Screw threads for small bolts with the angles of the thread drawn in, and the method of doing this 152

A double thread; a round top and bottom thread such as the Whitworth thread; a left hand thread; to draw screw threads of a large diameter 156

Drawing the curves for screw threads 157

To draw the United States standard thread 160

To draw a square thread 162

Form of template for drawing the curves of threads 165

To show the thread depth in a top or end view of a nut; to draw a spiral spring 166

To obtain an accurate division of the lines that divide the pitch 167

CHAPTER IX.. Examples for Practice.

EXAMPLES FOR PRACTICE.

A locomotive spring; a stuffing box and gland; working drawings of a coupling rod; dimensions and directions marked; a connecting rod drawn and put together as it would be for the lathe, vise, or erecting shop 169

Drawings for the blacksmith 172

A locomotive frame 174

Reducing scales 175

Making a drawing to scale 177

CHAPTER X.. Projections.

PROJECTIONS.

A spiral wound around a cylinder whose end is cut off at an angle 178

A cylindrical body joining another at a right-angle; a Tee for example 180

Other examples of Tees 181

Example of a cylinder intersecting a cone 186

A cylindrical body whose top face if viewed from one point would appear as a straight line, or from another a circle 188

CHAPTER XI.. Drawing Gear Wheels.

DRAWING GEAR WHEELS.

Names of the curves and lines of gear teeth 193

How to draw spur wheel teeth 194

Professor Willis' scale of tooth proportions 195

The application of the scale 197

How to find the curve for the tooth face 198

To trace hypocycloides for the flanks of teeth 200

Sectional view of a section of a wheel for showing the dimensions through the arms and hub 202

To draw an edge view of a wheel; rules for drawing the teeth of wheels; bevel gear wheels 203

The construction to find the curves 204

To draw the arcs for the teeth 205

To draw the pitch circle of the inner and small end of the pinion teeth 206

One-half of a bevel gear and an edge view projected from the same 207

A pair of bevel wheels shown in section; drawing of a part of an Ames lathe feed motion; small bevel gears 208

Example in which part of the gear is shown with teeth in, and the remainder illustrated by circles; drawings of part of the feed motion of a Niles horizontal tool work boring mill 209

Three bevel gears, one of which is line-shaded; the construction of oval gearing; Professor Rankine's process for rectifying and subdividing circular arcs 210

Various examples of laying out gear wheels 214

CHAPTER XII.. Plotting Mechanical Motions.

PLOTTING MECHANICAL MOTIONS.

To find how much motion an eccentric will give to its rod 223

To find how much a given amount of motion of a long arm will move the short arm of a lever 224

Example of the end of a lever acting directly on a shoe; a short arm having a roller acting upon a larger roller 225

Continue reading Mechanical Drawing Self-Taught free in the Wunder reader →