bolts and nuts

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

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