118 ABC OF THE STEEL SQUARE 



that will enclose the section of rail; the corners 

 will then be left complete. 



The following method shows the least thick- 

 ness the rail can be cut out of, and also gives 

 width of face molds on the joint. Set the bevel 

 to the bed block as shown at Fig. 80, and apply 

 at the side of the block. Draw a section of rail 

 level; apply the bevel again, touching the bot- 

 tom corner of the section. The distance between 



Fig. 80. Fig. 81. 



the marks is the thickness, a plumb line marked 

 on shows the width of the face mold on the bevel 

 line. Where the pitches are different the fore- 

 going method has to be applied to each side of 

 the bed block. 



The bevels may be also obtained by the steel 

 square. Take the width of prism face ( shown 



