46 



ELEMENTARY WOODWORKING 



needed for circles and arcs of circles. Each triangle con- 

 tains one right angle, the one on the left being known 

 as a thirty-sixty triangle because the two remaining 

 angles are thirty degrees and sixty degrees respectively. 

 The one on the right is called a forty-five-degree triangle 

 because it has two forty-five-degree angles. 



The position of T square and triangle when drawing 

 vertical lines is that shown in the sketch, the line being 



drawn from the T square 

 upward. Horizontal 

 lines are drawn from left 

 to right. 



The rule used in me- 

 chanical drawing is 

 called a scale, and should 

 not be used for draw- 

 Its purpose 



Fig. 61. 



The Triangles used in Mechan- 

 ical Drawing 



ing lines. 



In making a drawing the first step is to determine 

 the spacing. The size of the paper may be measured, 

 the number of views are known, and also the size of 

 each. The views should be so arranged that the spaces 

 between will be in good proportion. It is a good plan 

 to make first a free-hand sketch, putting on dimen- 

 sions and figuring the spaces before beginning actual 

 work on the mechanical drawing. Fig. 62 at a shows 



