ABC OF THE STEEL SQUARE 11 



To insure good results, it is necessary to be 

 careful in the selection of the tool. The blade 

 of the square should be 24 inches long, and 

 two inches wide, and the tongue from 14 to 18 

 inches long and 1% inches wide. The tongue 

 should be exactly at right angles with the blade, 

 or in other words the "square" should be per- 

 fectly square. 



To test this question, get a board, about 12 

 or 14 inches wide, and four feet long, dress it 

 on one side, and true up one edge as near 

 straight as it is possible to make it. Lay the 

 board on the bench, with the dressed side up, 

 and the trued edge towards you, then apply the 

 square, with the blade to the left, and mark 

 across the prepared board with a penknife blade, 

 pressing close against the edge of the tongue; 

 this process done to your satisfaction, reverse the 

 square, and move it until the tongue is close up 

 to the knife mark ; if you find that the edge of 

 the tongue and mark coincide, it is proof that 

 the tool is correct enough for your purposes. 

 Later on, I will show by diagram how this test 

 is performed. 



This, of course, relates to the outside edge of 

 the blade, and the outside edge of the tongue. 

 If these edges should not be straight, or should 

 not prove perfectly true, they should be filed 



