56 



FARM MECHANICS 



way of cutting that mashes the rod the least is to be 

 preferred. The size of the rod will determine the man- 

 ner of cutting in most instances. 



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Figure 84. Taper Tap for Blacksmith's Use. 



Figure 85. Machine Bolt and Carriage Bolt. The first is used 

 against iron and the second against wood, but this rule is not arbi- 

 trary. The rounded side of the nuts are turned in against wood ; 

 the flat side against washers or heavier iron. Use square head bolts 

 if you expect to take them out after the nuts have rusted on. 



Figure 86. Plow bolts and sickle bar bolts should be kept in 

 stock. Standard sizes and shapes are made for several different 

 makes of plows and machines. 



Taps and dies are made to fit each size of rod. If the 

 thread on the bolt is cut with a solid, or round, plate 

 die, the corresponding tap is run clear through the 

 nut. In that case the nut will screw on the bolt easily, 

 possibly a little loose for some purposes. It is so in- 

 tended by the manufacturers to give the workman a 



