52 Journal of Agriculture, Victoria. [lo Jan., 1912- 



mount slightly smaller than the wood ; and, by making the iron red hot 

 and quickly driving on and cooling out before the iron burns too deep, 

 the contraction of the iron will hold it tight, just as a tvre is held on to^ 

 a wheel. 



Forging a Bolt. 



The majority of bolts are made by machinery ; but, at the same time, 

 blacksmiths are continually being called upon to make them for special 

 purposes and where it is not convenient to buy them. Machine made bolts 

 are short, ra;rely exceeding 10 in. long; so that when a longer bolt is re- 

 quired it is either made outright by the smith or else a shorter one is 

 lengthened. Screwed ends, i.e., plain circular pieces of iron cut off in 

 9 in. or 10 in. lengths, are screwed at one end, and a nut fitted to them 

 at the bolt factories and sold cheaply bv most ironmongers. They are 

 very convenient and save a great deal of hard work in screwing, par- 

 ticularly in large bolts. 



If a long boit, say 2 ft., be required, a head would be made on a 

 piece of iron and a screwed end welded on to the other end. 



A bolt head is made by wrapping a piece of square or flat iron around 

 the end of the required sized round iron ; and, after raising to a welding 

 heat, forging the head to shape. 



In order to do this in an inteljigient and systematic manner, several 

 things require to be taken into consideration. In the first place, it will 

 be understood that in the United Kingdom bolt-heads and nuts are made 

 to fixed measurements, known as Whitworth's standard, so that a bolt 

 made in one shop will fit a nut made in another ; also, that a spanner may 

 be made to suit the nuts of all bolts of a given size. The size of a bolt 

 is known by the diameter of iron in its circular part. 



The farmer who has an American as well as an Australian made 

 machine has no doubt found out that a nut from one will not fit a bolt 

 from the other. This is on account of the United States engineers having 

 adopted a standard known as the Sellars, which is slightly different to the 

 English. But, even in American machines made by different makers, the 

 nuts are in many instances not interchangeable. 



The importers of agtt'icultural machinery, besides selling the com- 

 pleted machine, also sell duplicate parts, and they are particularly careful 

 that the duplicates of their machines will not be exactly suitable for 

 others. Consequently, the user of the machine is practically compelled to 

 buy his renewals from the agent from whom he bought his machine. 

 Whilst one cannot blame the manufacturer for protecting his own interests, 

 the practice is at times aggravating to the farmer. When a nut drops off 

 a screwed end, he finds that, although he has some of the same sized nuts 

 on hand, the threads are differently cut, and so cannot be made use of, 

 necessitating a journey of often many miles for the proper article. 



The Whitworth standard of sizes for bolt heads, nuts, and the width 

 of spanner jaws, is found by taking the diameter of the iron in the body 

 of the bolt as the unit, and multiplying that diameter by # and adding 

 ^ in. to the product. The depth of nut equals the diameter of the bolt, 

 whilst the depth of head is f that of the nut, but in ordinary practice, is 

 mad^ the same. When making a bolt, it would be well to bear this in 

 mind, for it is far more satisfying and no more difficult to make the head 

 right than wrong. 



