2i8 Journal of Agriculture, Victoria. [lo April, 1912- 



For an iron spanner (best made as shown at D and E) take a square- 

 bar equal in size to the diameter of bolt it is intended for ; cut off a piece 

 long enough to make the handle, upset and lap-scarf it, and allow the 

 point of scarf to spread out as shown. To make the jaw, heat and upset 

 the bar at the place where the weld is to be, then bend and scarf with 

 the ball end of the hand hammer. After welding, forge to shape by cutting 

 off the corners to dotted line and finish. 



The following proportions of spanners will no doubt be found useful. 



Taking the breadth of the nut as i, then the outer diameter of jaw will 

 be 2 ; thickness of jaw fths. for steel, and fths for iron; length of handle- 

 15 ; greatest breadth of handle i ; least breadth of handle, g. 



Working and Tempering Stlel. 



It may be considered an accomplishment to know sufficient about the 

 nature of steel, and the manner in which it is manipulated at the forge, 

 to be able to make a useful tool. It certainly should be eminently useful 

 to the farmer, removed as he is, in many cases, by miles from a black- 

 smith's shop. Proficiency in the art of tool-making can only be acquired 

 by long practice, close observation, and extreme care. 



Whilst the farmer does not require to enter into all the intricate detaiU- 

 of tool-making, or study all the phenomena connected with steel, yet if he 

 is desirous of making or repairing a tool he wants to understand more about 

 it than could be learned by simply watching some one else do the work. 

 He wants to know something of the causes of failure, and of the effect that 

 heat has upon the metal, etc. By carefully following the directions given 

 in this article he should be able to meet with a fair measure of success at 

 first, and with further practice there is no reason why he should not becom.e 

 quite an expert. 



Steel is produced by mechanical means, the process chiefly consisting of 

 adding a small percentage of carbon to wrought iron. The effect of the 

 combination is that the character of the iron is altered to such an extent 

 that it almost appears to be a different metal. The structure has been 

 altered from fibrous to granulur j the hardness intensified ; the weight 

 increased, and the property of welding so affected that it becomes extremely 

 difficult and in some cases impossible of accomplishment. When steel is 

 heated to redness and suddenly cooled it becomes very hard and brittle, 

 and it is this property which makes it the most useful of all metals. It can 

 be made to cut glass ; it can be rendered so soft that it may be cut by 

 another piece of steel such as the blade of a pocket knife j it can be forged' 

 and bent into any conceivable shape. It can be made so elastic that thou- 

 sands of oscillations will not alter its shape. (For example take a watch 

 spring, which will remain visibly perfect for years). It can also be made- 

 of any degree of hardness between the two extremes, and the process by 

 which this is done is called temfering. 



Tempering by which elasticity is produced, is effected by reducing some 

 of the hardness given to steel by heating and quickly cooling it. The. 

 degree of hardness of a tool varies : firstly, by the hardness of the material 

 to be cut and, secondly, by the manner in which it is to be cut ; for instance 

 if the work is to be performed by means of a blow then the tool needs to be 

 made as elastic as possible and at the same time retain sufficient hardness 

 to maintain a cutting edge ; but if the tool be required to work in a lathe 

 where the pressure is fairly constant then it may be made much harder. 



A piece of steel that has been heated to redness and cooled out will if 

 polished be of a silvery whiteness, and if slowly reheated changes in the- 



