Journal of Agriculture, Victoria. [io Feb., 1912. 



To make a solid mild steel ring of the same dimensions, a piece of 

 i\ in. s(]uare steel would be necessary. In order to make it the right 

 size, it is requisite that the quantity of metal be calculated. This may 

 be done as follows: — Ascertain the cubical contents of the ring and divide 

 the product bv the cross sectional area of the bar it is to be made from. 

 If the required internal diameter be 5 in., then the solidity of the ring 

 will be equal tn the product of the sum and difference of the internal and 

 external diameters multiplied by the depth of the ring and 11-14 or .7854. 

 This product, divided by i^ squared, will be the theoretical length re- 

 quired. But, in forging work, this quantity is not sufficient, because 

 there is always a loss of material by heat and compression in hammering, 

 foT which allowance must be made. This allowance is variable, according 

 to number of heatings necessary ; but, in most cases, an addition of 5 

 per cent, will suffice for mild steel, whilst 10 per cent, is requisite for 

 iron forgings. On working out the equation, the length will be found 

 to be i\ in. nearly. When the piece is cut off the bar, two marks should 

 be made on it. each one being -| in. from the ends. 

 Heat to bright red for the entire 



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49- 



a. End scarfed, 

 corner bent, 

 for welding. 



OBLONG FRAME. 



h. First corner beut. c. Second 



d. Third corner bent, and ready 



e. Finished frame. 



length, and then split with the hot 

 chisel, care being taken to make 

 the cut through the centre of the 

 bar lengthwise, and between the 

 two marks before mentioned, so as 

 to prevent having a thick and thir. 

 side. In cutting anything of this 

 description, the chisel should never 

 be driven right through the piece 

 from one side. The cut should 

 be made about half-way through 

 and then treated the same from 

 the opposite side. After splitting, 

 it is opened out to a rough 

 shaped ring by up-ending it on the 

 anvil whilst the middle is hot, 

 and l)v striking the top. By heat- 

 ing and heating out on the beak of 

 the anvil, a correct circle will be formed. 



The bands 'on the nave of a wheel or the tyre are made by bending 

 and welding. They are afterwards " shrunk on. " The iron for nave 

 bands is now rolled thinner on one edge than the other, sO' that when the 

 band is made the inside diameter will be larger on one side than the 

 other, which will enable it to be driven on rightly. At the sanie time, 

 there are many still made from the ordinary flat bars and the taper is 

 given to the band in forging. 



When a band is tO; be shrunk on, it shnuld be forged slightly smaller 

 than the external diameter of the wheel or whatever it is intended for. 

 If a band has to be shrunk on to wood, it would be made smaller than 

 if it had to be shrunk on tO' iron, on account of wood being more com 

 pressible than iron, and also for the reason that wood becomes charred with 

 the heat from the iron, and is thereby reduced in size. 



In agricultural machinery, there are a number of parts made of cast 

 iron, such as the cog and pulley, which are connected with its mechanism. 

 Sometimes, as the result of accident, thev are broken, and there 



