MAKING BIG GUNS

Poverty Bay Herald, Volume LX, Issue 18179, 29 August 1933, Page 8

MAKING BIG GUNS

OPERATIONS DESCRIBED 90 MILES OF WIRE RIBBON The manufacture of naval and field guns was described to Gisborne Rotarians at Monday’s luncheon by Mr, H. G. Somervell, of Wellington, in an address on Woolwich Arsenal. He said that SO miles of steel wire ribbon were used in the manufacture of a 15in. naval gun. “A isin. naval gun commences with a huge billet of steel sft. in diameter, and 12ft. long. A hole 12in. in-diame-ter is bored right through the centre. This operation is performed' by the trepanning, tlie. effect of which is that steel lOin. in diameter the full length of the billet is removed. The billet of steel with the 12in. bole is heated to a red beat and under a hydraulic press hammer is pressed out to a length of 60ft-. and about 18in. in diameter, the inside bore still remaining at I2in. diameter at the completion of the operation. This inner tube in its rough is placed in quo of the leviathan lathes and turned to size..

“Few would credit the fact that there are SO miles of steel wire ribbon under the burnished surface, of a 15in. gun. This steel wire ribbon is slightly under a quarter of an inch wide and 3.64 thick and is wound on the inner tubes from a huge, drum at a tension strain of 40 tons. So tightly is the wire wound that the bore of the gun actually contracts to a smaller size after the wiring process is completed. This difference in size is called ‘compression’, a certain amount of which is essential to safety and proves the workmanship of the job. Wire inefficiently wound would be the cause of a gun bursting, and meticulous j cafe is therefore taken to obtain the, highest efficiency- in workmanship. “It might also surprise many to know that very few inner tubes ov' barrels of long naval or field guns can be bored exactly straight. There is usually' a beiid in the bore. The gun sigbter possesses instruments for detecting the side that the bend is on and the gun sight is fitted to cause the shot to go high, not round the corner or downwards. “barge guns are made in pieces and are not the solid billet of steel they at first sight appear to be. The reductions. in outside diameters from breech to muzzle are merely what are known as jackets which are first heated and then shrunk on to the 1 next smaller diameter, which usually has been preyously wired. The last operation on the gun is the rifling, or grooves cut spirally in the barrel to give the projectile a spinning motion when travelling through space, ensuring greater accuracy’ in ’shooting. A 15in. gun is required to fire' a com- 1 paratively small number of shots when the inner tube requires renewing, although our ships bombarding the Dardanelles exceeded f.lie limit many times over. When a large gnu requires a new inner tube or barrel, it is placed in a vertical' position inside a huge furnace, unslmmk ! and taken to pieces, a new inner tube is refitted, the gun re-wound and re-rifled, and ft is once more ready for action.”