18-POUNDER SHELLS.

Auckland Star, Volume XLVII, Issue 30, 4 February 1916, Page 3

18-POUNDER SHELLS.

1 CAN BE MADS IN NEW J ZEALAND. I A SUCCESSFUL DEMONSTRATION. IEXrLATXED BY HOX. A. M. MYERS. The Minister of Munitions, who ie in Auckland to-day, says that it has been! J conclusively shown that shell casca can! jbe made in New Zealand. In fact, a) very succssful case has been manufac-1 i twred as a sample. The Hon. Mr. 'Myers | explained to a pressman that through I ■ the kindness of the Australian authori-l > ties, he had been supplied with the i formulae, specifications, plans, etc, I which were necessary for the manufac-1 ture of the IS-pounder high explosive | I shell of which such enormoue quantities i I are required in the present war. In I or<lr- to make a demonstration a small j quantity of steel had been procured | from Broken Hill. I Profes.-or R. J. Scott, of Christehurehv chairman of the committee, offered to' undertake to turn out an experimental! ; batch of the shells, and for this pur-1 pose Mr. E. H. Hiley, G-eneral Manager | 1 of Railways, placed at his disposal the! I services of Mr. Jackson, chief mechanical | engineer, and the staff and machinery of j ■ the Addington Railway Workshops. It j is interesting now to learn that 18-pound • high explosive shell bodies true to War i OfKcc specifications have been turned out, the finished article, it is stated, presenting a decidedly workmanlike appearance, and reflecting great creuit on those ' concerned with its manufacture. i The whole of the formation of the ': shell is effected by machining, no forgi ing or pressing or heat treatment being I now required. Some idea of the work I involved may be gathered from the fol-1 lowing short description of the process) of manufacture from the arrival of the j steel at the works to the finished ' '■ article. I I Test specimens are cut from the steel! ,! bars, and on these passing somewhat' ,'exacting physical tests, the bars are: ! straightened and cut up into lengths,; ■?ach of which will make a single shell.; 'These blanks are drilled to form the | i cavity for the explosive, the cavity being j ; subsequently carefully bored and then - . I exposed to a sand blast, which gives the 'exceedingly smooth finish necessary for; : nafe handling, whore high explosive | . charges are used. As a further protec-' : tion, the ini-crior of the shell is var-: i nished and the ?urface baked. The mouth of the cavity is screwed to take I the standard fuse, all measurements of! : this pirt bt'.ng made to the thousandth I part of an inch and the extreme per-| I raissibie variation in size being .006. It--lin therefore quite evident that such | r Hor!; van be accomplished only with the I i assistances of gauges and the most | p.rcurate of tools, and to enable the] '■ above-mentioned batch of shells to be' i made s,oine sixty gauges had first to bu ■. i manufactured by the Railway Depart-; .'rneiit. each in al! portions accurate to j j the thousandth part of an inch. | : The body of the shell is turned and ' , J the newe ((round, the permissible variation in the diameter being one hun- ' I dredth part of an inch, bat accuracy '' comparaible with that at the fuse screw jis r«|uir«l in the copper driving band, ' which serves the double, purpose of a 1 j jraa -check and means :of ""rotating the ■ projectile by being forced into the rifling L of the gun. The formation of the groove : ior taking this band is a very "nice" operation. It has to be undercut to an i amount coin-pa ruble vrilh the size of a ; pin's head, and also have formed in it ; a pair of waved ribs, the function of | which is to ensure the rotation of the ■ ; projectile. The band itself is made from : copper tubing of a eize which will juet slip ; !! on to the finished projectile. The neces- ! jsary supply of copper tubing was pro- | cured from the Victorian State Munitions Committee, who had imported a large quantity eirppliod te War Office specification by the Broughton Copper Company. The band is compressed into its groove by means of ebc radical I hydraulic presses, which simultaneously force steel noses against it, and is after,■wards turned to correct profile. The base of the shell is then recessed and a base plate of 6teel, tbc grain of which is transverse to that of the body of the ehell, is screwed and cemented: into it. This is a precaution against i ■ the chance ignition of the bursting i charge by a flash through an undetected j flaw in the base of tbe shell. "Of course it must be remembered," said Mr. Myers to a reporter, "that if we are to proceed vigorously with the manufacture of large quantities of these shells—and to be of any real eerviee this would have to be done—the Railway Department would necessarily J have to set aside a large proportion of I ite important work of making carriagea and maintaining tbe present rolling stock, wliile if the work were undertaken by outside firms the assembling of their plant in central localities would have the effect of interfering to a large extent with the making of freezing ■works machinery and dairying machinery . which are so necessary for the carrying on of our important industries. It will ho seen, therefore, that the problem is a very -weighty one, and will require I most careful consideration." i The Minister will place the matter ■ before Cabinet, who will now consider the whole question.