134 
MINUTES OF PROCEEDINGS OF 
which are used in subsequent turning processes. A few small holes are made 
into the mould, to allow of escape of gas when the metal is poured in through 
the runner. The shells are cast base down, as most strength is required 
there to resist the shock of the discharge. The lower part of a casting is 
always the soundest. 
When the shell is sufficiently cool it is taken from the foundry (in a truck 
which hooks on to the trunnions of the casting-box), the mould is unkeyed 
and the shell knocked out, the runner is removed and core-spindle taken out. 
9-in. and upwards are piled close together upon their base, and allowed to 
stand for about 12 hours; 8-in. and downwards have sand placed round 
them for about 12 hours. 
The shell next goes to a shed where the core is thoroughly removed, and 
the sand is scraped from the exterior with a coke scraper. The nose of the 
shell is knocked off. The shell goes to the turning-room, and is centred. 
In one lathe it has its nose cut to proper length, and turned down to 
the proper curve; the fuze-hole is bored out to correct size, tapped to 
receive the gun-metal bush,* and has a recessed groove cut at the bottom. 
The bush is next screwed in, and violently jammed home to expand it into 
the recessed groove. It is tapped with a screw-thread—G.S. gauge—and 
its end is cut off, leaving a recess * * § 2 in. deep.t The extractor holes are 
bored, the body is turned, the stud-holes are bored out and undercut. 
Steam Testing. 
Steam is admitted into the shell at a pressure of 40 lbs. to the square 
inch. This detects any porous shell, and also serves to heat the shell to the 
required extent for lacquering.J The lacquer (Spanish brown, resin, plaster 
of Paris, and turpentine) is poured in hot,§ and immediately poured out 
again. The shell is thus given a fine uniform coat of lacquer.|| 
The gun-metal studs,which are softened by annealing, are then pressed 
in. They have a concave hollow in the dower part, which causes them to 
expand into the undercut hole. The pressure has been estimated by Captain 
Sladen as equivalent to a statical pressure of about 30 tons on a 7-in. shell.** 
After pressing in the studs they are turned, and planed in another machine 
to fit the rifling. A machine with a bar which can be set so as to give the 
required angle of rifling is employed. Pinally, all the studs are filed and 
trimmed by hand, and afterwards weighed and gauged. 
Limit of weight, ± per cent. 
Gauging:—(1) thickness of sides, (2) thickness of base, limits ± *05 in., 
* Field service shells are not bushed with gun-metal. 
f The 40-pr. is not recessed, the bush is flush with the top of shell. 
J Up to 25-pr., inclusive, lacquering is done before tapping the fuze-hole, as the shell being small 
turnings can be seen and readily removed. 
§ A funnel-shaped gun-metal bush is screwed into the fuze-hole, to prevent the lacquer filling up 
the threads. It is removed after the lacquer has set. 
|| This process used to be carried out before boring the fuze-hole. The iron trimmings were 
found to adhere to the lacquer of the shell, so it was advisable to lacquer after turning. 
U Copper is used for some of the small shells. 
** Experiment has since shewn that the calculation was a good approximation j the experiment 
gave about 27 tons pressure. 
