It would be a useless repetition to enter into the details of moulding ordinary iron works; but from the horizontal position of the flasks it is necessary that the part of the work which is required to be the soundest, and most free from defects, should be placed downwards, as the metal is more condensed at the lower part, and free from the scoria or sullage which sometimes renders the upper surface very rough and full of minute holes. As the flasks almost always lie on the ground, it is also found the most convenient to retain them in contact by placing heavy weights upon them; the foundry should in consequence have an abundant supply of these.

The flasks require to be poured through a hole in the upper half, as seen at r, Fig. 169, page 259, which hole is formed by placing a wooden runner stick in the top part A, whilst it is being rammed; and a small channel is afterwards cut sideways into the mould. Sometimes two, three, or even half-a-dozen or more runners are put to one single casting, either when it requires a great weight of metal, or when it is large but slight, as in trellis-work, in which case the metal might cool before filling the mould if only introduced at one single runner.

When the runners are required to be lofty, either to supply pressure to the metal, or as a reserve to fill up the space left by its contraction in cooling, iron rings of six or eight inches diameter are piled up to the required height, to support the tube of sand contained within them. Small objects that are poured from one hole, are frequently moulded with two runners, that the metal may flow through the mould, and that there may be a sufficient supply to meet the shrinkage, and also to supply head or pressure; another advantage also results, as it assists in carrying off the scoria or sullage.

The iron-founder employs all the methods of coring explained at pages 245 to 248, and also others of an entirely different kind but little required in brass-works; namely for lateral holes in the parts of the castings buried beneath the general surface of the mould, and which are explained by the Figs. 158 to 161. Thus 158 represents the finished casting, 159 the model of the same, 160 the appearance of the bottom flask or drag when the pattern is first re-moved, and 161 the flask and cores when closed ready for pouring; the moulds are inverted, and the same letters of reference refer to similar parts of all these figures.

Figs. 158

159 d

161.

The core print a, would deliver from the sand and leave the cavity at a, Fig. 160, to be afterwards filled by the core shown black in Fig. 161, the same as formerly explained at Fig. 143, p. 245. But the core print, b, Fig. 159, (which has reference to the black stud b, Fig. 161,) would tear away the sand above it in withdrawing the pattern; therefore the print b should, like d, Fig. 159, extend to the face of the pattern, or the parting line represented by e, Fig. 161. This being the case, the pattern would leave the space denoted at d, Fig. 160; the core is put down sideways to the bottom of the recess, and extends entirely across the same; the small open space above, is made good with the general surface, as shown by the shade lines in Fig. 161, and this filling in at the same time fixes the core precisely where denoted by the print d, which latter has a mark to show to the moulder where the core is to end. The circular hole requires the core print shown at c, Fig. 159; the cores themselves are made in the core-boxes 144 and 145, before explained at page 246.

Fig. 163 represents the model and core-print, from which the finished casting shown at Fig. 162 might be made from a solid pat tern in a two-part flask; it would be inverted, and the parting would be made upon the line, x. The prints for the four holes a a, would be placed in the top flask, and those for the great apertures or panels d, would be made in a core-box of the express form, and 17 as thick as the pattern and core-print measured together. The core would be deposited edgeways into the core-print, and the upper corners of the mould would be made good, as explained in Fig. 161.

By the same method, a mortise wheel, or one with spaces around its edge, as at m m, Fig. 164, to be filled with wooden cogs, might be made with a series of core-prints, as at c, brought up flush with the parting of the mould; if every print were filled with a core such as Fig. 165, made in an appropriate core-box, the matter would be accomplished with great facility and truth.

The iron-founder makes frequent use of flasks, which divide in three or four parts; this is done in many cases simply to increase the depth of the contained space; in which case when wooden flasks were employed, they admitted of being temporarily fixed together by dogs, or large iron staples, driven a little way into the neighboring flasks, but the modern iron flasks are fixed by cotters. The following examples will show the nature of some other uses to which the flasks with several partings are applied.

Fig. 166.

Fig. 167.