Practical Iron Founding

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ... laid on a joint board, and the drag or top part placed around the pattern. There is nothing about the ramming of this that calls for any special comment. The sand is rammed hard in detail and vented, all its weak corners and angles are well strengthened with nails and rods, and the mass of overlying sand is properly liftered. Then the drag is turned over, the other half pattern laid on, and the top rammed, the flasks parted, the mould cleaned, the joints finned, and the boxes run into the stove to dry. But the real work--that which presents difficulty, or at least that which demands. 2 especial care--has yet to be done, and this will now be illustrated in detail: The two great requisites in cylinder work, after the usual and ordinary precautions common to all moulds, are the proper venting of the cores, the proper securing of the same, and the making of safe and sufficient provision for carrying off the air away from the mould. The making of the cores is accomplished precisely on the same lines as any ordinary dried cores, but since some of them are flimsy, rather more caution has to be exercised in their case. Taking the port cores first, there are two usual modes of venting--one with rods, the other with strings, --each of which is practised indifferently, the latter being most suitable for the smallest cores of all. For the smallest curved passage cores, fine string soaked in tallow may be used, and when the cores are dried, the tallow melting away, leaves the string slack. When strings are used for cores of moderate size they are either drawn out while the core is green, or after it has been dried. When drawn out while green there is a tendency of the string to cut through the cores at the corners. But if rods are rammed up crosswise, as shown at a, a, ..