Canadian foundryman (1917) . ries forGeneral Information, Observations and Suggestions—Your Co-operation is Invited WHY A PATTERN IS DIVIDEDBy D. A. Sampson. IT IS very hard bo get designers andpatternmakers to divide their patternsprofitably because few of them takethe trouble to obtain the moulders view-point. A mould is made in a box calleda flask. that is split horizontally, andin which the pattern has been placed ondthe sand packed around it. Now note,to get that pattern out, the halves ofthe mould have to be lifted off the pat-tern, or the pattern has to be lifted outof the mould; there
Canadian foundryman (1917) . ries forGeneral Information, Observations and Suggestions—Your Co-operation is Invited WHY A PATTERN IS DIVIDEDBy D. A. Sampson. IT IS very hard bo get designers andpatternmakers to divide their patternsprofitably because few of them takethe trouble to obtain the moulders view-point. A mould is made in a box calleda flask. that is split horizontally, andin which the pattern has been placed ondthe sand packed around it. Now note,to get that pattern out, the halves ofthe mould have to be lifted off the pat-tern, or the pattern has to be lifted outof the mould; there is a vast difference,and on this difference hinges the reasonfor divided patterns. As an example, consider the patternin Fig. 1, which has a deep lug extendingon opposite sides of the hub, and coreprints at the ends. Assuming that thispattern were made solid, and that wecould look into the mould before the pat-tern was drawn (out), we would seesomething like Fig. 2. The parting lineis marked; it is the line between the up-. fig. l per and lower halves of the mould,known respectively as the cope andthe drag. In order to get the patternout of the mould, the cope has to belifted off the pattern, the latter remain-ing in the drag if the moulder has goodluck. The pattern has in all six verticalfaces, and the trick is to lift the cope offso that none of them knock off anysand—a practical impossibility. Therounded hubs and the tapering sides ofthe lug draw without any trouble, butthe vertical faces, even though madewith the usual draft, are sure to catchportions of sand and spoil the mould sothat patching: up is required. When it isconsidered that this cope may be a box18 or 20 inches square, and 8 or 10inches deep, and weighing up to a hun-dred pounds, the proposition of a manlifting: it 5 or 6 inches in a perfectly-straight line, never raising one cornet-ahead of another, is a formidable while he is dointr this, he cannotpossibly see underneath to gain an ideaas to how s
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