. American foundry practice . lper is turning the barrel. The barrel should neverbe turned fast. When turnedonce around, make the balanceof the loam thinner and goaround again. As the circle iscompleted, jjull back the boardendwise while the barrel is yetin motion. By doing this nomark will be left on the core. If you can finish the core intwo revolutions, it will besmoother than if it takes four orfive revolutions to do it. Ifthere should be any rough i)laceson the surface, instead of usinga trowel, use a smooth, hard-wood block to smooth them with,dampening them with water andloam, and rubbi
. American foundry practice . lper is turning the barrel. The barrel should neverbe turned fast. When turnedonce around, make the balanceof the loam thinner and goaround again. As the circle iscompleted, jjull back the boardendwise while the barrel is yetin motion. By doing this nomark will be left on the core. If you can finish the core intwo revolutions, it will besmoother than if it takes four orfive revolutions to do it. Ifthere should be any rough i)laceson the surface, instead of usinga trowel, use a smooth, hard-wood block to smooth them with,dampening them with water andloam, and rubbing with the blocktill smooth and level. If the core is large in diameter,it is best to keep the barrel turn-ing slowly until the loam is setenough so it will not sag. Ifthe barrel is stopped when theboard is taken away, the core isapt to be out of round. In turn-ing the barrel, never turn upagainst the sharp edge of thesweep, but towards the beveled portion, as shown. Thethicker the casting, the more body or thickness of loam. 3IAKIXG HAY ROPE LOAM CORES. 20? there should be over the ropes, esi^ecially if the iron ispoured hot. AVlien there is not enough loam over the ropes,the hot iron heats through the loam and burns the ropewhile tlie iron is yet liquid, and the iron will strain into thesoft open places, and the casting will have lumps on it. To make a cas^ting one inch thick, the core barrel shouldbe about three inches smaller than the finished size of thecore. This will allow It^ inches on each side of the barrelfor rope and loam. The size of rope should be about J ofan inch, which would leave J of an inch for loam, f of aninch of which should be left for the finishing coat. Forcastings about 2 inches thick, 1 inch thickness of loamwill be safe. During the war a firm in this country cast heavy cannonsby coring them out, to save some of the boriug and make astronger cannon. The cores were swept up on a barrel, and,instead of using hay ro])e, they used ropes made of
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