Bedding-in
One process for obtaining an impression in the sand, of the lower or under side of the pattern. Simple objects may be pressed, or hammered into a suitably prepared soft bed of sand, while those of a more complex nature must have the sand tucked with the hand, or forced with small rammers into remote parts; supplementing these operations by effectual ramming with the ordinary peen and butt-rammers--which operation extends to all parts of the hole or pit in which the mould is being prepared. Should this be neglected, the inside pressure, when the mould is cast, will press the surface back into the soft parts and a swelled, uneven surface will result. This process may, in some instances, be simplified and made more effective by suitably dividing the pattern and ramming each piece separate, from the bottom upwards. Again, it may be found convenient to form some portion, if not all of the bed, by extemporized strickles and guides before lowering on the pattern for a final ramming. See RAMMING; VENTING; TUCKING; TRAMPING. Bed-fuel is the fuel resting on the sand-bed or bottom of the cupola and immediately preceding the first charge of iron, the amount of which is regulated according to the diameter of the cupola and the depth of the bottom. If coal be the fuel used, about 15 inches above the tuyeres would be sufficient for bed-fuel, and about 22 inches for coke. See CUPOLA; CHARGING THE COMMON CUPOLA.