In molding the above cylinder it is not necessary that the pattern should be parted - made in two halves - as shown in Fig. 106. Patterns for small work, and even for large castings, are often made in one piece, as shown in Fig. 111. To mold this solid pattern it is placed on the molding board with sufficient sand to keep it from rolling, and the drag is inverted over it as before. When the drag has been rammed up, it is turned over, and will then present the appearance shown in Fig. 112, the entire pattern being embedded in the sand. The sand is now cut away and removed, as shown in Fig. 113, down to the center line of the pattern. The cut sand is smoothed; and, after dry parting sand has been applied to the surface of the wet sand, the cope is placed in position and rammed up as usual. Upon the cope being removed, the sand will part along the lines de and cd, leaving one-half of the entire pattern exposed. The pattern can now be lifted out, the core placed in position, and the cope returned to its place on the drag, when it is ready for the pouring, as in Fig. 110.
Fig. 111. Solid Pattern for Cylinder.
Fig. 113. Coped-Out Mold for Solid Patterus.
Another example of a one-piece pattern is the small brass hand wheel shown in Fig. 114. The pattern for this wheel is placed on the molding board, and the drag inverted over it and rammed up. After the drag has been turned over, the sand is cut away and removed, not only down to the center of the rim, but also to the center line of the four arms, as shown by the dotted lines in Fig. 115. All cut surfaces of the sand are smoothed, parting sand is sprinkled over the parting thus made, and the cope is placed in position and rammed up. When the cope is lifted off, the sand will part half way down on the arms and rim, allowing the pattern to be taken out easily.
Fig. 114. Hand Wheel.
Still another example in which a single-piece pattern can be used, is shown in the journal-box cap illustrated in Fig. 116. A cross-section of the pattern through two of the bolt-hole core prints is shown in Fig. 117. The pattern is placed on the molding board in the inverted drag, and is rammed up as usual. When the drag is turned over, the position of the pattern in the sand is as shown in cross-section in Fig. 118. The sand that may have entered the curve cde is lifted out, and the necessary draft is given to the sand at the two ends of the opening cde, as shown at a, Fig. 119. The cope is next placed in position, and when this has been rammed up and lifted off, the sand lying in the curve cde will be lifted with it. The pattern is now removed, the bolt-hole cores are placed in position, and the cope is returned to its place on the drag.
Fig. 117. Cross-Section of Cap Pattern.
In this case the core prints should be in length at least twice the thickness of the metal through which the hole is to be cast, and the length of the cores will be equal to the thickness of the metal plus the length of the prints.