Place the drag in position and ram it up in the usual way, only using facing sand next the joint and pattern. Place six long gaggers to strengthen the sand which forms the inside of the casting. Clamp the drag to the cheek and roll them over. Test, repair, and dust parting sand on the joint. Try the cope. The bars should clear the pattern and joint by about 1 inch. Set the cope runner about 2 inches to one side of the cheek runner and set the riser in the corner opposite. Sift on facing sand and tuck well with the fingers under the crossbars. Shovel in well-cut sand and finish packing the cope. Form a pouring basin, and vent well. Lift the cope. Draw the pattern from the cheek. Join the runners on the cope joint and connect the mold with the riser. Lift the cheek and repair it. Draw the drag pattern. All of the mold surfaces should have black lead facing brushed over them with a camel's hair brush, and this facing slicked over. Cut a gate on the drag joint. Close the cheek on the drag. Close the cope on the cheek, and the mold is ready for clamping. Floor Bedding. Owing to the development of the electric crane, there is much large work now rammed in iron flasks and rolled over, which was formerly always bedded in the floor. This method is still much used in jobbing shops to avoid making a complete large flask.
The mold shown in Fig. 52 illustrates the principal operations involved. The casting is a flask section for a special steel-ingot mold, and in design is simply a heavy plate braced on one side by flanges and ribs of equal thickness. For convenience in ramming between the flanges, portions of the top plate of the pattern are left loose, as seen in Fig. 53.
Dig the pit for the mold 10 inches larger on each side than the pattern, and about 6 inches deeper. Having screened some hard cinders through a No. 2 riddle, cover the bottom of the pit with them to a depth of 3 inches. Ram these over with a butt rammer, and at one end set a piece of large gas pipe. Put a piece of waste on the top of this to prevent its getting choked with sand. Ram a 3-inch course of sand over the cinder bed and strike it off level at the depth of the pattern from the floor line. Sift facing sand over this where the pattern will rest; set the pattern, and with a sledge, seat it until it rests level. Remove the pattern and with the fingers test the firmness of packing all over the mold. Vent these faces through to the cinder bed, and cover the vent holes with a 1/2-inch course of facing sand. Now replace the pattern, and bed it home by a few more blows of the sledge. The top of the pattern should now be level and flush with the floor line. Seat the runner sticks, and,to prevent the sand on the bottom of the runners from cutting, drive 10-penny nails about 3/4 inch apart into this surface until the heads are flush. Ram the outside of the mold the same as if in a flask, and strike a joint on top. Ram green sand between the inside webs of the pattern, and strike off at the proper height with a short stick a, Fig. 54. Drive long rods 3 inches apart into these piers to pass through to solid sand below the cinder bed.
Vent all around the pattern, outside and inside, through to the cinder bed. On top of the inside piers cover these vent holes with facing sand, ram, and slick to finish; then cover with the loose pieces of the pattern.
Try the cope and stake it in place; set the risers and vent the plugs. Ram the cope, slicking off level for about 2 inches around the top of the risers, to receive a small iron cover.
Fig. 53. Bedded-ln Work.
Lift the cope, repair, and face with graphite. Draw the pattern with the crane and finish the mold. Connect the outer vent holes by a channel with the vent plug. From the end of each core print bbbb, Fig. 53, vent through to the cinder bed, and set the cores. Close the cope. Set the runner box against the side of the cope and build a pouring basin with its bottom level with the top of the risers.
In weighting, great care must be exercised not to strain the cope. Place blocking upon the top ends of cope. Across these lay iron beams which will be stiff enough to support the load, and pile weights on these, as shown in Fig. 52. Now wedge under the beams to the crossbars of the cope at necessary points.
Fig. 55. Leveling a Bed for Open Sand Work.
There is a large class of foundry rigging, such as loam plates, crossbars, and sides to iron flasks, which may be cast in open molds. As there is no head of metal, the beds must be rammed only hard enough to support the actual weight of the metal, or it will boil. To insure uniform thickness in the casting, the bed must be absolutely level.
Drive four stakes acuta, as shown in Fig. 55, and rest the guide boards AA on the top of these. By using a spirit level bb, make these level, and bring them to the same height by testing with the straightedge S.
The space between the guide boards AA should be filled with well-cut sand even with their tops dd. Sift sand over the entire surface. Strike this sand off 3/4 inch higher than the guides, by placing a gagger under each end of the straightedge, as it is drawn over them. Tamp this extra sand to a level with the guides by rapping it down with the edge of the cross-straightedge, and the bed will be as shown in Fig. 56. We can now proceed to build up to a segment of pattern, or with a sledge drive a pattern into this surface.
The pouring basin should drain itself at the level of the top of mold, and an overflow may be cut on one edge to drain the casting to any desired thickness.