F. W. PUTNAM

Fig. 61 shows the castings and Fig. 62 the pattern for a small jack requiring a balanced horizontal core. A split pattern is used, and is turned in the same manner as the pattern for the recessed cylinder previously described. It will not be necessary to go into a detailed account of this pattern, and I shall confine myself to a few sim-pie directions which may aid the amateur in easily constructing the pattern.

Be very certain that the two blocks which are to form the pattern are planed to a smooth, even surface, so that when they are dowelled and clamped together there will be a perfect joint formed. Care should be taken in locating the centers for the dowel holes, as well as in seeing that the holes are not bored too deep into the second block. That block, when ready for turning, should be very carefully centered in the lathe so that the pattern when spread apart will have both faces equal. The core-box for this pattern is shown in the isometric drawing, Fig. 63. Six blocks are required to form this core-box, as can be readily seen by reference to the figure. A and F are simply the end pieces, and are glued and nailed to pieces B and E. The pieces B, C, and Eare to be cut out and finished with a gouge, the same as for the core-box for the recessed cylinder previously described. The piece D is 1/8 in. thick, and can be readily brought to almost the required shape with a sharp knife, the surface being finally finished with file and sand-paper. When the six pieces are to be fastened together, see that the centers of each and of the blocks come in one straight line. If this not done the core made from the core-box will be very likely to leave an uneven center in the casting.

If we look at Fig. 61 we will notice that the hole does not run way through the casting, it being intended that the top hole shall be drilled out after the casting is made. This leaves one end of the casting solid and so a balanced core is necessary.

No absolute rule can be given for the relation of length to diameter in the case of the projecting core print. It will be found that the dimensions given in Fig. 62 are in about the right proportion. This proportion works so as to give the length as about two and one-quarter times the di-

ameter. It will be found by trial that for a pattern of this size any smaller ratio is insufficient.

The core.box is a half core-box only, and so two half cores are made, baked and then pasted together. The largest diameter of the core is 1 1/2 in. while the smallest diameter, which comes not very far from the middle of the length of the core, is but 3/4 in.; so that it becomes necessary that extra care be taken in finishing the various pieces forming the core-box in order that the sand forming the core can be easily removed from the core-box without breaking away in the slightest degree. Of course small wires could be used in making these cores to aid in holding the sand.

Fig. 64 shows the drawing for a small hand wheel so constructed that the rim may be built separately, the arms, A, Fig. 64, being inserted after the wheel is built. First, cut from a piece of clear, dry pine 1 in. thick a circular block 6 13/16 in. in diamter. Fasten this carefully to the square center plate, and first true up the front surface of the block. Prepare some pine stock 3/4 in. in thickness and lay out on this board quarter circles to be used for building up the rim, allowing 1/2 in. extra stock for turning. The outside radius, therefore, should be about 3 1/4; in., and the inside radius about 1 7/8 in. Carefully saw out this segment and, using it for a pattern, mark out seven other pieces and saw them out to the lines. These segments are to be joined endwise around the circumference of the wood face-plate previously turned. Be sure that each two segments meet in a perfect joint. The edges are to be carefully glued together, and the segments are fastened to the face-plate by screws of small wire brought through from the back of the face-plate. It will, of course, be necessary to put a layer of paper (either brown paper or newspaper is good for this purpose) between these segments and the face-plate. Otherwise the rim would become glued to the face-plate and could not be removed after the turning was completed.

Having completed the first set of segments, put the face-plate on the lathe and turn the front face of the segments true. The other four segments are next glued to the first set, comprising what is known as the second course. These segments should be placed so that the joints will not come directly over the joints of the first set. In other words, the second set of segments will lap over the first, forming a lapped joint. This second course is fastened to the first form with glue, and must be clamped together until the glue is thoroughly set.

Next, place the face-plate on the lathe again and remove the front surface of the second course of segments until the required thickness, 7/16 in. is reached. The outside diameter, 6 in., is next turned, and the inside diameter made 4 1/2 in. The corners of the segments are then cut away with a skew chisel so as to form the circular groove required in Fig. 64. Fig. 65 shows the corners re-moved, and Fig. 66 shows the required half circle.

Carefully sand-paper the pattern when this work has been completed, and next remove the screws which fasten the wood face-plate. The wood face-plate is next to be turned down until the shape shown in Fig. 67 is reached. The pat-tern is then to be forced on to this face-plate, as shown in Fig. 68. The outside corners are next to be removed, so that finally the pattern will take the shape shown in Fig. 69, when it is to be sand-papered. Before the pattern is removed from face-plate, make a line at the point marked A,. Fig. 69, with the acute point of the skew chisel. This line is to be used later in centering the hub. By this I mean locating the center of the hub on the arms after they are inserted in the pattern. The arms are made from stock 7/16 in. in thickness and 1 1/2 in. wide.

Having set the dividers at the radius of the circle marked on the rim, make lines on each end of the piece to be used for the arms, these lines corresponding with the centering circle. Carefully cut out the block on these lines, and next place the arm in position on the rim, marking out the edge of the piece so as to outline the rabbet or pocket which must be cut in the rim in order to receive the arms. Next, cut down to this centering circle and to the other lines, those marked rabbet or pocket being cut half way through the rim. This piece is next set in position, as shown in Fig. 70. The hub, as shown at B, Fig. 64, is now to be turned to the required dimensions. A shoulder may be turned on the hub and a corresponding hole bored in the pattern, or the hub may be simply fastened with glue and nails to the outside surface of the pattern. Finally, cut down the arms to elliptical form, as shown in Fig. 64. The pattern is then to be sand-papered and shellacked.