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The method to be pursued to make the pattern for the brass, is as follows: Take a piece of wood of sufficient size to form the body of the brass, and make it of the necessary size and form, observing the direction above given as to the bevels; and make the flanges by turning the two halves in one, as explained in a previous example, omitting to turn out the inside, as this would effect no saving, and such boring would weaken the flange, and render it liable to split in attaching it to the body of the pattern. To fasten the flanges, glue them on; and when dry insert brads, setting the flanges by lines. Then pare out the flange even with the bore of the brass. In many cases brasses are dispensed with, and Babbitt metal is employed in their stead. The requisite form of casting for this purpose is shown in Fig. 167, the Babbitt metal being con

Fig.167

tained within the thin ridges which extend all around the edges of the half circular bearing. In addition to this, however, the machinist sometimes drills small holes in the cavity for the Babbitt metal. The ridges are cast solid with the box, and the two at the end (D and E, in Fig. 167) make no difference to the molding, since they will leave the sand readily and easily. But the ridges or strips that extend lengthwise of the bearing, must be made detachable

from the pattern, the strips referred to being held in posi tion by the dovetails shown at C. The recesses to receive the dovetails are first cut out, and the dovetails are made to a neat, fit therein. Then we take the strips required to form the ridges, and having just spotted the faces of the dovetails with glue, while they are in their places, we press the strips against them for a moment, and adjust the strips and leave them in position for the glue to dry. By this means the dovetails are fastened to the strips exactly in the required position. When dry, the strips with the attached dovetails may be withdrawn from the pattern, and should then be more securely fastened together by the addition of screws or nails. In many cases, wires are employed in place of the dovetails; they being inserted, as shown in Fig. 167, at F; and when they are used, it becomes a consideration whether the molder can conveniently extract them. If he can, they are preferable to the dovetails, as these latter are sometimes apt to stick.

Bearings of this class (Babbitt metal) are often formed in the framework of a machine, or in other patterns that do not permit of being molded in the direction suitable for the above example. Fig. 168 represents such an example, which requires to be molded

in the direction denoted by the arrow. It will be advisable to core out the whole space for the cap and bearing, the core box in this case being fitted with the strips in a manner similar to that above described for the Babbitted pillow block. The pattern in this case is made

Fig.168.

as shown in Fig. 169, the space for the bearing being blocked up, and the block extending through, as shown

at A, to form a core print. The core box shown beneath may be, in the smaller sizes, cut out of the solid wood, the

Fig.169

A

part B being made thick, because it includes the thickness of the ridge on that end, and also the depth of the print, as shown at A. The reason that the block or core print protrudes at C, is, that a ridge may be formed in the mold to steady the core while inserting it in the mold; and the depth of the core box, at E, must be made to suit it. It will be noted that the core prints, at F F, are carried to the top of the pattern; and it will be readily perceived that they must be so made in order that the pattern may lift from the sand. Then, after the mold is made, the core for the hole

[graphic]

is first inserted, and then a small core is fitted into the

recess in the mold; and thus is the top part of the recess (above the core print) stopped off. The circles marked on the faces of the prints, F, are to be painted on the pattern in black varnish, and their purpose is to denote that the core proper is round. If these black circles were not made, the pattern maker would

Fig.170.

A

require to make a similar circle and cross marks with chalk or pencil, that the molder may know how the core is to be left.

Fig. 170 is a representation of a pattern for a slide; it has the projections simply set on with pegs, to prevent the pattern being locked in the sand. In molding this piece, a false core is laid between these projections. After the cope is lifted, the plate A may be taken out; and after removing the false core, the pieces B B can be withdrawn.

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CHAPTER XI.

EXAMPLES IN COLUMN PATTERNS.

Our next example shall be for a square or rectangular column, which, though very simple in construction, yet necessitates a departure from the ordinary method pursued in pattern making-the object being to save the making of an entirely new pattern for every required column. In view of the thousands of columns of this kind that have been cast, it is not to be wondered at that measures have been taken to cheapen the cost of the pattern, and lessen the labor in preparing the mold; but it is to be remarked that no one has been able to invent a permanent mold for this class of work. In cast iron columns, the strict rules of architecture are not rigidly followed. The slight but graceful curve prescribed for every column and pilaster is frequently neglected, and various parts of the column are modified in their contour— to their detriment, as may be easily seen by comparing the details of a stone building with those of an iron one.

Square iron columns are usually made parallel throughout their lengths; while, on the end view, two of the sides incline towards one another, on account of the draft or taper given to the pattern. Round column patterns are not made parallel, but are smaller at the cap than at the base. The curve above mentioned is given to the shaft; but as the pattern is made to serve for all lengths of columns of that diameter, the curve can only, in most cases, be an approximation. In foundries that make a specialty of this class of work, numbers of blocks of various sizes and lengths are kept, and they simply require the addition of such ornaments as the design comprises,

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