CUTTING AND SPLICING BEAMS

At times, the fabricator will be required to split a beam to make a tee shape from an I shape. This is done by splitting through the web. The release of internal stresses locked up in the beams during the manufacturer's rolling process causes the split parts to bend or warp as the beams are being cut unless the splitting process is carefully controlled.

The recommended procedure for cutting and splitting a beam is first to cut the beam to the desired length and then proceed as follows:

Figure 3-36.-Prefab table and steel storage.

Figure 3-37.-Seated connection.

1. Make splitting cuts about 2 feet (60 cm) long, leaving 2 inches (5 cm) of undisturbed metal between all cuts and at the end of the beam (fig. 3-38). As the cut is made, cool the steel behind the torch with a water spray or wet burlap.

2. After splitting cuts have been made and the beam cooled, cut through the metal between the cuts, starting at the center of the beam and working toward the ends, following the order shown in figure 3-38.

The procedure for splitting abeam also works very well when splitting plate and is recommended when making bars from plate. Multiple cuts from plate can be made by staggering the splitting procedure before cutting the space between slits. If this procedure is used, ensure that the entire plate has cooled so that the bars will not warp or bend.

TEMPLATES

When a part must be produced in quantity, a template is made first and the job laid out from the template. A template is any pattern made from sheet metal, regular template paper, wood, or other suitable material, which is used as a guide for the work to be done. A template can be the exact size and shape of the corresponding piece, as shown in figure 3-39,

Figure 3-38.-Cuttiug order for splitting a beam.

views 1 and 2, or it may cover only the portions of the piece that contain holes or cuts, as shown in views 3 and 4. When holes, cuts, and bends are to be made in a finished piece, pilot holes, punch marks, and notches in the template should correspond exactly to the desired location in the finished piece. Templates for short members and plates are made of template paper of the same size as the piece to be fabricated. Templates for angles are folded longitudinal] y, along the line of the heel of the angle (fig. 3-39, view 3).

Accurate measurements in making templates should be given careful attention. Where a number of parts are to be produced from a template, the use of inaccurate measurements in making the template obviously would mean that all parts produced from it will also be wrong.

Template paper is a heavy cardboard material with a waxed surface. It is well adapted to scribe and divider marks. A combination of wood and template paper is sometimes used to make templates. The use of wood or metal is usually the best choice for templates that will be used many times.

For long members, such as beams, columns, and truss members, templates cover only the connections. These templates may be joined by a wooden strip to ensure accurate spacing (fig. 3-39, views 1 and 2).

They may also be handled separately with the template for each connection being clamped to the member after spacing, aligning, and measuring.

In making templates, the same layout tools discussed earlier in this chapter are used. The only exception is that for marking lines, a pencil or Patternmaker's knife is used. When punching holes in a template, keep in mind that the purpose of the holes is to specify location, not size. Therefore, a punch of a single diameter can be used for all holes. Holes and cuts are made prominent by marking with paint.

Each template is marked with the assembly mark of the piece it is to be used with, the description of the material, and the item number of the stock material to be used in making the piece.

In laying out from a template, it is important that the template be clamped to the material in the exact position. Holes are center punched directly through the holes in the template (fig. 3-40), and all cuts are marked. After the template is removed, the marks for cuts are made permanent by rows of renter punch marks.

It is important that each member or individual piece of material be given identifying marks to

Figure 3-39.-Paper and combination templates.

Figure 3-40.-Use of template in laying out a steel channel.

correspond with marks shown on the detail drawing (fig. 3-41).

The ERECTION MARK of a member is used to identify and locate it for erection. It is painted on the completed member at the left end, as shown on the detail drawing, and in a position so that it will be right side up when the member is right side up in the finished structure.

An ASSEMBLY MARK is painted on each piece on completion of its layout so that the piece can be identified during fabrication and fitting up with other pieces to form a finished member.

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