These slabs are rolled to any required thickness, according to the desired width across the middle of the intended beam ; the thinner the slab, the wider or higher is the beam.

For small slabs, a bar may be rolled to a sufficient length to make several slabs, the bar being afterwards cut with shears into the desired number of pieces.

Large slabs are conveniently made singly, the width of each one being the width of the widest part of the slab when finished. After the component piece is rolled to a proper thickness, the desired shape is next marked upon the side, and the superfluous pieces cut off with a broad steam-hammer chisel. During the trimming of a beam slab, or other similar piece of work, a thick plate of copper or soft iron is fixed to the anvil face, to prevent the chisel edge touching the anvil. The mode of fixing or shaping the fender-plate to a small anvil or anvil-block consists in heating the plate to redness and fixing it between the hammer and anvil; and, while fixed, the portions that extend from the anvil are driven down with sledge-hammers. For such fender-plates, a thick iron plate is preferable to copper, although copper is much used.