High Speed v. Carbon Steel.

In the heavy machine shops (on tough and high tensile metals) high speed steel is supreme, and no workshop manager would tolerate the use of carbon steel. Where soft metals are machined, carbon steel not only holds its own but is essential to output, lower steel costs, and high-class finish. This is due to the fact that no high speed steel reaches the same test of hardness that can be obtained and maintained with carbon steel (subject to the material being kept at a low temperature).

In large brass machine shops, where articles require a high finish prior to lacquering, or bronzing and polishing on the buff, all such work is machined very, smoothly, wrapt in tissue paper, and sent direct to the lacquering shop. The tools used on this class of highly finished work are called “Planning Tools,” and are made exclusively of carbon steel.

These same tools, after being ground to the required shape, are finished off on a smooth oilstone, and when correctly finished they produce a polished mirror-like surface on the work that page 35 only an expert can detect from the machine mop and buff finish.