In the sharpening of saws, a great many files are used. During the War of the Rebellion, Henry Disston & Son (this being the firm name at the time), unable to obtain files which would give satisfaction, found it necessary to make files for their own use.  This becoming known, it was not long before requests were received from customers that they be supplied.

The demand increasing, it was decided to enter the field of filemaking and in 1866 a plant was equipped and additional skilled workmen employed to turn out high-grade files.  As with his saws, Henry Disston always wanted to turn out the best, so he gave his attention to the production of a file that would be superior in quality, shape, and cutting power of teeth.  Although his first files were made by hand, he realized early the necessity of machines in the production of perfect files.

As none of the machines so far invented were considered exactly perfect, the Disston Works carried on extensive experiments for the production of file-cutting machinery that would be adequate to meet every demand.  Their efforts were successful.

In 1877, the Disston Works started to make files by the aid of their own machines.  Constant improvements were made from year to year until today the teeth of Disston files are cut upon the most perfect file-cutting machines.

In 1866, the Sheffield Telegraph, of Sheffield, England, held a contest to reach a final decision as to whether machine or hand-cut files were best. One side of each file used was machine-cut, and the other hand-cut.

After exhaustive tests the firms trying out these files without a knowledge of which side was which, decided in favor of the machine-cut files, which forever settled a controversy that had been waged for two centuries.

As has been shown in the foregoing history of the file, many of the present forms of the file were substantially originated in the earliest days of its history. These have been modified and added to as the knowledge of file manufacture increased and new and different uses were discovered. There are today a large variety of files being made. These various forms will be taken up in the later parts of this article, but we will first consider the making of the modern file. In describing its manufacture the word file is used in its broad sense as applied to both files and rasps, irrespective of either size or form.

Disston Company Make Greatest Variety of Files

Although not the oldest manufacturers of files in this country, the Disston File Works today is well equipped, and turns out the greatest variety of files made. A general description of the Disston methods therefore, will give a clear idea of the manufacture of the modern file.
There are, of course, quite a number of points upon which the high grade file depends for its superiority.

The principal ones are:

1. Tough steel of a high grade suitable for the purpose.

2. Proper forging and annealing.

3. Sharp and well-formed teeth.

4. Thorough hardening.

5. Careful inspection at every stage of the work.

The real basis of the file is the steel. All manufacturers endeavor to obtain the very finest steel possible for the purpose, but the quality of the steel is bound to vary to some extent unless the manufacturer has some way of controlling the output. Steel for making files requires a high percentage of carbon to obtain the requisite hardness.

This carbon-content is apt to vary unless the "mix" is carefully regulated.

Make Their Own Steel

Henry Disston & Sons began to make crucible steel as early as 1855 so that when they took up the manufacture of files they were in a position to obtain steel of a high and uniform quality. The Disston Steel Works, which includes the melting department, rolling mills, steam hammer shop, and trimming room, occupies several commodious buildings. There are laboratories where the chemical and physical tests of the steel are made. Constant experiments with proper ingredients to maintain and enhance its quality are conducted in connection with the steel works.

After the special steel has been carefully and properly melted, it is poured into moulds. When the steel is cool, the mould is removed and the ingot which has been formed is then turned over to the rolling mill, where it is reheated and rolled into large bars. These bars are then cut into smaller pieces, and the pieces are again heated and run through different size rolls, which reduce the diameter, but increase the length. The last roll through which the steel passes reduces it to the particular size and imparts the shape or form desired, such as round, half-round, flat, three-square, etc., each thickness and shape being specially rolled.

It may be of general interest to learn that in rolling steel for a 14-inch flat file, which is approximately 1-7/16 inch wide by 3/8 inch thick, the bar, as referred to above, measures 4 inches by 4 inches, 24 inches long. This is heated and rolled through one roll after another continuously, until it is reduced to the size and shape required for the file and is then approximately 50 feet in length. This long bar or rod of steel is cut in ten or twelve-foot lengths and sent to the file works, where it is cut into multiples the length of the file to be made.

The first step, then, in the actual manufacture of the file is the cutting of these long rods of steel into pieces or sections of the required length. The pieces of steel thus formed are termed file blanks.