A Belt-Driven Power Hammer of To-day
To most of us the steam hammer, still little changed in essentials, is quite well known and some of us have witnessed the cracking of an egg without breaking the egg cup which held it. The adjustment and regulation of these mammoth hammers is so nice that with almost successive blows a skillful operator can flatten a piece of iron and then break the crystal of a watch without otherwise injuring the timepiece. Needless to say, the steam hammer has proved to be the only efficient hammering device for forging large pieces.
Two Board Hammers and Trimming Press
But whether made in the small way of the village blacksmith, by the larger helve, tilt, Bradley, or by the monster steam hammer, each forging, unless made in a die, must be considered to be specially formed and no two pieces, when finished, are exactly alike. They are always “hand made” articles.
Drop Forgings
Many years ago, what are known as duplicate or interchangeable parts, therefore, were quite unknown and it is related that parts of the famous English Enfield rifle were made in various parts of the civilized world, shipped to the Tower of London and there assembled. But during assembly, the various pieces had to be filed and carefully adjusted by hand because no two parts were exactly alike. But the “Yankee tool makers” of New England solved the problem by forging the pieces of which many duplicates were necessary in a “die” or impression in a block of steel. The forged pieces, of course, took the exact impression of the “die” and successive pieces thus made were alike in size and shape. From finished duplicate parts which went to London from the New England states, the Enfield rifle was assembled with very little final finishing of the “cut and try” variety.
Done at first with the die on a blacksmith’s anvil and with a light hammer, this promising method soon developed expert “die-sinkers” (die makers), also ingenious men of whom the term “Yankee Tool Makers” is self-explanatory.
In connection with this work what are known as “drop hammers” came to be largely used. Of these an important type were the “board hammers,” in which the heavy steel hammer-head was attached at the bottom end of a vertical board set between pulleys. As the pulleys squeezed and revolved against the board it was carried up between them and dropped, when the pulleys loosened it at whatever height was desired. Rapidly and periodically ascending and dropping upon the anvil beneath, it quickly forced the white-hot iron into the “die” upon the anvil, forming what have since been known as “drop forgings.”