This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
All hammers for hand use, whether chipping hammers or sledge hammers, should be made entirely of steel. The practice of welding steel faces to iron eye portions in order to avoid using a larger quantity of steel, is more expensive than making the entire tool of one piece of steel, and an unsound inferior tool is made instead of a good one. The steel selected for hammers is a tough cast steel, and may be termed a soft fibrous steel that will bear hardening. Cast steel which has been well wrought with rolling and hammering is suitable for hammers, and but little forging is necessary if the metal selected is of proper size. The small chipping hammers and other hammers for vice work are easily made of round steel, but the larger sizes, termed sledge hammers, require to be made of square bar steel. When several are to be made, a long piece is selected, that each hammer may be forged at one of the bar's ends, thus avoiding a great portion of the handling with tongs. While the work is attached to the bar, it is punched and drifted to shape the hole, and also thinned with top and bottom fullers at both sides of the hole.
The greater part of the forging is thus effected previous to cutting the hammer from the bar, and when cut off, all rugged portions at the extremities are carefully trimmed off with a sharp rod chisel, that the faces of the work may bo solid.
A good hammer is that which has a long hole to provide a good bearing for the handle, and which has the metal around the hole curved with punching and drifting, the hole being oval, as in Fig. 104, and tapered at both ends or entrances of the hole. The entrances of the hole are principally tapered at the two sides which are nearest to the hammer's faces, the other two sides being nearly parallel. Steel taper drifts of proper shape are therefore driven into both ends of the hole, to produce the required form, and all filing of that part is thus avoided.
The making of small sledge hammers is conducted by forging each one at the end of a bar, similar to the mode for chipping hammers, but a sledge hammer, about 20 lb. in weight, is made either singly, or of a piece of steel which is only large enough to be made into two; the handling of a heavy bar is thus avoided. By referring to Fig. 105, it may be seen that the handle hole or shaft hole of a sledge hammer is comparatively smaller than that of a chipping hammer; this is to provide a solid tool that will not quiver or vibrate when in use, and is therefore not liable to break.
Very little filing is sufficient to smooth a hammer, if properly forged, the shaping being easily effected with fullers and rounding tools; and after being filed, each of the two ends is hardened, but not afterwards tempered. After hardening, the two ends are finished with grinding on a grindstone. Polishing the faces of engineers' hammers is not necessary.
Through the handle hole of a hammer being tapered at both ends, the shaft end is made to resemble a rivet which is thickest at the two ends, one part of the shaft being made to fit one mouth of the hole with filing or with a paring chisel for wood, and the outer end of the shaft being made to fit the other mouth of the hole by spreading the wood with a wedge. The wood for the shaft is ash, and is fitted while dry, so that the handle requires hammering to force its end into the hole, and when the hammering has made the taper shoulder of the shaft end bear tight against the taper mouth of the hole, the driving ceases, and the superfluous wood extending beyond the wedge end of the hole is cut off, and the wedge hammered into its place. This wedge is of iron, and has an angle of about 5° or 6°; consequently, the mouth of the hole should have the same angle, to cause the wood to fill the hole when a wedge is driven in. The principal taper of the wedge is in its thickness, its width being nearly parallel, to make it hold tight to the wood. When it is to be put in, it is placed so that its width shall be parallel with the parallel sides of the hole, the taper part will then spread the wood in the proper direction.
An additional means of tightening the wedge consists in making a few barbs upon the edges, and also cleaning and chalking it when it is to be hammered into the wood.
In order to produce a large number of hammers of the same shape and dimensions, each one should be shaped while between a couple of top and bottom springy shapers. This shaping is effected near the conclusion of the forging, and the hammer being shaped, is held with a long handle drift, whose point extends a few inches through the hammer, and also beyond the shapers, the length of the hammer being at right angles to the length of the drift. After such shaping, the mouths of the hole may be tapered with a drift or with filing; to avoid filing, a short taper drift is used for tapering the mouths of the hole, and the long handle drift for holding the hammer in the shapers is provided with a taper shoulder, to fit the taper mouths of the hole; and when a hammer is to be put between the shapers, this drift is hammered tight into the hole until the taper shoulder of the drift bears on the taper mouth of the hammer.