The term “cut nail” refers to the way the nail was made rather than its use, and distinguishes these nails from wire nails. When the term “wire nail” is used to refer to the method of manufacture, it means a nail made from wire or rod. In this sense, almost all the nails made since 1900, of every type, are wire nails.
In earlier times the cut nail was the usual form. Cut nails are cut from a steel or iron plate, and so have a rectangular cross section. They are not inferior to wire nails; in fact their holding power is about 1.5 times greater than that of a wire nail of the same length – even more in end grain – but they are more expensive to manufacture. They are still made, in most fields as a specialty item prized for their quaint appearance.
A shortcoming of cut nails is that, because they are wedge-shaped, once one starts to come out it will reach a point where it suddenly loses almost all resistance to withdrawal. Wire nails, being uniform cylinders, do not behave that way.
A writer in the American Manufacturer combats the notion that the manufacture of wire nails is far more expensive than that of cut nails. He thinks that if a visit were made to a first-class rod mill, the cut nail adherent would be enlightened soon as to the possibilties of wire nail making. “With an output averaging 80,000 pounds of No. 5 rods per day, with but two furnaces and about a dozen men and boys, wire rods can be made cheaper than nail plate. Between the wire-nail and the cut-nail, so far as quantity is concerned, there can be no comparison. It is singular that there has been so little improvement in the cut nail. The change from iron to steel is a step in the right direction, but a change in the form of the nail is imperative. The bluntness of the cut-nail is its chief defect, and it is a weighty one. The blunt nail destroys the fibre of the wood, through which it is driven; in fact it usually punches a rough hole through it, thus materially lessening the holding power, and by leaving an open space around it, moisture enters and hastens the destruction of the nail by rust. But in all probability, in the near future the improvement of the cut nail will be compulsory, if it is to hold its place against the encroachments of the wire-nail.”
The Mechanical News, vol. 16, no. 2 April 1, 1886. Page 21.
The resistance to drawing which is offered by a nail is due to the friction against its surface offered by the long, tubular fibers composing the wood. These fibers vary in different kinds of wood, in size, hardness, stiffness, distance apart and adhesion one to another laterally. They act differently upon cut nails and upon wire nails; and upon this difference of action largely depends the variation in their holding power. A pointed wire nail, for example, when being driven forces its point between the fibers and presses them apart; and therefore the longitudinal as well as the transverse elasticity of the wood presses the fibers against the nail, unless the wood be badly split. (A simple illustration is given in the case of a wire nail being driven into the flat side of an ordinary broom.} This lateral pressure, caused by the wedging of the nail among the fibers, is the principal means of keeping this nail in place, and it is easy to see that the pressure is exerted almost entirely upon the two sides parallel to the grain of the wood. (See Fig. 1.)
In the case of a cut nail, however, as usually driven, this wedging does not take place, but the cutting edges of the nail shear off the fibers, or bend them down at a large angle as they meet them along the path in which the nail is driven. Then, if the two sides of the nail that are perpendicular to the grain are wedged, as generally they are in case of cut nails, the further down the nail is driven the more these fibers are pressed backwards; and therefore when stress is applied to withdraw the nail from the wood the more these fibers act like barbs and offer strong resistance to withdrawal. (See Fig. 2).
This supposition as to the action of the nails and fibers has been amply borne out by experiments made to test the assertion. The experiments showed that by far the greater portion of the resistance to withdrawal in the case of cut nails was due to the action of the ends of the fibers upon the adjacent surfaces of the nails, and not to the friction of the fibers against the other sides. For example, in a certain case a cut nail driven in the usual manner (Fig. 3, a) required a force of 630 pounds to withdraw it.
The same kind of nail driven between two holes, so that only the ends of the fibers came in contact with it (Fig. 3, b), required 300 pounds; but when driven between two holes, so that only the sides of the fibers pressed against the nail (Fig. 3, c), it offered only 50 pounds resistance. The sum of the fast two resistances did not, of course, equal the first, because in that case there was a combined mutual assistance offered by the fibers which was not given in the second and third instances; but enough was shown to make it evident that the principal resistance to withdrawal comes from the ends of the fibers.
If a cut nail be driven with its wedge parallel to the fibers its holding power is increased, for the nail is held both by the ends of the fibers on two sides and by the friction of the fibers themselves upon the rough wedge faces of the other two sides of the cut nail. In other words, the nail thus driven is held both by the resistance characteristic of the cut nail and that of the wire nail.
Of course driving a cut nail with its wedge parallel to the fibers of the wood is much more likely to split the timber than driving in the ordinary way. Hence that manner of driving is not often adopted.
Conclusions Formed from a Consideration of the Results of the Tests.
1. Cut nails for the same area hold better than wire nails.
4. Pointing the cut nail adds 33 per cent. to its efficiency, but it increases the tendency to split the wood. To avoid splitting, the taper side only of the cut nail might be wedged. If wedged on all four sides, it holds best.
5. Cut nails driven with wedge across the grain are only about 80 per cent. as strong as those driven with the wedge parallel to the grain. This fact does not accord with practice in driving, probably on account of the greater tendency to split the wood.
14. The cut nail holds 1.33 better in Douglas spruce [i.e., Douglas fir] than in redwood; the wire nail about the same in each, with a slight superiority in favor of redwood.
17. In case of a wire nail, the applied stress increases gradually; of a cut nail by jerks and starts. The decrease of holding in wire nails after reaching the maximum is gradual, while in cut nails it falls off suddenly. Hence, a cut nail is not as efficient in holding together pieces of timber subject to vibration as is the wire nail, for the former is more easily loosened, and, being partly withdrawn, loses much of its strength. This results from the fact that the major portion of the resistance comes from the wedge sides of the nail.
18. Cut nails are more likely to split Douglas spruce, and wire nails to split redwood.
21. The cut nail is more efficient when driven into Douglas spruce, but the wire nail is more so in redwood. This fact bears out the theory as to the manner in which a wire nail holds. The lateral pressure of the redwood fibers is greater than that of the fibers of Douglas spruce, on account of the closeness of the grain of the redwood, it having 39 annular rings to the inch, as against 14 for the spruce; and this holds true, notwithstanding that the redwood is softer than the spruce.
The general conclusion from our tests is that for most uses and under most conditions the cut nail is superior to the wire nail.
President Molera.- … Wire nails have been in use in Europe for a number of years, but as far as I have observed they have not been used extensively in this country until within the last four or five years.
The holding power of nails in Douglas Spruce (Oregon Pine) and in redwood (Sequoia sempervirens).
Journal of the Association of Engineering Societies, vol. 20, no. 2 (February 1898).
Pages 114-129. Soule was a professor at the Univ. of California, Berkeley,
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Last revised: 26 January 2015.