from The Wise Fisherman's Encyclopedia
Ferrule Materials. Physical requirements of materials intended for use as fishing rod ferrules are enumerated as follows: (1) high tensile strength; (2) adequate fatigue life; (3) freedom from any tendency to seize or stick, with consequent tendencies toward difficult assembly or disassembly; (4) corrosion resistance; (5) light weight, and (6) attractive appearance. Surprisingly, very few metals satisfy these specifications.
Nickel silver. An alloy used for years, 18% nickel silver, remains preeminent in the
field of ferrule material. It consists of 18% nickel, 12—18% zinc, and the remainder
copper. When polished, a bright silver-like finish is obtained which retains its luster
for a year or more. A slow oxidation takes place on the unprotected surface, gradu-
ally turning it pearl gray in color. Varnish or lacquer, of course, will preserve the
original buffed finish indefinitely.
When cold drawn to "hard temper," the alloy's ultimate tensile strength of 105,000 pounds per square inch may be realized. This means, in practice, that very thin wall sections, with consequent light weight, will perform satisfactorily on rods built of any of the rod-building materials in current use.
The proportion of nickel used in the alloy appears to be somewhat critical, not so much from the standpoint of strength, but rather from the consideration of "feel", i.e., the smooth, yet firm, engagement characteristic of the 18% alloy, versus the erratic, dragging fit brought about by the increase of nickel content to 20%. Addition of zinc to the alloy obtains a 'greasy," self-lubricating property permitting easy joining and disjoining of the rod. Fatigue life, although not measured, appears to be more than adequate, except in regions of excessive stress. This is not to be construed as a failing inherent to the material, but rather an inadequate ferrule design.
Brass. Hard drawn, bright plated, brass ferrules are extensively used on low wade rods for reasons of economy. Properly fitted, these are an acceptable item in their place. Fatigue life is short compared to nickel silver. Hard drawn brass, in addition, has a tendency to crack with age. Resistance to corrosion is poor except where plated.
Aluminum. Aluminum ferrules were presumably first made commercially in Great Britain. Early examples were used principally on salmon rods. One design incorporated a male ferrule fitted with an integral pin on one side. When assembled, this pin, or key, fitted into a slot milled in the edge of the female ferrule. Such and arrangement prevented one section from twisting out of alignment. As a locking means, a shouldered nut tightened by hand held the two ferrule members together. It is needless to point out the fact that the whole was quite bulky. The fundamental oversight in this case involved the choice of material. Closely fitted aluminum members are characteristically difficult to assemble, and in some cases practically impossible to dismantle, unless surface-treated or lubricated. Aluminum alloys with anodized surfaces have been used in the manufacture of ferrules since the close of World War II, but have enjoyed no widespread acceptance. The hard surface is extremely thin, and although performing quit well when new, wears rather rapidly to expose the untreated metal below. Fretting, galling, and difficult assembly follow as a natural course. Furthermore, wall thicknesses were on the average too thin, resulting in excessive working stresses which in turn, caused fatigue failures.
Beryllium Copper. Beryllium copper has been suggested and tried as a ferrule material. Although the "feel" is fair
when newly machined, this material deteriorates rapidly as the copper oxidizes, becoming very harsh. Combinations of
beryllium copper and monel, etc., have been made without indication of improvement.
Ferrule Manufacture. Tube making is done by three methods. Two, previously
described, involve the use of flat basic stock. In the third method, the metal
begins as a pierced billet. A hard steel rod or mandrel is inserted in the hole, and both work and
mandrel are gripped tightly at one end and pulled together through a die. The die, being of
somewhat smaller diameter than the metal billet, lays the material tightly against the steel mandrel.
This process is repeated several times, with each operation successively reducing the wall thickness
by causing the metal to flow along the mandrel. The steel rod is withdrawn and the billet softened
by heating (annealed). At this stage the billet is considerably longer than it was at the
start, but its wall thickness is somewhat reduced. The operation is then repeated,
smaller mandrels being employed each time, until the desired size of the tube is
attained. Although the tube may have been cut many times in the process, the
original volume of metal is still present but in a greatly elongated form.
The presence of the mandrel is of utmost importance. It not only determines the
exact inside tube diameter, but constitutes the buttress which controls the direction
of flow of the metal. Each passage through the die not only compresses the metal,
but aligns the microscopic metal particles so that they lie parallel to each other.
Brought to red heat, the particles revert to their former random pattern, the tube
becoming quite soft and easily bent. Silver soldering, then, is disastrous to a cold-
worked temper, as normal fusing temperatures are in the 1000 F to 1200 F range, or
red hot. Lead-tin solder of equal proportions of lead and tin, which melts at
approximately 400 F, should be used. Very little, if any, loss of strength will be
noted until temperatures exceed 500 F.
A few custom rod makers draw their ferrule stock by hand, using heavy presses for the work. In this way they not only control hardness, but can make any size ferrule desired without excessive tooling expense for the relatively small number of parts they require. One mandrel and one set of dies are used for any given size, each piece so drawn being very nearly an exact duplicate of the last. These are short pieces, only slightly longer than required. Rough ends are trimmed and burrs removed. The male center is turned in a lathe to provide a slightly loose fit in the shoulder. These are then tinned and soldered together. A plug or cap is applied to close the small end. The open end is then tapered and serrated, or slotted. In making the female ferrule, a tightly-fitting plug is inserted inside at approximately midpoint where it is soldered securely. The welt, or reinforcing ring, is then slipped over the end, this being soldered flush with the open end. The opposite end is tapered and serrated in the manner previously described. Both elements are then boiled in a strong solution of washing soda to neutralize the fluxing acid used in soldering, and to remove all traces of grease, dirt, etc. After thorough rinsing in hot water and drying, the parts are ready to be mounted to the rod sections.
Precision drawn tubing can be purchased in continuous lengths, but is very costly if tolerances are held to plus or minus one thousandth (± .001") of an inch. Diameters of well-made, properly-fitting ferrules are only one-fifth, or two ten- thousandths of an inch (.0002"), of this figure. The methods of the custom maker, unfortunately, cannot be directly applied to volume manufacture. Mass produced ferrules are almost invariably "formed," rather than drawn in the sense described above. Flat sheet stock is employed in place of partially finished tubes. The mandrel, or punch, acts primarily as a plunger. The metal being shaped seldom bears against any portion but the end of the mandrel. No "ironing" (controlled flow) of the material occurs between die and mandrel. The metal is merely stretched progressively from its original disk shape into tubular form, closed at one end. The operations are automatically fed and occur very rapidly. Fit, in most cases, is quite poor, due either to taper or an out-of-round condition in one or both of the ferrule members.
Since the cost of the individual components used in the fabrication of low and medium-priced rods must be in keeping with the selling price, compromises must be made all along the line. Amateur rod makers need feel no reason to compromise. Their first efforts will be considerably short of perfection. As proficiency is attained, however, they will become critics of their own work. Since most of the accessories are of a durable nature, all of these should be of best obtainable quality.
Mounting Ferrules. There are but few methods by which the ends of bamboo rod
sections may be properly rounded or turned to fit within the spaces provided in the
ferrule members. Regardless of the method used, a tight fit is essential for a sound
joint with bamboo, impregnated bamboo, and the various types of glass fiber-
plastic. Metals on the contrary, should have a slightly loose fitting, as the solder will
fill in the gap.
In the former case an interference fit of .001" to .002" is considered correct. This means that the rod end is made slightly larger in diameter than the inside dimension of the ferrule. The above materials are thermoplastic to varying degrees; that is, when heated to temperatures not exceeding 200 F, these substances will yield just enough to slip easily in place, resulting in an exceedingly close line of contact. The ferrule cement, or preferably one of the adhesive bonding liquids functions satisfactorily as a lubricant.
The actual turning operation can be performed on a wood-or metal-turning lathe using ordinary methods and very sharp tools. All measurements should be made with an ordinary machinist's micrometer. Some factories use specially designed "pencil sharpeners," i.e., rotating cutters in which the rod end is inserted. In the event that serrated or slotted ferrules are used, the turned diameter must be "blended," as illustrated in Figure 2. Thus treated, the shape is gradually changed from multi-sided to round, beginning at the thin, slotted edge of the ferrule and becoming fully round at the inner extremity of the slotted finger.
Rod Sections intended for use with tapered end, unslotted ferrules are similarly treated. In this case the thin edge is hammered lightly with a wooden or plastic hammer as the thin edge begins to interfere with the blended region. The open end of the ferrule is thereby shaped to follow the contour of the rod. Square corners should be severely avoided as breakage will inevitably occur at those points.
Many brands of ferrule cement are available. Most are composed chiefly of rosin, linseed oil, beeswax, gutta-percha, etc., and sold in lump or stick form. To use, the cement stick is held momentarily in a flame which softens the mixture. It is then daubed on the rod end, reheated, and the ferrule (also warmed) pushed into place. On cooling, the cement hardens.
The hard, brittle character of these rosin-base cements is a distinct disadvantage. Under the stress of repeated casting, the substance is reduced to powder, completely incapable of holding the ferrule in place. Ideally, then, a rock-hard, unyielding bond between the metal and rod section would be most desirable. The two joined members would then be virtually "welded" together. To date, no such bond has been unearthed by the rod-making craft, although several satisfactory adhesive bonding agents are available.
These adhesives are easy to apply, and when cured display an exceedingly tough, slightly elastic character which allows the wood (or fiber glass) rod section imperceptible freedom along the bonded seam. The same elastic permits slight shrinkage of the rod from the ferrule (due to excessive drying) without detrimental effect. The use of pins, or other locking devices is unnecessary. Care must be exercised that all traces of moisture, oil, grit and dirt be removed before the adhesive film is spread.