Hand or Simple Turning: Principles and Practice
592
Hand or Simple Turning: Principles and Practice
592eBook
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| ISBN-13: | 9780486156224 |
|---|---|
| Publisher: | Dover Publications |
| Publication date: | 03/12/2013 |
| Series: | Dover Woodworking |
| Sold by: | Barnes & Noble |
| Format: | eBook |
| Pages: | 592 |
| File size: | 17 MB |
| Note: | This product may take a few minutes to download. |
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Hand or Simple Turning
Principles and Practice
By John Jacob Holtzapffel
Dover Publications, Inc.
Copyright © 1976 Dover Publications, Inc.All rights reserved.
ISBN: 978-0-486-15622-4
CHAPTER 1
INTRODUCTION.
THE symmetrical beauty, and necessity of the cylindrical form to the wants of mankind, in an endless variety of utensils and implements, the daily requisites of civilization; in the construction of the tools and machines for manufactures, locomotion, science, and the spread of knowledge; are it is submitted too apparent to demand more than mere allusion, even in a volume devoted to its production by the practice of turning. Readily obtained in all materials, directly or indirectly in the lathe or some of its modifications; the circular form has been always met with more or less exactly, appearing in many natural objects, such as the reeds and canes, in trees, flowers, fruits and seeds, in the egg, in pebbles, shells, and many animal structures. It may fairly be presumed therefore that its characteristics were appreciated and copied by the earliest races of mankind, and although we have no knowledge of the time and manner, in which the handicraft of turning arose and first progressed, it will be allowed that inferences on these interesting points, may be drawn from observation of several primitive lathes still used, and followed in other early but more advanced lathes, of which there exist records.
The practice of the art may be traced back to a very remote period, probably the earliest evidences being the numerous works that have been found among Egyptian antiquities, at Thebes and other cities; very many of which exhibit indubitable signs that the material while in revolution, was subjected to the action of a tool held at rest. Among these, the legs of stools and chairs and other long objects, were probably turned after the same simple method now followed by the Indian and the modern Egyptian; but it is curious, that among all the sculptured records of the trades and occupations, which so vividly represent the customs and habits of the ancient Egyptians, no example of the lathe has hitherto been met with. The potter and his wheel, however, are depicted in these sculptures, and they are frequently mentioned in the earliest writings; this form of the lathe, which has received little material modification to our time, was doubtless employed for the production of much of the antique pottery left by early nations; some of which, like the unrivalled vases of the Etrurians, attest unsurpassable taste and skill.
The lathe was undoubtedly commonly used by the Greeks and Romans; among their authors both Cicero and Pliny refer to the turners or vascularii, while Herodotus uses the lathe as a familiar simile. "But I smile when I see many persons describing the circumference of the earth, who have no sound reason to guide them; they describe the ocean flowing round the earth, which is made circular as if by a lathe" (Herodotus, Book IV. Chap. 36. Cary.); but unfortunately, it appears that none of these nor other early writers have left us any account of the lathe and tools employed by their contemporaries. It would appear probable, that the origin of the lathe may be found in the revolution given to tools for piercing objects for ornament or use. At first, it may be supposed, that a spine or thorn from a tree, a splinter of bone or a tooth, was alone used and pressed into the work, as we should use a bradawl. The process would naturally be slow and unsuitable to hard materials, and this, probably suggested to the primitive mechanic, the idea of attaching a splinter of bone or flint to the end of a short piece of stick, rubbing which between the palms of his hands would give a rotary motion to the tool.
Increased range of motion with proportionate rapidity in the cutting or abrasion, would be obtained by wrapping a cord once or twice around the shaft and alternately pulling the ends; the opposite end of the tool revolving in the cavity of a shell or stone, held in the hand or placed against the chest. This would be the exact type of the reciprocating drill and drillbow, tools common to all nations and in every day use. And granting these few steps in procedure, the pole or bow lathe may easily have followed. The shaft of the drill tool has been assumed as supported at both ends and driven by the cord; it now only requires the supports to have been fixed and pointed, and a cutting tool to have been applied against the work while in revolution, for the arrangement to have become the type of all the different lathes with reciprocating motion.
An illustration of the early use of the drill and drillbow, fig. 1, taken from Rossellini's great work on the Egyptian and Nubian monuments, distinctly shows the drill to be inserted in a wooden shaft, which has apparently itself been turned, having a spherical cap to which the pressure of the one hand is applied, whilst rotation is produced by the bow held in the other. The spherical cap may also have been turned to shape, but it was sometimes a natural object, Sir Gardiner Wilkinson pronouncing some discovered, to have been made of the fruit of the don palm. Another of Rossellini's illustrations, fig. 2, shows the workman to be piercing three small holes close together by a rather unusual method; the drills are separated by the fingers of the left hand and the bowstring envelopes them in succession, the pressure being now given by the weight of the enlarged mass at the top of each.
A different contrivance for giving the drill reciprocal motion, probably as ancient, fig. 3, is used by the Chinese, and obtains also to some extent among ourselves. The drill stock passes freely through a hole in a cross staff, from either end of which a single string is carried through an eye, pierced at the top of the drill shaft, above which is a weight or bulb of metal to give momentum. The operator first coils the string around the drill shaft, the shortening of the string causing the ascent of the cross staff; he then sharply depresses the cross staff, which uncoiling the string turns the drill as many times as there are coils. The pressure by the hand is only given at the first moment of the descent of the cross staff, but the momentum continues the motion, and winds up the string in the opposite direction, ready for the succeeding stroke. This old form of drill is used by the glass and china menders for piercing the holes for the insertion of the small metal staples called rivets, afterwards cemented in position. Other artizans occasionally employ this pump drill, but in Europe, the weight is usually shifted to the lower part of the spindle, fig. 4, to lessen the disposition to upsetting.
It may be surmised, that the Indian or Eastern nations were among the earliest to follow the art of turning, and that later, their method of practising the art was carried by the Arabian and Moorish nations, to the furthest extent of their conquered territories; while thence from Spain it was transported to South America. The strong analogy that exists between the lathes used in the present day, by the Hindoos, the Persians, the large group of Moslems, the Spaniards and some of the South American nations, proving this to be far from hypothetical; and the same turning lathe appears to have remained in use by these peoples without considerable improvement, from its early rude construction until now.
It is unfortunate that so little is known of the early history of the lathe in Europe, but it would appear probable that the exchange of the sitting for the upright posture of the operator, as more congenial to the habits of the European, must have soon led to important modifications in the construction of the apparatus. The greater elevation of the lathe, thus permitted the introduction of the pole and various attempts at improvement in that method of giving motion. The pole lathe and the bow lathe, of both of which we have descriptions in the earliest known work exclusively on turning, were eventually superseded by the lathe with continuous rotatory action; but the former is still valuable and remains in use for some purposes. During the last century the development and improvements in the lathe and its congeners have been rapid and continuous, always keeping at least equal pace with the increased requirements of the time.
SECTION I. — THE INDIAN, PERSIAN, ARABIAN, AND OTHER LATHES. THE CHINESE LATHE.
The lathe found in use among the natives of India, fig. 5, still remains the same primitive apparatus that has been considered as the probable starting point of turning. The practice is as follows; — when any portion of household furniture has to be turned, the wood turner is sent for; he comes with all his outfit and establishes himself for the occasion at the very door of his employer. He commences by digging two holes in the ground at a distance suitable to the length of the work, and in these he fixes two short wooden posts, securing them as strongly as he can by ramming the earth and driving in wedges and stones around them. The centers, scarcely more than round nails or spikes, are driven through the posts at about eight inches from the ground, and a wooden rod for the support of the tools, is either nailed to the posts or tied to them by a piece of coir or cocoa-nut rope. The bar, if long, is additionally supported as represented, by being tied to one or two vertical sticks driven into the ground. During most of his mechanical operations the Indian workman is seated on the ground, hence the small elevation of the axes of his lathe. The boy, who gives motion to the work, sits or kneels on the other side of it holding the ends of the cord wrapped around it in his hands, pulling them alternately; the cutting being restricted to one half of the motion, that of the work towards the tool. The turning tools of the Indian are almost confined to the chisel and gouge and their handles are long enough to suit his distant position, while he guides their cutting edges by his toes. He grasps the bar or tool rest with the smaller toes and places the tool between the large toe and its neighbour, generally out of contact with the bar. The Indian and all other turners using the Eastern method, attain a high degree of prehensile power with the toes, and when seated at their work not only always use them to guide the tool, but will select indifferently the hand or the foot, whichever may happen to be the nearer, to pick up or replace any small tool or other object.
The limited supply of tools the Indian uses for working in wood is also remarkable, they are of the most simple kind and hardly exceed those represented in fig. 5. The most essential in constructing and setting up his lathe being the small single handed adze, the Basslh, referred to page 473, Vol. II. With this he shapes his posts and digs the holes, it serves on all occasions as a hammer and also as an anvil, when the edge is for a time fixed in a block of wood. The outer side of the cutting edge is perfectly flat, and with it the workman will square or face a beam or board with almost as much precision as if it had been planed; in using the bas-soolah for this latter purpose the work is generally placed in the forked stem of a tree, driven into the ground as shown in the illustration.
The method followed by the Persian turner, fig. 6, is not quite so rude. In his lathe the centers are made to pass through the ends of an open box, the edge of which serves for the support of the tool; they are raised or lowered to suit work of different diameters in a series of holes pierced in a vertical line. Small works are set in motion by the bow, both by the Persian and Indian, for those of larger diameter, both use a cord pulled by an assistant; but, when using the cord the Persian lathe is fixed by means of stakes to prevent its being pulled along the ground. Excepting the portable box the turning apparatus and manipulation thus differ but little from those last described.
The lathe used by the Arabian and Moslem group of turners, is shown by fig. 7, drawn from a sketch by the author, made in 1873 in one of the numerous turners' shops in Cairo. The Arab's lathe although roughly constructed presents several improvements over those of his Eastern brethren; it is more complete and is adjustable to works of different lengths. The apparatus is formed of two wooden feet or cross pieces, about six inches square by three feet in length, carrying two iron centers towards their ends; a longitudinal wooden stretcher about five or six inches wide, is fixed to the left foot and passes through a corresponding mortice in the right, within which it can be fixed by a wooden wedge. When the work is fixed between the centers, the four parts form a rectangular frame, which the width of the longitudinal piece in great measure prevents from racking and retains moderately square. The tool rest consists of a heavy iron bar laid across the two feet, and is adjusted to the height of center by separate pieces of wood placed between it and the cross feet. The center points being adjusted to the length of the work and the stretcher fixed by the wedge, the machine is retained stationary whilst in use by four loose spikes, which pass through holes in the feet and are slightly driven into the floor.
The operator sits upon one heel, the toes of the foot going just under or upon the stretcher and he directs the tool, which he holds by a long handle, with the toes of the other foot; the position being much like that of the Indian fig. 5, except that the whole body is more compactly held together. Occasionally and for heavy work, both feet are advanced, placed close together, and press the tool on the bar by the big toes, the other toes closely pressed around the tool and on the bar; while the latter is always pushed forward by the feet and withdrawn by the hands, as may be required to regulate its distance from the work.
The tool or the bow are held indifferently in either hand, as the work may render more convenient; but, the left hand and the right foot for the tool, with the bow in the right hand appears most general. The bow presents a peculiarity in the hinged piece near the handle, employed to regulate the tension of the string; the string is wrapped once or twice around the work, after which it is twisted round the jointed piece, which is then folded back and held in the hand with the handle. A stick is used for the support of long work of small diameter; one end is placed beneath the stretcher and a wedge or rough piece of wood between the stick and the floor, forces the other end up to the work and opposes the thrust of the tool; the arrangement being analogous to the simple support fig. 132. When turning many pieces of one size, the Arab employs two slips of wood sometimes jointed together fig. 8, with an opening the size of the work. He uses the same contrivance for internal turning and boring; one center point alone being used, the other extremity of the work being held in the circular aperture of the double bar. The Arab turner works nearly as much in public as the Indian, his workshop being a small square room, the front entirely open to the street, with the floor upon which he sits about three feet above the level of the road. He, also, will carry his lathe to his work, and it is his daily practice when the sun shines too powerfully, to quit his workshop, and carrying his lathe over to the opposite and shady side of the street, to establish himself on the ground in front of the shop of one of his neighbours; driving the spikes into the hard sand forming the road, to retain his lathe stationary.
The lathe, although of so rough a description, has been most effectively employed for centuries, for the production of a peculiar and very beautiful ornamental wood work, for the interior decoration of Mosques and houses, for screens, seats and other objects, and for the Arabian lattice windows called "Meshrebeeyeh." These oriel windows, have all those portions which are usually of glass, entirely filled by open, turned, wooden latticework, formed of an infinite number of small turned pieces something like the bails of a wicket, but jointed and fixed one into the other. The work is sufficiently close to impede the passage of light and sun and to conceal the inmates from observation by the passers by, while still allowing a free passage to the air.
(Continues...)
Excerpted from Hand or Simple Turning by John Jacob Holtzapffel. Copyright © 1976 Dover Publications, Inc.. Excerpted by permission of Dover Publications, Inc..
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Table of Contents
Contents
Title Page,Copyright Page,
PREFACE,
Table of Figures,
CHAPTER I. - INTRODUCTION.,
CHAPTER II. - CENTER LATHES WITH CONTINUOUS MOTION.,
CHAPTER III. - LATHES WITH REVOLVING MANDRELS.,
CHAPTER IV. - MODERN FOOT LATHES.,
CHAPTER V. - APPARATUS ADDED TO THE LATHE FOR SPECIFIC PURPOSES.,
CHAPTER VI. - CHUCKS AND APPARATUS FOR FIXING THE VARIOUS WORKS IN THE LATHE.,
CHAPTER VII. - THE ELEMENTARY PRACTICE OF SOFTWOOD TURNING.,
CHAPTER VIII. - THE ELEMENTARY PRACTICE OF HARDWOOD AND IVORY TURNING.,
CHAPTER IX. - ELEMENTARY METAL TURNING.,
CHAPTER X. - SCREW CUTTING.,
CHAPTER XI. - THE SPHERE, AND VARIOUS FORMS IN HARDWOOD AND IVORY DERIVED FROM THIS SOLID.,
CHAPTER XII. - PRACTICAL EXAMPLES OF SIMPLE, PLAIN TURNING IN WOOD AND IVORY.,
CHAPTER XIII. - PRACTICAL EXAMPLES OF COMBINED PLAIN TURNING, EXECUTED WITH THE HAND TOOLS ALONE.,
CHAPTER XIV. - MISCELLANEA IN PLAIN TURNING IN WOOD AND IVORY. DYEING, STAINING, AND DARKENING.,
INDEX.,