Tracing early history. The lathe was the first machine tool. The origin of the lathe. An old definition of turning. The first record of turning operations. Another old-time definition of turning. English classification of lathes. The earliest form of the lathe proper, or the old “Tree Lathe.” The Asiatic wood turner. The “Springpole” lathe. The “Fiddle-bow ” lathe. The essential features of a lathe. The balance-wheel applied to a lathe. The crank, connecting rod and treadle applied to a lathe. Origin of the term “Pitman.” Afoot lathe built by the Author. Its detailed construction. A foot lathe with the balance-wheel located over-head. The friction clutch for foot-power machines.
THE subject of the present work being the lathe and its work, and more particularly its design, construction, and development in our own country and in recent years, and as briefly comprised in our title of Modern American Lathe Practice, our efforts will be directed, first, to a brief notice of its origin and early development and use as a simple hand lathe ; second, to its more modem development as one of the most important machine tools in the equipment of machine shops; and, third, to the various modifications of it, following its development through all its various forms and for the diversity of manufacturing purposes to which it has been adapted up to its present degree of efficiency.
In considering a subject of the vast importance of the modem lathe and its far-reaching influence upon the mechanical world of to-day, it cannot but be interesting to go back to its early history and to trace its progress and development from as far back as we have any authentic knowledge, and step by step to note the changes in its form and usefulness as the mind of the early mechanic developed, new requirements manifested themselves, and improvements in design, construction, tools, and attachments were devised to meet the growing needs.
It is conceded that of all the machines employed by the mechanic to aid him in his work the lathe holds the honor of having been the first machine tool. From it, in one way or another, all other machine tools have been developed; as they are, practically considered, but modifications of it, or special tools for doing quicker and better, the several operations which may be, and formerly were, performed upon the lathe, as we shall later on have occasion to describe and illustrate.
At present, we will look into the origin of the lathe and then trace its gradual evolution and development up to comparatively recent years, say a hundred years or so ago, as their development into anything like mechanical importance has been confined to the last century which has been so remarkable in this respect.
Upon referring to the older records on the subject of lathes and their uses we find this statement: “Turning is the art of shaping wood, metal, ivory, or other hard substances into forms having a curved (generally circular or oval) transverse section, and also of engraving figures composed of curved lines upon a smooth surface, by means of a machine called a turning-lathe. This art is of great importance and extensive application in mechanics, the most delicate articles of luxury and ornament, equally with the most ponderous machinery, being produced by it. The art of turning dates from a very early period, and Theodorus of Samos, about 560 B.C., is named by Pliny as its inventor; but long before this period, the potter’s wheel, the earliest and simplest form of turning-machine, was in general use, as is evidenced by numerous references in Holy Writ.”
Again, we read in an old-time definition of what turning really consists of: “The immense variety of work performed by turning machines necessitates great variations in their construction; but mode of operation is always the same, and consists essentially in fixing the work in position by two pivots, or otherwise, causing it to revolve freely around an axis of revolution, of which the two pivots are the poles, and holding a chisel or other cutting-tool so as to meet it during its revolution, taking care that the cutting tool be held firmly and steadily, and moved about to different parts of the work till the required shape is obtained.”
In England, the various methods of driving a lathe gives a classification to them somewhat different from that in this country. Hence the following: ” Lathes are divided, with respect to the mode of setting them in motion, into pole lathes, foot lathes, handwheel lathes, and power lathes; and with respect to the species of work they have to perform, into center lathes, which form the outside surface, and spindle, mandrel, or chuck lathes, which perform hollow or inside work, though this distinction is for the most part useless, as all lathes of good construction are now fitted for both kinds of work.” Another peculiarly English idea in reference to lathes is this: “Bed lathes are those used by turners in wood, and bar lathes for the best sort of metal work; and the small metal center lathe employed by watchmakers is known as a turn-bench.”
The earliest form of a lathe proper, that is, “a machine for shaping wood into forms having a curved, and generally a circular transverse section, by the action of a chisel or other cutting tool upon the piece, which is rotated for the purpose,” is shown in the engraving Fig. The Old Tree Lathe, and consists, as will be seen, of two pointed pieces A, A of wood serving as centers and each bound to a tree, and supporting the ends of the piece C to be turned, while on the opposite side of the tree is fixed in the same manner a straight piece of wood B, which acts as a rest for the chisel or other tool with which the turning or cutting is to be done. The power for rotating the piece C to be turned is obtained by attaching a cord D to a flexible limb of the tree, passing it one or more turns around the piece and forming in its lower end a loop for the foot of the operator, who rotates the piece towards himself by depressing the foot, bending down the limb by the movement, which, when he raises his foot, returns to its original position, rotating the piece backwards in readiness for another pressure or downward stroke of the foot. The work was slow and laborious, yet from old samples of the pieces thus produced we may see that an extraordinary good quality of work could be done, particularly considering the primitive methods used.
We read that:
” Wood-turners in some of the Asiatic countries go into the deep forests with axes, and with a few rude turning tools and hair ropes build their lathes and turn out objects of beauty and grace, says the Wood Worker. Two trees are selected which stand the proper distance apart near a springy sapling. With his ax the turner cuts out his centers and drives them opposite each other into the trees, which serve as standards. From one tree to the other he places a stick of wood for a tool-rest. With his ax he trims the branches from the sapling, fastens his hair rope to the little tree, gives the rope a turn around one end of the block of wood he desires to turn into shape, and fastens the free end of the rope to a stick which he uses as a foot treadle. When he presses down on the treadle the wood he is turning revolves, and the spring of the sapling lifts the treadle so that it can be used again.”
The next form of lathe to which these crude efforts seem to have led was one in which the flexible limb, though in another form, was used, but the device became very nearly a self-contained machine. A piece of wood formed a bed for the lathe and to this was fixed the blocks forming the centers, which have since become the head and tail stocks of the lathe. The machine appears to have been used in doors, as the flexible limb of the tree had been replaced by a flexible strip or pole, ” fastened overhead” and called a “lath,” from which circumstance some writers think that the name “lathe” was derived. The driving cord was still wound around the piece to be turned. No mention is made of the method of supporting the tool, but it is probable that a strip of wood was fastened to the “bed” for that purpose.
The next improvement in developing the lathe brings its form within the memory of the older mechanics and is shown in Fig. The “Spring-Pole” Lathe‘X’. In this case there is a rude form of head-stock B, and tail-stock E, both constructed at first of wood, and the tail-stock continuing to be so constructed for many years. In this form of lathe the head spindle is first found, having in the earlier examples a plain “spool” around which the driving cord D was wound, and later on a cone pulley constructed as shown in Fig. The “Spring-Pole” Lathe‘Y’, by which a faster speed was possible with the same movement of the foot. The lower end of the driving cord was fastened to a strip of wood F, the farther end of which was pivoted to the rear leg, in the later examples of the “spring-pole lathe,” as it was then called, the bed having been mounted upon legs as shown.
The bed A, was formed of two pieces of timber set on edge and a short distance apart, properly secured at the ends. This afforded a space down through which passed a long tennon formed upon a wooden block answering for a tail-stock E. This was held in any desired position by a wooden key, passing through it under the bed.
What was the early form of rests for this lathe does not seem to be known, but somewhat later the rest was constructed of cast iron and very much as in an ordinary hand lathe of the pattern-maker or wood-turner of the present day, and as shown in Fig. The “Spring-Pole” Lathe ‘X’.
This lathe was used for both wood and metal, the tools being held in the hand as the slide rest had not yet been invented, as will be seen later on in this chapter.
In the use of the spring pole and cord in connection with the cone pulley, as shown in Fig. The “Spring-Pole” Lathe ‘Y’, some workman discovered, probably by turning a heavy piece, that its forward motion would continue when the foot was raised, provided the tool was withdrawn from contact with the work. It was but natural to make the cone pulley of heavier material, as of cast iron, or to weight it with pieces of iron or with lead plugs cast into it, and thus make it serve the office of a balance-wheel and so keep up the forward revolution of the work as long as it was given the proper impetus by the downward strokes of the foot.
Another style of lathe that was used mostly for small work, generally metal work, was called a “fiddle-bow lathe,” on account of the method of driving it. In this lathe, which is shown in Fig. The “Fiddle-Bow” Lathe, the same idea of propulsion is used as in the former examples, that of a cord passing around either the piece to be turned or a rotating part of the mechanism by which the piece was revolved. In this case, however, instead of the resistance of the flexible limb of a tree or of a ” spring pole” acting to keep the driving cord taut, it is held in that condition by the flexible bow F, which is bent to the form shown by the driving cord D. The engraving is an exact reproduction of a lathe, the bed A of which was about twelve inches long and it had a capacity of about two inches swing, that was made by an older brother for the use of the author when he was nine years old, and in the use of which he became quite a boyish expert in turning wood and metals. The head-stock B, and rest C, were formed of bent pieces of wrought iron, and the “spur center” was formed upon the main spindle, the point being used as a center for metal work.
Lathes driven in this manner are still in use by watchmakers and jewelers and a great deal of very fine hand work is performed with them.
The main features in all these lathes were, first, to suspend the work to be done, or the piece to be operated upon, between two fixed pivots or centers; second, to revolve it by means of a cord wrapped around it, or some part of the machine fixed to it, and kept tightly strained by means of some kind of a spring, as an elastic piece of wood; and third, to reduce the piece to be operated upon by means of a tool having a cutting edge which was held tightly against the material to be operated upon, thus reducing it to the circular form required; fourth, that to accomplish this it was necessary to revolve the piece to be operated upon, first towards the cutting tool for a certain number of revolutions, then by a reverse motion of the taut cord to reverse the circular motion, at the same time withdrawing the cutting-tool for an equal number of revolutions. By this method one half the time was lost, as no cutting could be done while the work was running backward.
It was later found that if the flexible pole or “lath” was rather weak and the piece of work to be operated upon was quite heavy, acting as a balance-wheel, its forward revolution was not wholly arrested, but only checked as the foot was raised, provided the cutting-tool was withdrawn from contact with the work a moment before the upward motion of the foot began.
By this it was seen that great advantages might be gained if the lathe could be made to not only revolve continuously in the direction of the tool, but also with the same force, whereby the tool might be kept in constant contact with the work.
Already the pulley, as applied to the spindle of the lathe, was known. The cord wrapped around it and used to rotate it was known. Doubtless an assistant had furnished the power to drive the lathe while the mechanic handled the tools. What would be more natural than the arrangement of a large wheel, journaled to a suitable support at the front or rear of the lathe, and having the cord connected with it as a driver. And with this device and the problem of revolving it by hand, a handle set between its center and circumference would be natural also, and thus came the crank. We do know that somewhat later than this machines were driven in exactly this manner, the large wheel being constructed with a heavy rim and acting as a balance-wheel.
At this stage of development, the large driving-wheel was rather an attachment than a part of the machine itself, and doubtless so remained for a considerable time. The next change was to locate it beneath the lathe bed, directly under the head-stock, and instead of the use of the handle forming practically a crank of long leverage it was constructed as it is in the sewing-machines of the present day; that is, the wheel journaled upon a fixed stud and the previous long handle reduced to a wrist-pin for the attachment of a connecting rod, or in the older phrase a ” pitman,” which term was given to one of the men handling the vertical saw used in sawing up logs into timber and planks in the olden times (and even now in oriental countries), wherein the log was supported over a trench or pit, the upper end of the saw being handled by the “topman” and the lower end by the “pitman” or man in the pit. When these saws were later on mounted in a rectangular frame or “gate” having a vertical, reciprocating movement and operated from a crank-shaft by a connecting rod from the one to the other, this rod took the name of the former man who performed this office, hence the term “pitman.”
The location of this pitman or connecting rod, as has been said, was directly under the head-stock and well within the convenient reach of the operator when attached to a suitable “treadle” whose rear end was pivoted to the back of the machine and whose front end formed a resting-place for the operator’s foot. This arrangement answered very well and was useful when the work of the lathe was near the head-stock, but was not adapted to long work, to accomplish which the operator would need to stand near the tail-stock or even midway between that and the head-stock. To remedy this defect a strip of wood was hinged to the front leg of the lathe at the tailstock end and its opposite end to the front end of the treadle. This was of considerable use, its principal drawback being that while at the treadle end its vertical movement was the same as the latter, this movement was gradually lessened until at the tail-stock end of the lathe it was nothing. Hence, much more power was required to drive the lathe at its center than at the head-stock, and this was rapidly increased as the work was nearer the tail-stock end of the lathe.
To remedy this defect the large driving-wheel was mounted upon and fixed to a revolving shaft upon which was formed two cranks, one near the wheel and the other at the tail-stock end of the lathe. This shaft was properly journaled in boxes formed upon or attached to cross-bars fixed to the legs at each end of the lathe. From these cranks hung two connecting rods whose lower ends were pivoted to two levers pivoted to the rear side of the lathe, and whose front ends were connected by a wooden strip or “foot-board.” The length of these levers was such that the movement of the foot-board was about twice the ” throw” of the cranks, so that with a foot movement of twelve inches the two cranks were about three inches, center of shaft to center of connecting rod bearing.
This was then and for many years the prevailing form of foot lathes and was quite extensively used, not only for turning wood but for iron, steel, and other metals as well.
There were many of the older mechanics who would work the entire day through. At that time, a day’s work was not eight, nine, or ten hours, but “from sun to sun,” or from daylight till sunset, day after day, treading one of these foot lathes and turning out a much larger quantity of work than these crude facilities would seem to render possible.
In Fig. Foot Lathe for Turning Wood or Metals is shown this form of foot lathe that was in use for many years for turning both wood and metals. The illustration is a drawing of a lathe built by the author when he was between fifteen and sixteen years of age. The bed A, legs B, the cross-bars C, C, the back-brace D, and treadle parts E, F, were built of wood, as was also the tail-block G, which was of the form shown in Fig. The “Fiddle-Bow” Lathe, except that beneath the screw forming the tail center was a wooden key g, for keeping this screw always tight, as there was a tendency, from strain and vibration, for the screw to work loose.
The tool-rest was of the usual form, except that instead of a wedge, in connection with the binder H, to hold it in position, or the use of a wrench on the holding-down bolt, an eccentric of hard wood with a handle formed upon it, as shown at J, was used. This was the first occasion where the author saw an eccentric used for a similar purpose. It worked so well that he fitted similar eccentrics to the stops of the three windows in his little workshop to hold the sashes in any desired position when they were raised, and by a turn in the opposite direction to secure them when they were closed.
The large wheel was of cast iron, rescued from a scrap heap, and had only the grooves for the two faster speeds K, L, the part M being made of wood and fastened to the arms of the wheel. A friendly blacksmith forged the cranks in the shaft N, and the eyes in the lower ends and hooks in the upper ends of the connecting rods P, P. These were first made of wood similar to the connecting rods on a sewing-machine with a closed bearing at the top, but the tendency to pinch one’s toes under the treadle when they happened to be accidentally placed in this dangerous position soon
led to the iron connecting rods with the hooked ends whereby the worst that could happen was the connecting rods becoming unhooked. The shaft N rested in wooden boxes, the lower half being formed in the cross-bars C, C, and a wooden cap held down by two wood screws forming the top half. The bearings of the shaft and the cranks were filed as nearly round as they could be made by hand with the means and ability available.
The pattern for the head-stock was made as shown in side elevation in Fig. Foot Lathe for Turning Wood or Metals, with the housings for the spindle boxes as shown in Fig. Spindle Box Housings. The boxes were made in halves, of babbitt metal and cast in place in the head-stock in this manner. The head spindle was located in place and held by a thin piece of wood clamped on the inside and outside of the housing and having semicircular notches in their upper edges and a slight recess on their inner sides so as to provide for making the box slightly thicker than the housing.
The lower halves of the boxes, having been cast slightly higher than the center of the spindle bearings, were removed and filed down to the proper level and then replaced, the spindle again laid in, the strips of wood clamped on in an inverted position and the top half of the box cast. This part projected slightly above the top of the iron casting and was held down by an iron cap having two holes drilled in it which fitted on the threaded studs R, R, which had been cast into the head-stock for this purpose. The spindle had been turned up in an old-style chain-feed lathe, of which more will be said later on. The cone pulley S was of cherry, simply driven on tightly and turned up to the form shown.
The front end of the spindles was threaded but not bored out. Upon this thread was cast a babbitt metal bushing T, having a square hole in its front end, which was formed as follows: With the spindle in its place a wooden mold of proper form was placed around it and, while it fitted the collar on the spindle at one end, was open at its front end. A tapering, square piece of iron of proper dimensions to form the square hole was placed with its small end against the nose of the spindle and held in that position by the tail screw. The opening around it was closed by a piece of wood of proper form and the job was ” poured,” and the bushing afterwards turned up with a hand tool. Into this square hole could be fitted proper centers for turning wood or metal, and by removing the babbitt metal collar a face-plate could be put on for face-plate work.
It will be noticed that the lathe had been arranged for two speeds proper for turning wood and the softer metals, and one speed considerably slower for iron. A piece of belting \ was provided which could be easily removed to shorten the belt the proper amount for this purpose.
The lathe would swing eight inches and take in between centers four feet. It was found that the round belt did not give sufficient driving power and a new spindle cone of only two steps was put on, the iron balance-wheel lagged up for a flat belt, and the pulley M turned down for the same purpose. This permitted the use of a belt an inch and three-quarters wide, and as no regular belting was available when the job was done an old trace from a harness suffering from general debility was ripped open and a single thickness of the leather soaked up in water, dried out, treated with neat’s-foot oil and used with such good results that it was never replaced.
To this lathe was fitted a small circular saw provided with an adjustable, tilting table upon which not only wood but sheet brass could be cut. Another attachment was a small jig-saw that would cut off wood up to half an inch thick.
One of the disadvantages of the usual form of foot-power lathe was the short connecting rod or pitman which thereby formed too great an angle to the center line from the wheel center to the point of attachment to the treadle, thereby increasing the friction and decreasing the useful effect of the foot-power. It was apparently to avoid this condition that a somewhat peculiar form of lathe was devised and built in the railroad shops at Plattsburgh, N. Y., about 1860, and which is shown in end elevation in Fig. Foot Lathe, Driven from a Countershaft. This was an engine lathe of about fourteen-inch swing, built with cast iron bed A, legs B, and all the parts of metal that are now so constructed. Instead of placing the large driving or balance wheel beneath the lathe bed as formerly, the lathe was belted from a cone pulley of three steps on an overhead countershaft C, provided with the usual hangers D. This countershaft was of a length equal to the length of the lathe and had fixed at the end over the head of the lathe a heavy wheel E, into the hub of which was fixed a stud or wrist-pin F, while on the opposite end of the countershaft was fixed a -disc for carrying a similar stud. These formed two cranks to which were fitted long connecting rods G, the lower ends of which were pivoted to the treadles H, whose rear ends were pivoted to the legs B, as at J. The treadles H are located outside of the legs B, and connected by the foot-board K. The weight of the connecting rods G, the treadles H, and the foot-board K are balanced by the proper counterbalance added to the fly-wheel E, as shown. The author knows from personal observation that this lathe would run very steadily and with a good deal of power, and that its general performance was much better than foot lathes of the usual type. Doubtless the momentum of the balance-wheel, cone pulley, and countershaft was very beneficial in maintaining an equable speed under varying conditions of resistance from the operation of cutting-tools and the like, while the cast iron cone pulley on the main spindle did some service in the same direction.
The only disadvantage in this lathe was that it required too long a time to get it up to its regular speed and necessarily too much time was consumed in stopping it, as there was no provision for disconnecting the main spindle from the driving-cone by a clutch mechanism or similar device, as is frequently the case with special forms of the lathes of recent design.
There has been manufactured for some years a special type of friction clutch that is very useful in driving foot-power machinery. It consists essentially of a drum mounted upon and loosely revolving around the shaft to be driven, and having a friction, clutch mechanism contained within it and so operating that the drum will turn freely in one direction but the moment it is revolved in the opposite direction the friction device comes into operation, the drum is firmly clamped to the shaft, which is thus caused to rotate with it. To this drum is attached one end of a flat leather belt, which is wrapped around it several times and its free end attached to the movable end of a treadle, which is usually hinged at the front instead of the back of the machine. In operation, the pressure of the foot acting on the drum by means of the belt rotates it in the forward direction, which causes its friction mechanism to act and revolve the shaft through as many revolutions as there are convolutions of the flat belt around the drum. The rotary motion thus set up is continued by the momentum of a balance-wheel, and as the foot is raised the treadle is caused to follow it, either by the action of a spring similar to a clock spring within the revolving drum, or a spiral spring acting upon another strap, also wrapped around the drum, but in the opposite direction to the one attached to the treadle. By this device several revolutions of the driving-shaft could be produced at each depression of the foot, the treadle frequently passing through an arc of thirty to forty degrees.
This device was particularly applicable to the driving of light foot-power machinery which it did very successfully, and as the strokes of the foot need not be of the same length and were not confined to any certain cadence it was not nearly as fatiguing as the crank device in which the strokes of the foot were always the same distance and with the same speed.
In the above described device, however, the balance-wheel was more necessary and it was also necessary that it should be so arranged as to revolve with a much higher rate of speed than the large wheel of the older form of foot lathe. There was one advantage in this condition, however, that in consequence of its higher speed the balance-wheel could be made of much smaller diameter and consequently much lighter in weight, and therefore occupying much less space under the machine.