We know that a Frenchman by the name of Jacques Berson, in 1569, built a lathe that seems to have been capable of cutting threads on wood. An engraving of his lathe is given in Fig. 9.

As will be seen in this engraving it was a large, clumsy and cumbersome affair, considering the work it was designed to perform. While the various parts of the machine are not very clearly shown, enough is given to show us that he had a wooden lead screw to give the pitch of the thread by means of a half nut which appears to have been fixed in a wooden frame, to which in turn the piece to be threaded was attached by being journaled or pivoted upon it. The lead screw and the piece to be threaded were both revolved by means of cords wound around spools or drums upon a shaft overhead, and held taut by weights instead of the flexible spring pole already described. These cords were fastened to a vertically sliding frame, also balanced by cords and weights, and to which was attached a sort of stirrup adapted to the foot, by which the machine was operated.

Fig. 9.   Berson's French Lathe, built in 1569.

Fig. 9. - Berson's French Lathe, built in 1569.

Considering the early time at which this lathe was constructed, it shows a good deal of ingenuity and may well have been the forerunner of the developments in this line which came after it.

It is a matter of record that in 1680 a mechanic by the name of Joseph Moxan built lathes in England and sold them to other mechanics, but we do not possess any certain or authentic knowledge of their design, as to whether or not screw threads could be cut with them or whether they were designed for work on wood or metals, or both. In all probability they were foot lathes and used on all materials that had been formed in a lathe up to that time.

In the year 1772 the French encyclopedia contained the illustration of a lathe which was provided with a crude arrangement of a tool block or device for holding a lathe tool and adapting it to travel in line with the lathe centers. By this it would seem that the inventor had some idea of the slide rest as it was known at a later day by its invention in a practical form by John Maudsley in England, in the year 1794. Whether Maudsley had seen or heard of the invention shown in the French encyclopedia or not, it would seem fair to assume that he must have seen that or something akin to it, as the twenty-two years elapsing between the one date and the other must have served to make the earlier invention comparatively well known in the two nearby countries, both of which contained, even at this early day, many mechanics. It is interesting to observe that the slide rest invented by Maudsley over a hundred years ago has been so little changed by all the improvements since made in this class of machinery.

There seems to have been an early rivalry between the French and English mechanics in the development of machines and methods for advancing the mechanic arts. The next development of the screw-cutting idea seems to have been of French origin. In this lathe there was an arbor upon which threads of different pitches had been cut. These threads were on short sections of the arbor and by its use the different pitches required could be cut. While the exact manner of using this arbor was not described, its probable method of use will readily suggest itself to the mechanic, and was, no doubt, used at an earlier period, and in fact was what led up to the use of a lead screw or arbor with a multiplicity of different pitches. The principle is analogous to that used in the "Fox" brass finishing lathe so well known and extensively used, not only in finishing plain surfaces but in "chasing threads."

This machine is shown in Fig. 10, which is a perspective view giving all the essential parts of the mechanism. The head-stock A and tail-stock B are of the usual form in use at the period, and were mounted upon the wooden bed C in the usual manner. The piece D to be threaded, and an equal length of lead screw or "master screw," as it was then called, were placed end to end in the lathe, the outer ends held in the lathe centers, and their inner ends, evidently fixed to each other by a clutch of some kind, were supported by a kind of center rest F. Fixed to the front of the bed C was a cast iron supporting bar G, of T-shaped section, extending nearly the entire length of the lathe bed. Upon the bar G, the top of which was of dovetail form, was fitted the carriage H, which was adapted to slide upon it and to support a thread-cutting tool J, and a tool or "leader" K, which fitted into the thread of the "master screw" E, and served the same purpose as the lead screw nut of the present day. Evidently the operation was that by revolving the piece D the "master screw" E was also rotated, and this rotation of the threaded screw, acting upon the "leader" K, forced the carriage H forward, causing the thread-cutting tool J to cut a thread upon the piece D, of a pitch equal to that upon the "master screw" E. It is probable that no better means of adjusting the thread-cutting tool J was provided than setting it in by light blows of the hammer. While the threads thus cut were probably rather poor specimens of mechanical work, they answered the requirements of the times, and as usual better means were devised for making them as the need of better and more accurate work created new demands and a higher standard of workmanship.

Fig. 10.   Thread Cutting Machine using a Master Screw.

Fig. 10. - Thread-Cutting Machine using a "Master Screw."

As will be seen in the above example the idea of the slide-rest is used. In this case some such device was a necessity. Doubtless threads had been cut with some sort of a "chaser," or tool with notches shaped to the form and pitch of the thread. These were very extensively used later and for many years in brass work, and the old-time machinist was very expert in their use. The slide-rest, as we know it, while it relieved the workman from the fatigue of holding the tool firmly in his hands and depending entirely upon them for the position of the tool, with the exception of such support as the fixed rest gave him, was comparatively slow in coming into general use. While its usefulness must have been apparent to the average mechanic, the conservative ideas then in vogue must have retarded its prompt adoption, as they did many other meretorious inventions.