LXII. On making solid and hollow Screws, for Vices, Presses, Waggon-jacks, &c. By the EDITOR.

WE think it desirable, in addition to what we have given in the articles on screw-making, contained in our present number, to afford our readers a description of the singular methods employed by the standing vice-makers, and which we believe are peculiar to them, as we have not seen them practised by any other workmen.

Our knowledge is derived from witnessing the practices of a branch of the family of the Wright's, settled at Birmingham many years since; the original seat of their business being at Dudley, in Worcestershire, where their name has long been celebrated for the superior excellence

of their articles.

The solid screws are made of the very best scrap iron, and which, of course, is of a high price, as nothing but an excellent quality of iron could possibly endure the severity it is subjected to, in bringing up the square threads of the screws in the manner we shall presently describe.

The iron cylinder for the screw being carefully forged, it is firmly held upright between the chaps of a stout screw clamp, affixed into a wooden post, secured in the earth, and the square hardened steel block, which contains the screwed hole, to form the threads of the screw, is held in a square hole, made in the central part of a stout iron lever, fifteen feet in length, and where it is firmly secured by binding-screws. The iron cylinder to form the screw is rather less in diameter than the tops of the threads of the screw, so that the threads are partly indented, and partly squeezed up by the action of the hollow screw in the block upon the iron, it having no cutting action. The lever is actuated by one or more persons at each end of it, according to the size of the screw, and who alternately advance and recede by degrees, in their progress of forming the screw; frequently also applying oil to the top of the hollow screw as they proceed, to ease the labour in some degree, which

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however is very considerable, as we may well believe. In consequence of the great condensation of the iron, effected by this process, these vice and other screws acquire that hardness and great durability which they are well known to possess.

We are not acquainted with the means by which the vice-makers originally formed the hollow screws in their steel blocks; but there can now be no difficulty of effecting that operation.

The threads being thus produced around the solid screws, in order to form the hollow screws, or boxes, as they are termed, the following methods are employed :-A rod of iron is carefully forged, so as to fit and fill up the groove between the threads, but rather broader, so as to extend a little above their tops, when coiled around the screw. This coil is then enclosed within a wrought-iron cylindrical case, formed of a plate of iron turned up around the coil, till the edges of it meet. A flat web or wing of iron is then placed along the joint, and another upon the opposite side of the box, and both are then secured in their places by hoops or bands of iron driven tight over them. These webs are intended to prevent the box from turning round in the cheeks of the vice, or in the holes made to receive it, in the frames of the presses, &c., for which they are intended. And, in the case of making a vice-box, a knob of iron is also fitted into one of the ends of it, and an iron ring, larger than the box, affixed upon it. All being thus adjusted, in order to unite and combine the whole together firmly, the process of brazing or soldering is resorted to as follows:

Slips of old brass are laid along the inside of the box, and others are also placed on its outside, and the whole is carefully enclosed within a casing of plastic clay, which is wrapped around it, avoiding however to touch the parts which are to be soldered together; a small hole is also formed through the clay, at the open end of the box; but all the other parts are accurately closed up. This encasing

of clay is then dried a little, by placing it in the vicinity of the forge fire, and, finally, it is laid in the fire itself, which is urged by blowing, until the fumes of the zinc in the melted brass are seen to escape through the hole in the clay, which is left as above mentioned, and intended for this purpose; the mass ought also to be occasionally turned whilst lying in the fire, in order to heat it uniformly. When the fumes of the zinc appear, the box is to be removed from the fire and laid upon the earth, where it is to be kept continually rolling backwards and forwards for some time, in order to diffuse the melted brass uniformly among the parts to be united by its means; it is then left to become cold, when the crust of clay is to be broken off, and the iron hoops removed. The box is now ready to have the screw fitted into it, and which is effected by placing it in a vice, and working the screw backwards and forwards in it, by means of a lever, placed in the hole formed in its head, and at the same time applying sand and water, to assist it by grinding, to make its way through the threads in the box, but which sand must afterwards be carefully washed out again.

We do not know whether or not borax is used in this soldering process; at any rate, it would conduce to its efficacy.

We may add that locksmiths use a similar process for soldering the boxes of wards in locks; sometimes, however, wrapping a sheet of thick paper around them to prevent the clay from entering them.

It is evident that a box, or hollow screw for the large screw, the construction of which forms an article in our present number, might be made in the above manner. We also think that a hollow screw might be cast around the screw, in brass or gun-metal, by surrounding it with a proper casing, and having previously coated the screw with pipe clay, to prevent the melted brass from coming into contact with it.

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LXIII.—On making Springs of hammered Iron. By the EDITOR.

THE Editor was lately shown an improved lock, made by an ingenious frame-smith, from Nottingham, and in which were a number of tumblers, actuated by means of springs. On the editor objecting to the employment of so many springs, lest some of them might fail, he said that could hardly happen, for they were made of hammered hoop-iron, which endured much longer than hardened and tempered steel springs!

We state the fact as it occurred. It was new to us, but may be commonly employed in Nottingham, where so much excellent work is done, in making the stocking-frames, bobbin-net lace machines, &c. &c., and we have no doubt that the very slender iron rods or plates, which are employed so largely in the latter machines, are also stiffened, and greatly improved by hammer-hardening them.

The hoop-iron is now greatly used for many other purposes than that for which it was originally intended, on account of its superior quality; and it no doubt forms an excellent material for the use of the frame-smith.

We communicate this fact, in the hope of rendering it available in other branches of business, as it is only from the judicious combination of the various methods employed in different manufactures, that any real improvements can now be expected to arise.

LXIV.—On an improved mode of making Screw Tools, for cutting hollow screws flying in the lathe. By the late Mr. ANDREW FLINT, Engineer.

WITH FIGURES.

Mr. FLINT was rewarded, many years since, by the Society for the Encouragement of Arts, Manufactures, and Commerce, for two differently constructed expanding band

wheels or riggers, of his invention, and which well deserve to be brought into general use at the present time. He was also the patentee of a rotatory steam-engine, and indeed was an excellent mechanic.

Having found that the tools for cutting hollow screws in the lathe, or flying, as it is termed, had the ill effect of lessening the depth of the threads, owing to the improper manner in which the tools are usually made, by holding them sideways against a cutting-screw, actuated by the lathe, in the same manner as is used in forming the ends of the tools for cutting solid screws flying, and whereby their teeth are crossed, or inclined in the wrong direction for cutting hollow screws, and thus, as above mentioned, they lessened the depth of the screws cut by them. Now, in order to avoid this evil, he partly enclosed the piece of steel intended to form the screw-tool, within a thick plate of iron, bent over the back of it, and bringing its edges even with the intended edge of the screw-tool, he filed the whole into a portion of a cylinder, capable of being received within the dies of a screw-stock, and of being acted upon by them, so as to cut the teeth on the edge of the tool, in a fit and proper manner to act as a screw-tool, in cutting hollow screws in the lathe flying.

In plate V. fig. 19 represents a top view of part of such a screw-tool; and fig. 20, an end view of it. Fig. 21 shows the tool as partly surrounded by its iron casing, and as having been acted upon by the screw dies, as above mentioned; the dotted circles surrounding it may either represent the depth of the threads of the screw, or that of the hollow screw to be cut by the tool in the lathe, after being, of course, divested of its iron back, and hardened; and when it is to be held upon the lathe rest, in exactly a similar position with respect to the hollow cylinder to that here shown.

It is evident that such a screw-tool will turn or cut a hollow screw in the lathe, as deep as the threads of the original screw which formed the dies. But should its edge

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