This press is also known as the fly press, since adventage is taken of the kinetic energy stored in the rotating mass of the"fly"operating the screw. In fig. 12 is shown the elevation of the frame, together with a part plan and section of the standard. The base B is square in plan, provided with holes for fastening down in place-usually on a bench; the table or upper part is circular in plan, MM is planed or surfaced level, to take the holster or bottom die. When small work is being executed, then a false bottom (fig. 17) is placed in the recess M, which, in its turn, supports the bottom die. The frame is machined to accurately guide in a vertical direction the ram R, which is kept in its place by the strips S. The ram R (which is sometimes culled the holt or slide) carries the upper die at its lower end, and is moved vertically by means of the fly F, fig. 13, which is attached to the upper end of the screw, rig. 14. The screw-works in a nut fitted in the boss H, seen in the upper put of the press frame in fig. 12. The dimensions of the frame will indicate the proportions generally adopted in a tool of this capacity. The screw collar, fig. 18, is screwed on the press screw, fig. 14, being secured by means of a set screw, the lugs A and B being drilled for this purpose. The hole in B is tapped, whilst that in A is drilled slightly larger than the set screw, so that the collar is jammed in any required position by simply tightening up the set screw. This collar, when in position, acts as a stop for the press screw by bumping upon the top of the boss H on the frame, fig. 12. The lower end of the screw, fig. 14, is reduced at D to take the split nut shown in fig. 15. This nut is cut in half along a diameter, so that it can be placed in position; the upper nut, which is large enough to pass over the collar K in the press screw, is then screwed in to hold it in place. In fig. 15 the lock nut is shown screwed on, holding the two halves of the nut in position. The lower part of this nut is then screwed into

Fig. 12.

Fig. 13.

Fig. 14.

Fig. l5.

Fig. 16.

Fig. 17.

Fig. 18.

Fig. 19.

the upper end of the ram R, figs. 12 and 16, and the whole locked together by tightening the lock nut down on the ram.

Fig. 20.

Fig. 21.

FlG. 22.

In the bottom of the hole in the top of the ram, the hardened steel disc B B, fig. 14, is dropped, and this takes the thrust from the lower end of the screw K, which is also hardened. It is called the"bumping bit,"and takes up the thrust of the blow, which might otherwise damage the screw thread of the split nut. The clearance allowed is clearly shown at T in fig. 22; thus the only work that has to be done by the screwed nut is that of lifting the ram and die ready for the next stroke. Connecting the screw to the ram is known as"gartering."

In presses of common make this split nut is cast in malleable iron, which quickly wears away at W, fig. 22, but in first-class work these nuts are made of steel, in the following manner, viz.: A steel forging F, fig. 23, is made both longer and larger in diameter than the actual finished nut. It is then cut through longitudinally (see D, E), after which the faces of each half of the forging are planed perfectly flat, then clamped together, and two holes e, e1 are drilled. The halves are then riveted together, centred, turned, screw cut, a hexagon head milled on, and their ends reduced as shown at b, bl. The nut is then screwed into a special chuck on a lathe. End b is now cut off, and the hole bored. The boring of the hole removes the end b1 This completes the operation. The split nut is now completed by hardening the end B, which is afterwards ground true. At fig. 19 is shown another method of gartering, in which the end of the screw, after being turned parallel, is grooved by a square parting tool, and a ring inserted. This ring is split, so that the two halves may be inserted into the groove. A third method of gartering is shown at figs. 24 and 25, which is the old method for the square ram. After the hole has been bored in the top of the ram, to take the end of the screw, the ram is slotted, to take the two halves of the garter (J, after which two taper key- ways are planed in two opposite sides of the ram,|and into these are driven taper keys, to prevent the garters from slipping back out of place. A modified form of this method of gartering is shown at fig. 26, which is to plane a broad key-way straight across the top of the ram, sliding the two halves into the key-way, and fastening them down by a set pin P.

Fig. 23.

Fig. 24.

Fig. 25.

Fig. 26.

The ram shown at fig. 26 is the shape now used extent sively for the screw press, and when adopted the edges of the garter are planed at an angle, to prevent any great strain coming upon the head of the pin P, to preveut the head being forced off the pin. The ends of the bumping hit. screw, split nut, or ring will, after being sometime in use, wear away. In the case of the gartering methods shown in figs. 19 and 22 the slack or play could he easily taken up or adjusted by screwing the split nut further into the bolt; but in the case of gartering methods shown at figs. 24, 2."). and 26 the slack or play would be taken up by inserting thin sheet steel blanks, as shown in position underneath the humping hit.