META ENG. The accompanying engravings illustrate the most recent forms of metal-working lathe-tools. Fig. 1 shows a lathe threading-tool as made lw the Morse Twist Drill & Co. The holder of this tool is slotted, forming jaws, between winch the circular cutter is firmly livid by a bolt passing through the jaws and the cutter. The cutters are furnished to the V. or U. S. standard thread, singly or in sets, as desired. They are readily re moved from the holder. The roughing cut for a thread may be taken with one section of the cutter and the finishing cut with another, the cutter being re volved in the holder, which need not be removed from the tool-post of the lathe. The cutters are quickly sharpened by grinding the faces. Fig. 2 shows t he Gardner & Woodbridge thread ing tool and holder, together with a series of tools for other purposes t Ilan threading, adapted for the same method of holding and sharpen ing. The holder is made of tool steel, hardened thrcinghout and finished true, giving the same clearance for each tool. The single-point cut ters accompanying are hardened and ground to produce an angle of 60' exactly, with the proper width of flat for the pitch of thread (U. S. standard) that each is intended to cut; simply grinding the top of the cutter parallel with the top of holder when sharpening being all that is required to keep the angle and width of flat at the point correct. The same single-point cut ter is used for right and left hand threads.
3 shows the Woodbridge lathe and plan er tool. The tool is made to shape, thus saving the forging and grindings necessary with or dinary tools. Being supported and backed up close to the cutting-edge, and having no verti cal projection, it will stand heavier cuts and faster feeds than ordinary tools. The new tools can, without alteration of form, be used in a planer as well as in a lathe. If the tools are kept ground in stock. the workman has but is slip in a new tool as the old one becomes dull, no adjustment for height being necessary, as it the forged tool.
Johnson's cutting-off tool, for lathe, planer, and screw machine use, is shown in Fig. 4. The holder in this tool is a plain rectangular piece of machine steel, case-hardened. with recess in side, having the edge beveled to hold blades. which have their edges beveled to correspond to the holder. The small screws at each end are to insure a tight- fit to the blade when in use. and to hold the blade when grinding. This may he used for planer or lathe, work. Fig. 5 shows a boring and inside threading tool. Fig. it shows a lathe-tool, which has but two parts—the holder, which need not be removed from the tool-post, and the cutting-point, which requires only to be placed in position when it is ready for use, its removal being effected by giving the projecting point a slight turn with a wrench.
Fig. 7 shows a new style of center reamer. It is fluted with three cuts, and the emitting edges are relieved. It will in all eases make a round hole, which is not always the ease with the old-style one-cut reamer.
The usual set of tools now used for a turret-lathe is shown in Fig. 8. These consist of one hollow mill and holder and one or two box-tools, one or two die-holders And dies, one cutting off tool, and one stop-gauge.
The shown in Fig. 9, is designed for checking cylindrical pieces that they may be held firmly by hand. The holder is jointed, that the knurls may center themselves, and be used in a weighted lathe without an extra weight being applied to the carriage to hold it in position.
Cast-Iron L«Ile-Tools.—Cast-iron tools for cutting metals have been successfully used in the Pennsylvania Railroad shops at Altoona, and in the shops of the Ferracute Nachine at Bridgeton, N. J. They are made to the ordinary standard Shapes used for forged tools, as shown in the accompanying diagrams (Figs. 10 and 11). which are copied from those used in the Altoona shops. The names, functions, and dimensions corresponding to the numbers are given in the following For it given size of cut, the shank of one of these tools should he somewhat larger than in the ease of n forging, in order to give the required lateral strength where it is fastened in the litherwise the shapes and sizes may be exactly the same. In general, heavier cuts and proliahly somewhat, higher speeds can he taken with these tools than with forged steel urs, fur the reason that there is no Clangor of drawing, temper by the heat due to friet ion. The experience of the Pennsylvania Railroad Co. shows that, on the whole, these tools, cheaply made as they can he, are superior to steel tools for roughing-ents, but that they lire not desirable for finishing-cuts.
The construction of these tools is of the simplest description. An ordinary wooden pat tern of the exact shape desired is molded in the usual Way, with a small portion of its cutting point in a cast-iron chill. A tool can not, of course, be repaired in the blacksmith-shop, but must be melted up when worn out. They can be so cheaply recast that their maintenance, as well as their original cost, is much less than that of the ordinary forgings. The best com position of metal, as far as has been ascertained, is the same as for car-wheels, and no partic ular care is necessary in regard to the method of pouring or the heat of the melted metal.
see Mills, Silver.