direction in the piece, and all are drilled simultaneously, or in the time occupied in drilling one hole. Horizontal and vertical boring machines are used, not only for drilling large holes, but for boring out cylinders and other like castings requiring large and heavy boring work.

Ninth. Grinding. Great accuracy, efficiency, and economy have been realized in the use of grinding operations. This work may be divided into three classes: (a) cylindrical grinding; (b) surface grinding; and (c) disk grinding. In the first the piece is usually placed on centers, and revolves in the opposite direction to the grinding wheel. In the second the work, or the wheel, travels to and fro on a table similar to a planer table, while the wheel revolves above it and is gradually moved across it. Disk grinding is a kind of surface grinding, but is mainly used for the purpose of finishing or polishing the surface of machine parts having flat surfaces. In this form the grinding surfaces are composed of flat cast iron disks whose surfaces are cut with a shallow spiral line. The surface is covered with emery cloth cemented to it. The work to be ground is laid upon a table normally located at right angles to the face of the disk, but capable of being adjusted to any desired angle when angular surfaces are to be finished. Two of these disks arranged facing each other, and one of them made adjustable, are used for grinding opposite surfaces of flat pieces.

Improving the Design of Machines. The comparatively recent advent of "high-speed tool steel" and its ability to stand very high speeds, largely increased feeds, and heavy cuts, brought about conditions which called for much heavier and stronger machines. These the manufacturers at once began to design and build. But there remained many machines of the older, lighter, and less powerful types still in the shops. These were usually in good and serviceable condition, except as above stated. It therefore became an engineering problem to re-design, re-build, or strengthen these machines so as properly to fit them for the increased service demanded of them. The following is a simple example of how this work was accomplished.

In carrying out these improvements the process need not necessarily be an expensive one. The improvement should only be undertaken after a thorough examination of the machine and the work that is to be done upon it, by a competent and practical man, well versed in this particular class of work, and the expense of whose services will frequently be saved in the economy of the work of reconstruction.

A case in point is that of an eight-foot vertical boring mill of old design and construction, as shown in Fig. 209, which was required to do heavier and faster work than it was designed to do. The problem was to bring it up as near the capacity of a modern machine as possible. Upon examination it was found that the cross rail, saddle, and boring bar parts and the

supporting side posts were quite sufficient for a considerably increased duty. The driving mechanism, however, was weak and not sufficiently strong for heavy cuts or the fast feeds made possible by the use of high-speed tools. While the table support was not as rigid as could be wished for, it was decided not to spend any money on that feature, as the work it was to do did not require extreme accuracy.

The driving mechanism at A, Fig. 209, was constructed substantially like a back-geared lathe head attached to a suitable projection on the base of the machine, and whose main spindle reached to the edge of the circular table, and had fixed upon it a bevel pinion engaging a large bevel gear fixed

FIG. 209. Increasing the Efficiency of a Vertical Boring Mill.

to the bottom of the revolving table, as shown at B. This mechanism consisted of face gears 22 inches, and the back gears 2-inch face, with a fivestep cone of 31-inch face. In re-designing this feature the face gears were made 31-inch face and the back gears 3-inch face. The driving cone was made with three steps only, instead of five, thereby permitting the faces to be 5 inches wide, as shown at C. The driving bevel pinion at B was of proportionately large pitch, but was made of cast iron. To gain sufficient strength it was replaced by one of steel.

By this simple arrangement the power and cutting capacity of the machine was increased over 50 per cent, while the increase of speed was gained by changing one overhead pulley. Its working capacity could be still further increased by the addition of another tool holding head. Thus the first and second methods were realized in this machine.

Another method of increasing the efficiency of a machine by the addition of devices and attachments is more applicable when the work of the machine is a regular line of similar pieces. Special devices may be made for holding the work, so as to secure greater rigidity and to reduce the time required for putting in and taking out the piece of work.

Other devices may be made for better securing the cutting tools, or for using a greater number of them. For instance, in turning cone pulleys, the ordinary lathe tool block carries but one or, at most, two tools, while it is a comparatively simple and economical matter to construct a tool block carrying as many tools as there are steps to the cone, and turning all of them at once. A taper attachment will permit the pulley faces to be properly crowned. This suggests a wide field for interesting study and is well worth the best work that can be applied to it, and the devices that may be designed for almost any kind of product are numerous and valuable if carefully worked out by men who are well versed in this class of work.

Still another method, that of providing better tools, is a more simple question. If the tools are made of the ordinary grades of tool steel much greater efficiency can be realized by the use of high-speed steel. Its cost may be five or six times that of the ordinary tool steel, but this should not prevent its use, since it will be exceedingly economical in any event. The tool steel expense may be kept within reasonable limits by the use of tool holders for lathes, planers, and similar machines, as they will require only short pieces of small square steel as cutters, instead of the cutting portions. being forged upon the end of a bar weighing many times as much. However, for heavy and rough work a solid tool is preferred by many good shop men on account of its great rigidity.

In the use of solid tools, the efficiency of the machine will be much affected by the form of the cutting portion of the tool. This will include not only the form given it by the tool forger, but the angles to which it is ground. To insure the proper treatment of the tool in this respect a good tool grinding machine should be used. This machine should be so constructed that tools may be rigidly held at the various angles required (which should be shown on an index), and uniformly and quickly ground.

This machine should be located in the tool room, and all tools requiring to be ground should be sent there and exchanged for like tools properly ground and held in stock ready for issue. This exchange should be made by errand boys, who should keep the operators supplied with sharp tools. Operators at the machines should not be allowed to grind tools except in rare cases and by order of the foreman.

The arrangement of machines with relation to each other and the transportation facilities necessary to serve them in an efficient manner is a problem

that is not often satisfactorily solved. Here again the particular nature of the product to be turned out must be taken into consideration and the requirements carefully considered and worked out in accordance therewith. The product might be large and heavy engine work, which would require a certain arrangement of machine in order efficiently and economically to carry the parts through the works. Or, it might be machines composed of many comparatively light and easily handled parts, which would necessitate quite a different array of machines and located upon an entirely different plan. Thus we see that the nature of the product will govern, not only the selection of proper machines, but the location of these machines in relation to each other. Necessarily this latter condition will decide the character and location of the transportation facilities necessary.

A specific example will be given from which general principles may be deduced that may be applied to other and quite dissimilar cases.

Fig. 210 shows the original arrangement of the machines in a department in a manufacturing concern, in which there was a large volume of heavy

planing. In the bay at the right of the plan was a group of large planers, while those of medium size were located at the rear of the main room, and a single small one at A in the bay at the left of the engraving. The main group of lathes were placed along the front of the main room, with a section of small ones along the outer or street wall as shown. There was a medium-sized lathe at B, and a heavy 68-inch swing lathe at C. Also a chucking lathe at D, near the right part of the engraving. In the main

room were two upright drills near the door N, and along the rear wall near the small planers a polishing head at E, a polishing belt at F, and an old-time suspension drill at G. Near the group of small lathes there was a sensitive drill at H, a slotter at J, a bolt cutter at L, and a horizontal hydraulic press at M. It will thus be seen that many of the machines were apparently located at random and with little regard for any definite plan as to their uses or the progress of the work.

In the operation of the shop, castings were received at N, the heavier ones put on trucks and taken to the group of large planers, many of them brought back to the upright drills, near the door N, some taken to the 68inch lathe at C, and then back near the group of large planers to be erected. Forgings came in through the door at P, went to the planers in the main room, the lathes opposite them, or those in the left bay, then to the hydraulic press for force fits, then back to the erecting floor at the opposite end of the department.

Face plates were roughed off on the large planers, carried to 68-inch lathes at C to be turned, and, after a more or less wandering career, finally arrived at the erecting floor. Dirt and dust from the polishing head at E and the belt at F was quite injurious to the machines in the vicinity. Transportation facilities were crude and the continual moving of material and work in progress back and forth was not only expensive, but kept the main passage in the center of the room in a constant state of congestion and blockade much of the time.

The plan for re-arranging the shop is shown in Fig. 211, and was as follows: The group of large planers, those along the rear walls of the main room and the group of large lathes opposite to them were not disturbed. The other machines were moved to the locations shown. The left bay was practically cleared of machines and made an erecting floor, the lathe B being retained for convenience of small jobs during the erecting work. The group of lathes were eliminated altogether as they were no longer needed. A polishing room was built and the machines E and F placed in it, thus confining the dust and dirt nuisance in a small space. An overhead traveling crane was set up covering the entire space of this bay, giving great convenience for the erecting of machines. A small tool room was built and in it was placed a tool grinder Q and a twist drill grinder R. A door for the receipt of castings at S, and a floor scale were put in. Shop tracks were laid as shown running from the door S, across the scale and on to the group of large planers at the rear; also, through the center of the main room, from the doors P to N, with a turntable at the intersection of these tracks. Branch tracks run through the center of the erecting floor to the door X.

The planer A, formerly in the left bay, was added to the group of planers