Chapter IV: Machines and Tools for Shrapnel Manufacture (1)

=Reed-Prentice Co. Equipment for Machining Forged Shrapnel Shells.=--In machining the 18-pound British shrapnel shell on the equipment furnished by the Reed-Prentice Co., Worcester, Mass., eight distinct operations are performed as follows: First, drilling a center hole in the closed end of the forging in a Prentice 16-inch ball-bearing sensitive drilling machine equipped with a special centering fixture; second, rough-turning the outside diameter, grooving, squaring the closed end and rounding the corners in a Reed-Prentice 14-inch heavy type automatic lathe; third, machining the powder pocket and diaphragm seat, as well as the internal and external diameters of the nose in a 14-inch Reed extra-heavy turret lathe; fourth, under-cutting band grooves and producing wave ribs in a 14-inch Reed engine lathe; fifth, boring, reaming, threading and facing the open end in a Reed 14-inch extra-heavy turret lathe; sixth, finish-turning outside diameter and radius on nose, also form-turning copper band in a Reed 14-inch heavy type automatic lathe; seventh, cutting off center projection on closed end of shell in a Reed 14-inch engine lathe; eighth, finishing brass socket to form, cleaning inside of socket and cutting off excess length of tube in a Reed 14-inch extra-heavy turning lathe.

=First Operation on Rough Shell Forging.=--The drilling of the center hole in the closed end of the forging is a comparatively simple operation, and is performed in an interesting fixture held on a 16-inch Prentice ball-bearing sensitive drilling machine. This fixture, which is designed for handling the work quickly, is shown in Fig. 1, and consists of the base casting _A_ clamped to the table of the drilling machine. The entire back part of the jig swings on the trunnion _B_ to provide a means for quickly removing the forging _C_ from the arbor _D_. A locking-pin _E_ is used for locating the fixture in its upright position for drilling. Bushing _G_ in the top plate _F_ of the fixture guides the combination drill and countersink.

The construction of the work-holding arbor is worthy of special attention. This arbor _D_ has a cap _H_ on its top end that acts as a stop for the inside of the forging, which, in being placed over the arbor, is located centrally and clamped by fingers _N_. To operate these fingers, hand lever _I_ is depressed, and as this is fulcrumed at the point _J_, it causes collar _K_ to rise on the arbor. Yoke _L_ forms a connection between the lever and the collar with which the sleeve carrying fingers _N_ is integral. Fingers _N_ are fulcrumed in arbor _D_ and are thrown outward to grip the forging when sleeve _M_ is raised. Light springs _O_ tend to keep the gripping fingers in a vertical position against the arbor when they are not being forced outward by the inclined surfaces on sleeve _M_. Handle _I_ carries a spring pawl _P_ that holds the sleeve _M_ stationary while the forging is being center-drilled.

=Second or Rough-turning and Facing Operations.=--The second operation is performed on a Reed-Prentice 14-inch heavy type automatic lathe, as shown in Figs. 2 and 3. The forging _A_ is held on an internal expanding arbor _B_, the driving part of which is supported by the head-center. At the closed end, the shell is steadied by the tail-center. The bottom of the shell rests against the end of the arbor which acts as a gage. In this setting, the external diameter of the forging is rough-turned by four tools _F_, mounted on the carriage _G_. This carriage has a travel slightly less than two inches, and an automatic throw-off is provided at the end of the cut that disengages the tools, draws them back and returns the carriage. At the rear of the carriage on this machine a facing arm is mounted on a heavy bar. Turning tools are carried on this facing arm, as shown, and when the front carriage feeds longitudinally a cam bracket _O_, bolted to the carriage, is carried along with it. Clamped on this bracket is an adjustable cam _N_ held in place by screws. Cam roll _M_ on the facing arm contacts with cam _N_, causing the facing arm to rock forward as the carriage travels longitudinally.

Referring to the plan view in Fig. 2, tool _H_, held in the arm, faces the end of the forging, tool _I_ chamfers the corner, and tool _J_ cuts the depression for the wave ribs, leaving a projection in the center from which the ribs are formed. It should be understood that the tools on the carriage and facing arm work together. One man can run two of these machines without trouble.

=Third Series of Machining Operations.=--The third series of operations on the shrapnel forging is performed on a 14-inch Reed heavy lathe with a specially large turret, as shown in Fig. 4. This lathe is fitted with a 12-inch three-jaw chuck, bored out to 3¹⁄₂ inches to permit the forging to extend into it. The forging _A_ is put in the chuck as shown at _B_, and the jaws grip at _C_. The first operation is performed with a bar _D_ carrying a blade cutter _E_ that rough-bores the powder pocket, and tool _F_ that rough-bores the mouth. The turret is now indexed, and a boring-bar carrying a blade _G_ roughs out the diaphragm seat, while an auxiliary tool _H_ faces the shell to length. At the next indexing of the turret the boring-bar _I_ that carries the finishing tool _J_ finishes the diaphragm seat and powder chamber.

=Fourth Operation--Under-cutting and “Waving” Band Groove.=--For the fourth operation, the forging is held in a 14-inch Reed engine lathe provided with an automatic attachment for under-cutting and waving the ribs for the copper band. The tool equipment used is shown in Fig. 5, where _A_ is the forging held by one end in the chuck and supported on the opposite end by the tail-center. The tools are all located in holders on the heavy base block _B_, and their operation is controlled from the carriage _R_ of the lathe. The cutting of the wave ribs is done by tool _C_ at the front, held on a slide that operates on the top of block _B_. Spring _D_ keeps the roll _E_ on the lower slide of the tool-holder in contact with the cam slot in cam-plate _F_ that is fastened to carriage _R_. When the carriage is traversed toward the chuck, the irregular surface of cam-plate _F_ engages the roll and forces the tool-holder forward. Side motion to produce the wave is then effected by face-cam _G_, mounted on the chuck and contacting with the roll _H_. This roll is supported on a bracket forming an auxiliary slide _S_ that carries the waving tool _C_. A stiff barrel spring keeps slide _S_ in contact with the cam _G_. Thus, when the machine spindle revolves, the auxiliary slide is caused to oscillate back and forth far enough to give the desired amount of wave.

The under-cutting in the band groove is accomplished by tools _I_ and _J_ which are mounted on separate tool-slides _K_ and _L_. These slides are fed in at an angle to the axis of the forging, against the action of coil springs _M_ and _N_, by the cam surfaces of plate _Q_ in which rolls _O_ and _P_ work. Plate _Q_ is bolted to carriage _R_ which, in advancing toward the chuck, forces in the under-cutting tools in the manner just described. The tail-center of this machine is fitted with a quick-acting mechanism so that it may be withdrawn quickly to insert a new piece.

=Fifth Series of Operations.=--Before performing the fifth series of operations, the forging is heated and closed in on the nose. It is then handled in the following manner: A Reed 14-inch heavy lathe, equipped with an extra large turret mounted on a special wide-bridge carriage carries tools for boring, reaming, threading and final squaring of the open end, as shown in Fig. 6. The shell forging for these operations is held in a three-jaw chuck provided with special jaws. In the first position the rough-boring of the nose and the rough-facing of the extreme end is performed with tools _B_ and _C_. The turret is then indexed and tools _D_ and _E_ finish-ream the hole in the nose and face the end. The tap _F_ is next brought into position, cutting the thread in the nose.

The turret is again indexed, bringing a special form boring tool into position. Here the boring tool _G_ is carried in a bar _H_ held in a holder of the cross-sliding carriage type that is fastened to two faces of the turret. By means of cross-screw _J_, the boring tool _H_ may be drawn in or out at will. This tool operates as follows: As the turret is advanced, handle _J_ is operated to let tool _G_ enter the nose of the shell, and, upon the continued advance of the turret, arrow head _M_ is forced in between and gripped by the fingers _N_. The turret is now backed away from the chuck, and while receding acts upon slide _P_ through the medium of roll _L_ and cam groove _R_. The plate containing cam groove _R_ is attached to the arrow head _M_ and consequently is held stationary while the turret is being withdrawn from the work. This backward movement of the turret is continued until the tool _G_ is withdrawn from the work and slide _S_ comes in contact with check-nuts on rod _O_, withdrawing arrow head _M_ from fingers _N_ and allowing the turret to be indexed ready for the first operation on the next forging.

=Sixth or Finish-turning Operations.=--The sixth series of operations is performed on a Reed-Prentice 14-inch heavy type automatic lathe, similar to that used for the second operation, and the machine is also operated in a manner similar to that previously described. The operations consist in finish-turning the outside diameter of the shell and turning the radius on the nose. In addition, the copper rifling band, put on previous to this operation, is turned to shape. Referring to Fig. 7, the shrapnel shell _A_ is held by the tail-center at one end and is supported and driven from the other end by a plug screwed into it. This plug is held on the live center and is driven by an equalizing driver, coming in contact with pins in the special faceplate.

Two slides _B_ and _C_ are carried on the front of the carriage. Slide _C_ carries three tools _D_; two of these start in from the rifling band and turn in toward the nose, and the other works up toward the rifling band from the closed end. Tool _E_, carried in slide _B_, turns the curve on the nose of the shell and is controlled in its action by means of a slot in cam _F_ in which a roller held to the slide operates. At the rear of the carriage is carried a facing bar attachment, as previously described in connection with the second operation. This attachment carries three tools, as illustrated, for machining the rifling band to shape, facing the closed end and chamfering the corner.

=Seventh and Eighth Operations.=--After the sixth operation, the fuse tube is threaded into the diaphragm, the bullets put in, and the hot resin poured in to keep them from rattling. The brass socket is then screwed into the nose and the fuse tube soldered to it. The shell is now ready for the seventh operation which consists in cutting off the center projection. This is accomplished in a Reed 14-inch engine lathe, provided with a faceplate chuck for holding and driving the shell at the open end, and a steadyrest for supporting it close to the point where the cutting is being done. The shell is now ready for the eighth operation, which consists in machining the brass socket to shape in an extra-heavy lathe as shown in Fig. 8. The tools used for machining are retained in a special holder on the carriage. Tool _A_, which is used for facing off the fuse tube and the brass socket, is inverted, starts at the center and is fed out toward the circumference. The external surface of the socket is machined with a circular forming tool _C_ held on a stud _D_ located in block _B_. The inward travel of this tool is limited by stop _E_ coming in contact with the shell.

=Making Shrapnel Shells on the Cleveland Automatic.=--An unusual example of automatic machine work is that of producing the shrapnel shell shown in Fig. 9. This shell is made from a bar of 3¹⁄₁₆ inch chrome-nickel steel stock. The steel has a tensile strength varying from 125,000 to 135,000 pounds per square inch, and is extremely tough. The work is accomplished on a 3¹⁄₄-inch Cleveland automatic, and the tooling equipment, as shown in Figs. 10, 11, and 12, is interesting. While the general operation of the Cleveland automatic is well understood by many mechanics, the production of this piece illustrates a number of points in the operation of this machine which are not so well known. Therefore, it is advisable to explain in detail just how this interesting job is handled.

The first operation, as the job was originally laid out, was to feed the stock out to the stop _A_, shown in Fig. 11, which is held on the cross-slide and operated by a lever on the base of the machine. This method has been improved upon since the photograph shown in Fig. 11 was taken, and the time reduced from twenty-seven and one-half minutes to twenty-five minutes (see Fig. 10 for improved method). The second operation is to rough-drill the large hole with an inserted bit _B_, step the hole for the taper reamer with cutter _C_ and rough-turn the external diameter with cutter _D_ held in a special turning attachment. This attachment envelops the shanks of all six tools in the turret in order to obtain support. The cutters in the attachment shown in Fig. 11 work in advance of the under-cutting forming tool _E_ shown in Fig. 12, which is held on the rear cross-slide. The time required for the completion of the operations outlined is thirteen minutes.

In the third operation drill _H_ finishes the powder pocket, and two cutters _I_ counterbore for the tap--time required three minutes. The fourth operation consists in finishing the diaphragm seat with the counterbore _J_, finishing the front end with inserted cutter _K_ and breaking the corner to facilitate tapping with inserted cutter _L_, the time required being forty-five seconds. In the fifth operation the thread is cut with a tap _M_ held in the tap-holder _N_ in forty-five seconds. Then the turret is indexed and for the sixth operation the hole is taper-reamed with reamer _O_, provided with four inserted “Novo” steel blades, in ninety seconds. The last and seventh operation consists in knurling the band with a knurl _P_ (see Fig. 12) mounted on the front cross-slide, and cutting off the shell with a cut-off blade _Q_ retained in a holder on the rear cross-slide--time six minutes. The total time required to produce this shrapnel case by the improved methods illustrated by the diagram in Fig. 10 is twenty-five minutes.

There are several points of unusual interest in the production of this shrapnel case. One is the large amount of stock to be removed to form the hole; the second is the long taper-reaming operation--difficult work to accomplish satisfactorily on an automatic screw machine--and the third is the long outside forming operation which must be held to a limit of 0.0005 inch on the diameter. In order to accomplish this last operation successfully, the external diameter of the piece is first turned with a cutter held in a separate turning attachment, leaving only 0.010 inch on the diameter to be removed by a wide under-cutting or shaving tool _E_ held very rigidly on the rear cross-slide. Not only must the case be exact as regards diameter, but it must not vary from one end to the other nor at any point throughout its length. The large shaving tool held rigidly in the manner illustrated in Fig. 12 accomplishes this result satisfactorily.

The material from which the case is made is so tough that some difficulty was met with in selecting a tool steel that would stand up for a reasonable length of time under cut. The drills and counterbores are tipped with “Novo” cutters and all the forming tools, including the cut-off tool, are also made from the same steel. The only cutting tool in the entire tooling equipment not made of this steel is the tap. The bar is rotated at sixty-four revolutions per minute, giving a surface speed for the external cutting tools of approximately fifty-one surface feet per minute.

=Machining the British Forged Shell on Potter & Johnston Automatics.=--In making the British forged shell on the Potter & Johnston automatic chucking and turning machine, three operations complete the work. The first operation completes the outside of the shell, except for the extreme end which is covered by the gripping mechanism of the chuck. The second operation finishes the inside of the shell and at the same time finish-turns the extreme open end. After the second operation is performed the shell is “nosed,” which consists in heating it in a lead bath and then striking it under a light press to close in the end. The third operation then follows, and consists in taking light cuts from the inside diameter and threading the open end of the shell.

=Method of Holding Shell for First Operation.=--For the first operation, the shell is held on an expanding arbor of the type shown in Fig. 14. The arbor _A_ is tapered on its rear end and is held in the nose of the spindle of the machine. The shell is pushed onto this arbor until the end of the arbor strikes the bottom of the shell. The gripping mechanism which comprises six jaws _B_ and a draw-in plunger _C_ is contained inside the arbor. The external diameter of the arbor is machined to practically the same shape as the internal diameter of the shell, but is smaller. The jaws are held in slots which control their movement in every direction except radially. They are forced out radially by means of the draw-in bar _C_ which is provided with tapered seats that engage the inward end of the jaws. The bar _C_ is operated by a hand lever _D_ that extends up over the top of the machine, is fulcrumed in a bracket on the rear bearing cap, and is connected to a sliding sleeve _E_.

In clamping the work on the arbor, lever _D_ is lifted up, this action drawing the sliding collar _E_ to the right along the sleeve _F_, which, in turn, allows the forward end of the fingers _G_ to close in. This releases the pressure of the outer end of the fingers on the draw-in bar _C_. When the pressure from bar _C_ is released by means of handle _D_, heavy coil springs _H_ then come into action forcing the draw-in bar back and expanding the clamping jaws. Additional clamping means are provided by three set-screws which are brought to bear on the work after it has been clamped in position by the jaws. To release the work, the reverse action takes place, that is, lever _D_ is forced down which slides the collar _E_ to the left, operating the fingers _G_, which, in turn, overcome the pressure of the springs _H_, allowing the clamping jaws _B_ to collapse.

=First Machining Operation Set-up.=--The order of the first series of operations in machining a forged shrapnel shell is as follows: First, rough-turn 7 inches along body of shell, face end and chamfer; second, finish-turn 2¹⁄₂ inches along shell; third, rough-groove for copper band and dovetail; fourth, turn waves in groove.

For the first operation, the work is held on the expanding arbor shown in Fig. 14, and the tool equipment, which is of an unusually interesting character, is shown in Fig. 15. The first rough-turning operation, accomplished by turret tool _A_, which is of the relieving type to be described later, is held on the first face of the turret and roughs down the body of the shell. On the opposite side of the holder is a roller support _B_ which supports the shell while the turning tool is in operation. The end of the shell is faced by means of a facing tool _C_ which is really a type of facing mill. The end of the shell is then chamfered by means of a chamfering tool _D_ that removes the sharp corner.

After these operations have been performed, the turret is indexed and the second face of the turret is brought in line with the chuck. This operation is accomplished with a relieving tool-holder _E_ carrying a cutter _e_, which takes a cut 2¹⁄₂ inches along the body of the shell. An interesting feature of this tool is that on the return stroke of the turret it swivels back out of the way so that the shell is not scored by the tool dragging over it. The construction of this tool is more clearly shown in Fig. 16.

As is clearly shown in this illustration, the turret relieving turning tool comprises a shank on which is fulcrumed a tool-holding member _B_. This is slotted out to carry the turning tool _C_ which is clamped in place by two set-screws _D_ and is adjusted to turn the correct diameter by means of an adjusting stud and clamping nut _F_ and _G_. The method of operating this tool is as follows: The fulcrumed tool-holder _B_ is “held up” by means of a fillister-head screw, screwed into a stud _H_ and acted upon by a coil spring _I_. A hole to receive the stud is drilled in the tool-holder _B_, allowing about ¹⁄₁₆ inch clearance. When the tool is in action it has a reverse position to that shown in the illustration, that is, the turning tool instead of being parallel with the center line is at a slight angle with it. In action, as soon as the turret advances, the tool comes into contact with the work, and the work, turning around, forces the cutting tool down and consequently depresses the spring, at the same time bringing the “lower part” of the hole into contact with the extended plug on the holder. In this way the tool is held rigidly and in contact with the work. As soon as the turret begins to move back, however, and the cutting pressure is released, the spring comes into action and throws up the tool, bringing it out of contact with the work.

Upon the completion of the operation which is accomplished from the second turret face, the turret is again indexed and the next operation is performed from the rear cross-slide and the third turret face. The third operation consists in cutting the grooves for the rifling band, and, on account of the under-cutting necessary, involves some interesting points. In order to hold the work rigidly while the grooving tools are acting on it, a revolving support _F_ is brought in from the turret. The wide tool _G_ for cutting the band grooves (this tool removes the greatest amount of the stock) is held on the rear cross-slide and is of the under-cutting type; that is to say, it operates under the work or tangentially instead of radially. Held on a bracket on the third turret face are two tools _H_ and _I_, the purpose of which is to dovetail the rifling band grooves. These turret tools are held in a holder working in a slide on the bracket fastened to the turret face and are operated by a block held on the rear cross-slide. The action of these three tools, therefore, is simultaneous. The wide grooving tool, however, is slightly ahead of the dovetailing tools.

The last operation is accomplished when the turret is indexed to the fourth position. Here, again, a roller support _J_ steadies the work while the waving tool is in action on it. The two waves that are formed are for the purpose of preventing the rifling ring from turning, and they deviate about ¹⁄₁₆ inch laterally from being a true annular rib. The tool for cutting these ribs is shown at _K_ and is of the forming type held in a dovetailed groove in the holder _L_. This also carries a roll _M_ which contacts with the waved surface of the face-cam _N_, the curve of which gives the correct out-and-in motions to the waving tool _K_. The cam face is on a sleeve that is threaded onto the nose of the spindle of the machine, as is shown to the left of the illustration opposite the first turret face.

=Method of Holding Shell for Second Operation.=--The second series of operations on the shell is also performed on the Potter & Johnston automatic chucking and turning machine. The shell is held at the base end by a special collet of the draw-in type, as shown in Fig. 17. Fixed in the nose of the spindle is a positive stop _A_ against which the shell is held by means of the draw-in collet _B_. This collet extends into the draw-in rod _C_, to which it is attached. The method of operating this gripping mechanism differs slightly from that shown in Fig. 14. In this case the spring collet _B_ is drawn into a tapered sleeve to clamp it on the work. This is effected by means of lever _D_ which is fulcrumed in a bracket extending from the rear bearing cap of the machine and operates a sliding cam sleeve _E_. The cam, in turn, operates fingers _F_, only one of which is shown, the latter acting upon the draw-in rod _C_ to which the collet is attached. By depressing lever _D_, the chuck is opened by means of the coil springs _G_ which act upon the draw-in rod _C_ when the pressure of the fingers has been released. Lifting up handle _D_ closes the chuck, and depressing it opens the chuck.

=Second Series of Machining Operations on Shrapnel Shells.=--The operations on the shrapnel shell performed in the second setting are shown in Fig. 18. The relieving tool _A_, held on the first face of the turret, covers that section of the shell which in the former operation was held in the gripping jaws. While this cut is being taken, a turret tool _B_ rough-bores the powder pocket and diaphragm seat. The relieving tool _A_ is constructed and operated similarly to the relieving tool described in connection with Fig. 16. It will be noted here that the threads on the spindle nose are protected by a cast-iron cap to prevent them from being injured. Upon the completion of the operation just described, the turret is indexed, bringing the second face in line with the spindle. Here the diaphragm seat is finished with a flat cutter _C_, which is held in the boring tool illustrated. The turret is again indexed into the third position, where the powder pocket is finished by means of the flat cutter _D_.

The turret is now indexed to bring the fourth face in line with the spindle where the extreme open end of the shell is turned taper by means of a tool _E_ that is carried on the front cross-slide and operated by the turret. By referring to this illustration, it will be noticed that the taper is turned from the spindle toward the outer end of the shell and is, therefore, a reverse turning operation. The tool is caused to move toward the turret by using a rack and pinion to reverse the movement. On this operation, as well as on the previous one, one man takes care of four machines.

=Third Machining Operation on Shrapnel Shells.=--Before any other machining operations are done on the shell, it is taken to a lead bath where it is heated and afterward placed under a press which closes in the nose or open end of the shell. For machining in the third operation, the shell is held practically in the same manner as for the second operation, except that it is gripped farther along the body. The machining performed in this operation is as follows: On the first turret face, rough-bore and finish-bore for a distance of 1 inch from the end of the shell; second turret face, rough-bore the inside of the shell for a distance of 1 inch back from the thread; third turret face, finish-form on the inside for a distance of 1 inch back of the thread; and fourth turret face, thread with a collapsible tap. The various machining operations on the 3-inch size of shrapnel shells are performed on a standard Potter & Johnston 6A automatic chucking and turning lathe. It is recommended that these machines be run in batteries or units of seven each, four machines being set up for the first operation, two machines for the second operation, and one machine for the third operation.

=Machining “Frankford” Forged Shell.=--The machining of the American or “Frankford” 3-inch type of high-explosive shrapnel shell is comparatively easy, inasmuch as there is no nosing to be done, and the entire shell may be machined at two settings. Fig. 20 shows the way in which the first operation is taken care of on the No. 6A Potter & Johnston automatic chucking and turning lathe. The forged shell is held on an expanding arbor of the same type as that shown in Fig. 15. In the first turret position, the operations consist in taking a straight cut across the diameter and facing off the end. The external turning tool _A_ is of the relieving type, and _B_ is a facing tool that works on the end. Both of these tools are supported and operated from the turret. A roll support, not shown, steadies the work while tool _A_ is working. The turret now backs out, and a forming tool, held on the cross-slide, advances, cuts the rifling band and the semicircular grooves in the end of the shell, and at the same time chamfers the corner. Knurl _D_, held on the rear of the cross-slide, is then advanced. This knurls the bottom of the rifling band groove.

By referring to Fig. 20, it will be seen that the grooves do not extend entirely across the face of the knurl, but instead two “knurl” ribs similar to a double thread are formed on the periphery. This construction makes it possible to sink the knurl into the work to the proper depth without exerting excessive pressure on the arbor and throwing it out of line.

=Second Series of Operations on “Frankford” Forged Shrapnel Shell.=--For the second series of operations, the “Frankford” shrapnel shell is held in a draw-in collet as shown in Fig. 21. As the shell has been completely machined on the outside, it is let into the collet for a considerable distance. For machining, it is shown gripped in the collet by jaws _A_ and is backed up by positive stop _B_. At the first turret face, tool _C_ rough-bores the diaphragm seat, tool _D_ bores the thread diameter, and tool _E_ faces and chamfers the end. The turret is now indexed, and tools _F_, _G_, and _H_ perform similar finishing cuts. A holder held on the third turret face carries tool _I_ that chamfers the powder pocket, and at the fourth turret face a collapsible tap threads the open end.

=Making Shrapnel Shells on the Gridley Automatic Turret Lathe.=--Figs. 22 to 25 show a three-inch shrapnel shell made on the 3¹⁄₄-inch Gridley single-spindle automatic turret lathe. The steel from which the shell is made is very tough. The specifications are from 125,000 to 135,000 pounds tensile strength, 110,000 pounds elastic limit, a twenty-five per cent reduction of area, and a twelve per cent elongation. It will be seen from the above specifications that the steel is, of necessity, very tough and difficult to work; in addition, a large taper reamer must be used, and the outside of the shell must be relieved throughout the central portion. It is also necessary to machine the piece to extremely accurate dimensions, all of which tends to make the work still more difficult. Fig. 22 shows a view of the shrapnel shell. It is approximately three inches in diameter and eight inches long, and the limits allowed for the sizes are extremely close throughout, both inside and outside. Figs. 24 and 25 show the successive steps employed in machining the piece complete, the four views presented representing the appearance of the work and the operations performed at each indexing of the turret. Fig. 23 will enable the operation of the different parts to be more clearly understood.

While the operation of the Gridley automatic turret lathe is generally understood by mechanics, it may be well to state briefly the general principles upon which work is done in the single-spindle machine. In this type of machine, the position of the work does not change as it does in the multiple-spindle machine, but the turning is accomplished by the operation of tools mounted on tool-slides which, in turn, work on a turret that revolves about a horizontal axis, successively presenting the tools for operation upon the work. This will be readily understood by glancing at the illustration Fig. 23. It will also be noticed from this illustration that the forming tools and cutting-off tools are operated from a face-cam at the lower part of the machine. The forming slide is actuated by a cam groove cut in one side of the cam-plate while the cutting-off slide receives its movement from a cam groove on the reverse side of this plate.

At the first position of the turret, a large 2¹¹⁄₃₂ inch high-speed oil drill is run into the bar to a depth of 6¹⁄₃₂ inches, and, at the same time, a knee-turner located on the tool-slide turns the outside of the stock, thereby removing the scale from the bar. Referring to Fig. 23, which shows the turret in the third position, the end of this large drill is shown at _A_, and, of course, when at work, it would be in the position of the reamer which is shown at _F_. The time elapsed at the completion of this part of the work is eleven minutes, five seconds.

At the second position of the turret, a smaller drill, 2¹⁄₁₆ inches in diameter, which is shown at _B_, is run in at the bottom of the hole previously drilled to a depth of ²⁹⁄₃₂ inch. At the same time a counterboring tool, which is located at _C_ and which is attached to the drill with a set-screw, is at work counterboring the end of the hole in the shell. During the time that this drilling and counterboring operation is being performed, the forming tool shown at _D_ is being fed into the outside of the head of the shell, finishing the three grooves as shown; in addition, a sizing tool _E_, which is at a fixed distance from the forming tool, comes in and sizes the work to exactly the right length. The time elapsed up to the finishing of this part of the work is thirteen minutes, thirty-five seconds.

At the third position of the turret, which, by the way, is the one shown in Fig. 23, the large taper reamer _F_ is run in, which operation removes the bulk of the stock for the taper, and a second step at the end of this reamer finishes the extreme end of the hole at the bottom of the shell. The blades of this reamer are nicked to break the chips as they are being formed. Before the reamer begins to cut, the knurling tool _H_ is brought against the work (while it is on the high speed) by the cutting-off slide, which, of course, results in a better knurled section than would result if the knurling of the piece were done at a lower speed. During the reaming operation, the cutting-off tool _G_ is run in part way to facilitate the final severing of the piece. In addition, the relieved part of the work is turned by a tool mounted in a tool-holder on the slide of the turret. This tool is shown at _I_ and it is operated by a templet _J_ which has a raised projection that throws the tool into the work after it has reached the right position with relation to the length of the shell. The total time elapsed up to the finishing of this part of the work is twenty-two minutes, thirty-five seconds. At the fourth and last position of the turret, a finishing reamer sizes the outer end of the interior of the shell and is withdrawn but part way, so that, when the cutting-off slide comes in and finishes severing the piece, the shell is caught on the reamer and not allowed to drop and possibly be injured by so doing.

The average total time for making this piece complete is twenty-seven minutes. On account of the rigidity of the tool support, the tools do not require sharpening more often than once for fifty pieces, with the possible exception of the cutting-off tool, which must be sharpened after about half that number of pieces have been completed.

=Using Warner & Swasey Turret Lathe for Machining Forged Shrapnel Shells.=--In Fig. 26 is shown a typical set-up on a Warner & Swasey No. 2A universal hollow-hexagon turret lathe for machining an 18-pound shrapnel shell forging. The arrangement of the various tools for performing the first series of operations is more clearly illustrated in Fig. 27, to which reference should now be made. The forging is located for machining on a special arbor fitted into the spindle and carrying two spring-controlled centering bushings _A_. These serve to locate the shell, which is then gripped by the floating jaws of the chuck on the external diameter, and a stop on the end of the arbor locates the shell from the bottom of the powder pocket.

The first operation consists in taking a cut from the external diameter with a special box-turner provided with a roll steadyrest and carrying two turning tools. The second operation is handled from the cross-slide, the shell forging meanwhile being supported by a roll steadyrest clamped to the turret. In this operation the closed end of the shell is faced with tool _C_, the corner rounded, and the band groove formed with forming tool _D_. The third operation--first chucking--is performed with tool _F_ which produces the waves in the band groove, and is operated in the following manner: Referring to the lower left-hand corner of the illustration, it will be seen that a roll _G_ is brought in contact with the face-cam _B_, thus giving the desired oscillating movement to the waving cutter. The fourth and final operation consists in under-cutting the band groove with a tool clamped to the turret. This tool gages from the end of the shell by a revolving stop _H_, and is provided with two slides, set at the desired angle to each other and the work, carrying under-cutting tools _I_ and _J_. These slides are operated by handle _K_.

The second chucking on this shell is handled as shown in Figs. 28 and 29 on the same type of machine. As shown in Fig. 29, the shell for this operation is gripped in an automatic chuck, and a stop _A_ for locating it is held in the spindle. The first operation consists in roughing out the powder pocket and diaphragm seat with a cutter _B_, and rough-turning that portion of the shell held in the chuck in the previous chucking with a tool _C_. This tool is held in the cross-slide toolpost, and is controlled in its movement by a special guide fastened to the regular taper-turning attachment. The second operation finishes the powder pocket and diaphragm seat with a cutter _D_.

After the second chucking, the shell is heated on the nose, closed in and is then brought back to the turret lathe, when the operations are performed as shown in Figs. 30 and 31. Here, again, the forging is held in the automatic chuck and is located by a plug _A_ in the spindle. The first series of operations consists in boring, facing and chamfering the nose with a counterbore _B_, and at the same time turning the external radius on the nose with a tool _C_. Tool _C_ is held in the cross-slide square turret and is controlled in its movement by a special guide fitting on the regular taper-turning attachment.

The second operation, shown to the left of the illustration, consists in machining the radius inside the nose with a tool _E_, controlled in its movement by the special guide _D_, as previously mentioned. The third and final operation consists in cutting the thread with a collapsible tap _F_.

=Using Warner & Swasey Turret Lathe for Machining Bar-stock Shrapnel Shells.=--The method of machining shrapnel shells from bar stock differs somewhat from that used for forgings, and is handled on a No. 2A universal hollow-hexagon turret lathe. In this particular case, the shell blank, previous to machining in the turret lathe, is rough-drilled in a high-powered drilling machine to the bottom of the powder pocket. Assuming that this has been accomplished, the operations for the first chucking are then carried on as illustrated in Fig. 32. Here the shell is held in an automatic chuck and is located by a stop _A_. The first operation consists in counterboring the mouth with the counterbore _B_, and rough-turning the external diameter with tool _C_; second, counterboring with the cutter _D_ and turning further along the shell with a tool _E_; third, finishing the bottom with a cutter _F_ and facing the end of the shell with a tool _G_.

In the second chucking, the operations shown in Fig. 33 are performed. Here the shell is reversed in the automatic chuck and is located, as before, by a stop _A_. The first operation consists in turning that portion of the body held in the chuck in the previous chucking with a roll-supporting turning tool _B_. Second, supporting the shell with a roller support _C_ held on the turret, facing the end with a tool _D_, and chamfering the band groove and the end with a cutter _E_ held on the cross-slide square turret. The third operation is to support the shell from the turret, knurling with a knurl _F_ from the cross-slide square turret. Fourth, taper-turn from the end to the band groove with a tool _G_, guided by the taper-turning attachment.

For the third chucking, the shell, as indicated in Fig. 34, is held in the same manner as for the first chucking. First, it is recessed with a tool _A_ and brought into action by operating the special holder which has a cross-sliding movement; second, it is bored and faced with a counterbore _B_ from the turret, and taper-turned with a tool _C_ operated by a special guide from the taper-turning attachment. In the third operation, the thread in the nose is rough-chased with a tool _D_, controlled in its movement by the chasing attachment of the machine; fourth, the thread is finished with a tap and tap-holder _E_.

=Machining Shrapnel Shell Forgings on the “Lo-swing” Lathe.=--By adding a simple carriage to its “Lo-swing” lathe, the Fitchburg Machine Works, Fitchburg, Mass., has adapted this machine for machining shrapnel shells of different types. The following data and illustrations refer particularly to tooling used for machining the Russian and French shells. On the Russian shell, after centering, the forging _A_ is held on a special arbor _B_ shown in Figs. 35 and 36. Placed over this arbor is an expanding collar _C_, the inside surface of which is chamfered to fit against surface _D_ on the stem of the arbor. The section of the arbor next to the spindle is threaded and a large nut and handwheel _E_ are turned to pull the sliding sleeve _C_ along the arbor and thus expand it to firmly grip the inside of the shell forging. Sleeve _C_ is connected to the nut _E_ by a threaded collar _F_. After the forging is securely located on the arbor, which it should be understood extends to the bottom of the powder pocket to gage it for length, the tail-center _G_ is run in to support it.

To those familiar with the “Lo-swing” lathe, it will be appreciated that its chief efficiency lies in its system of multiple turning tools. Thus, on this job, tools _H_, _I_, _J_, _K_, _L_, and _M_ are all mounted on one slide, and in the illustration are shown in the positions they occupy after taking their respective cuts. At the beginning of the cut, turning tools _K_, _L_, and _M_ are drawn back clear of the work to allow sufficient clearance for tools _H_ and _I_ to operate. With the tools drawn back and the carriage at the extreme right of the bed, tool _H_ is the first to come in contact with the work. This tool takes a roughing cut over the body of the forging, finishing at the radius on the nose.

Tool _H_ is controlled in its action by a former pin on the tool-slide, held in contact with the face of cam former _O_ by a stiff spring. Former slide _O_ takes the place of the regular taper-turning former ordinarily used on the “Lo-swing” lathe. When the former pin in the slide carrying tool _H_ reaches point _P_ on former _O_, the tool is withdrawn to conform with the shape shown at _N_ on the forging. The tool is then fed in further toward the axis of the arbor, until the former pin reaches point _Q_ on the slide, when the radius on the nose is completed. Tool _H_ is the only one mounted on a taper-turning block.

Just after tool _H_ passes point _N_, tool _I_ commences to cut at the end of the forging, taking a finishing cut and ending up in the position in which it is shown in the illustration. After tool _I_ reaches this position, the other tools _J_, _K_, _L_, and _M_ are brought into action. Tools _K_, _L_, and _M_ are so situated on the carriage that no lateral feeding is required. When these tools are in action, the roller support _R_ takes the thrust. Tool _K_ roughs out the band groove and is fed into the work by a handwheel. Tool _L_ cuts the groove for attaching the brass case to the shell, and tool _M_, carried on the same block, faces the end. Tools _K_, _L_, _M_, and _S_ are located on the same carriage and are fed in together. Tool _S_ rounds the corner of the shell. The carriage on which tools _K_, _L_, _M_, and _S_ are located is now drawn back out of the way, and the entire carriage moved over so that tool _J_ can be used to under-cut the rifling band groove. After cutting off the center projection, the first series of operations on the shell is completed.

=Second Series of Operations on the Russian Shell.=--The second series of operations is performed on the inside of the shell on the “Lo-swing” lathe, which is provided with a special turret for this purpose. As is shown in Figs. 37 and 38, the shell _A_ is held in special collet jaws _B_ that have a two-point bearing on the shell. Stop _C_ in the spindle locates the shell in the chuck. To manipulate the chuck for tightening it on the work, handwheel _D_ is turned, carrying with it the nut _E_ and ring _F_. Ring _F_ carries pins sliding in slots in sleeve _H_ and driven into collet _B_, so that when nut _E_ is drawn back it also carries collet _B_ into the taper in sleeve _H_, closing the collet on the work. Turning handwheel _D_ in the opposite direction releases the grip of the collet _B_ on the work. The first operation is performed with tools _I_, _J_, _K_, and _L_. Tool _I_ bores the powder pocket, tool _J_ roughs the diaphragm seat, tool _K_ rough-turns the thread diameter at the shell mouth, and tool _L_ faces the end. The turret is now indexed, and boring-bar carrying tool _M_ is brought into operation. This tool turns the curved interior of the shell. To accomplish this, the turret locking-pin is removed, allowing the turret to float on its central axis. Fastened on the ways of the lathe at the rear of the turret by a clamp _O_ is the cam bracket _N_ carrying the guiding cam _P_. This cam, through pins _Q_ and _R_ in bracket _S_, controls the float of the turret and guides the cutting tool _M_. In the illustration, the tool is shown at the end of the cut. It will also be noted that one surface of the cam is curved and the other is straight; therefore, to compensate for this and also to steady the turret, pin _R_ is backed up by a spring. Clamp _O_ is now released and bracket _N_ moved back to allow the turret to be indexed. Bracket _N_ is located, when brought into the operating position, by a stop on the bed of the lathe.

In the third position, tool _R_ finishes the powder pocket, _S_ the diaphragm seat, and _T_ the thread diameter, whereas _U_ acts as an adjustable stop for the depth of the various tools. The fourth and last operation is tapping with a collapsible tap _V_. This completes the machining of the Russian shell on the “Lo-swing” lathe.

=Machining French Shrapnel Shell on “Lo-swing” Lathe.=--The machining of the French shrapnel shell is well suited to the “Lo-swing” lathe. A great many of the French shells are made from solid bar stock, and when this is the case, the first operation, performed as shown in Fig. 39, consists in rough-drilling. If the shell is made from a forging, this operation, of course, is dispensed with and the first tool used carries boring and facing cutters, as shown at _A_, _B_, _C_, and _D_. These rough-bore the three diameters on the inside of the shell and face off the end to length. The next operation is accomplished with two finishing boring tools _E_ and _F_, the depth of which is obtained by an adjustable collar _G_ that comes against the produced with a collapsible tap _H_. The turret is then indexed two holes, bringing the special recessing tool into position. This tool is of the cross-slide type and carries a back recessing cutter _I_. This completes the first series of operations on the shell.

=Second Series of Operations on Shell. French=--The second series of operations on a French shell is accomplished as shown in Fig. 40. Here the shell is held in the same manner as described in connection with Fig. 35. The forging is placed on arbor _B_ that has an expanding sleeve _C_ operated by the hand-clamping wheel nut _D_. Eight cutting tools are located on the carriage. Tool _A_ turns the diameter at the open end of the shell, _B_ the central part, _C_ cuts the band groove, _D_ chamfers the section adjacent to the band groove, _E_ chamfers the end of the shell, and _F_ knurls the band groove. Roll _G_, in connection with roll _H_, supports the shell while the knurling is being done, whereas tool _I_ faces off the end of the shell. At the beginning of the cuts, tools _C_, _D_, _E_, and knurl _F_, also roll _G_ and tool _I_, are withdrawn. This permits tool _A_ to cut the front end of the shell at the beginning and finish the diameter at the open end of the shell. Tool _B_ next comes into action and turns the central part of the shell. Tool _C_ is then located in the correct position for the band groove and the carriage on which tools _C_, _D_, and _E_ are located is fed straight in, cutting the band groove and chamfering. Knurl _F_ is then brought into position to knurl the groove, with roll _G_ backing up the work against roll _H_. The last operation is to cut off the center projection with tool _I_.

Fig. 41 shows the tool set-up on the “Lo-swing” lathe for machining the straight type of French shell, in which two tool-blocks are used for doing the straight turning. The leading tool turns the end of the shell a little larger than the main body. The procedure for grooving, knurling, and facing the shell is that previously described for the forged shell, which is shown in Fig. 35. On the French shrapnel shell the second operation follows directly after the first, whereas on the Russian forged shell a nosing-in operation comes between the two machining operations.