Machine-shop-work-ICS-The-Shaper-The-Slotter-B.html

pg 54 -55 Below

pg 54-SHAPER AND -SLOTTER WORK. •
Section § 11
SHAPER TOOLS. 10. Relationship Between Shaper and Plasm'. Tools.—As the cutting action of the planer andshaper the same, the same class of tools can be used on., both. I n the shaper, as in the planer, the shank of the tool is alw a in a plane perpendicular to the line of motion of the tool ()I the work, and hence the angle of clearance always remain constant. Special tool holders and inserted blade tools may be used in the shaper as well as in the planer. Tool holders, or i 1 fact any tools, cannot be used effectively both on lathe and planer or shaper work, on account of the fact that the ang of front rake, or clearance, is constant in the shaper and planer and varies in the lathe.
HOLDING THE WORK. 11. The Vise.—Most of the work done on the shape! is held in the chuck or vise. The methods employed setting the work square and true, so that it may be planed square and parallel, are the same as those used in setting work in the planer vise. There are some vises especially made for shape work. As a rule, the planer vise is provided with no method ()I adjusting the vise on the base after the work is clamped in position, but shaper vises are usually provided with a screw by means of which the vise proper and the work can be adjusted. Such a vise is shown in Fig. 5. The base of t.in vise a is clamped to the shaper table. By means of the graduated circle shown at b, the body of the vise c can be set at any desired angle with the slide e. When set to the desired angle, the vise is clamped to the slide by means of the nuts shown in the pockets at the sides. The slide e can 4 be fed back and forth across the base a by a screw operated by the handle d. The body of the vise c is provided with a fixed jaw g- and a movable jaw h. The rnovable jaw is adjusted by means of the screw 1, which is operated by the

9 SHAPER AND SLOTTER WORK.
pg-55
tench f. After the jaw h is in the desired position, it is cured by a clamp nut k. The jaws g and It have removable steel faces. For work on cylindrical pieces, one of the
FIG. 5.
movable jaw faces is sometimes replaced by a V-shaped ock that will facilitate the holding of any cylindrical ece of work. 1 2. Clamping Work.—When work is of such a form at it cannot be held in a vise, the vise is removed and the work fastened to the table. This is done with bolts, straps, d clamps in a manner similar to that in which work is stened on the platen of the planer table. Sometimes toe amps and plugs are also employed. With traveling-head apers, very large castings or forgings that have small surfaces to be machined are frequently blocked up in front of e machine on suitable jacks and blocking, and clamped her to the table or front of the machine and then operated on by the tools.
TAKING THE CUT. 13. Range of Utility of the Shaper.-For short is on pieces of relatively small size, the shaper is usually tter adapted than the planer. For cutting slots or key-Lys, or for cuts that terminate close to a shoulder, the 50-9

page 56-57 Machine-Shop-Work- The Shaper. 9

shaper possesses the advantage that it can be more readily set to take a particular length of stroke, and it will then cut that exact length of stroke each time. This js true partic-ularly of the crank-shapers, but only to a limited extent is it true of geared shapers. On the planer or geared shaper the reversing point is not positive, because of the uncer, tainty in the slip of the belts and the gripping of the pulleys by the friction clutches.
1 4. Cutting a Keyway.—Whenever a cut terminates in the metal, a notch must be cut at the end so that the tool will pass out of the cut each time. Suppose that a key-way is to be cut in the end of a shaft, as shown in Fig. 6 (a) .

(a)
(b) FIG. 6.
(c)
The keyway should first be laid out by scribing lines to indicate its width and depth. At the place where the key-way terminates in the shaft, a circle is described equal in diameter to the width of the keyway. In this circle a hole is drilled, as shown in Fig. 6 (b), equal in depth to that of the keyway. The work is then set in the vise or clamped to the table, so that the lines on the end that indicate the sides of the finished keyway are perpendicular to the shaper table.. In the case of a fairly large keyway, or when no tool of the right width is at hand, slots are cut along the outside edges of the keyway, as shown in Fig. 6 (c). This work is done with a parting tool. After the slots have been cut, the

§ 9 SHAPER AND SLOTTER WORK. pg-57

metal shown at a, Fig. 6 (c), is removed with a square-pointed tool. If an attempt is made to take such a cut as is shown in Fig. 6 without first drilling or otherwise cutting out a place for the tool to run into, and thus cut off the shaving, each shaving will clog the slot slightly, so that after a few strokes the tool will strike with great force against solid metal. If the cut is continued, the tool will break, or the work will be pushed from the machine. Large keyways are usually cut with several settings of the tool, as shown in Fig. 6. Small keyways are often cut by using a tool just the width of the slot. When the key-way is finished at one cut, it is well to drill two holes at the end and chip out between them so that the tool can be lifted clear of the work for the back stroke. With a single hole there is danger of the work catching the tool. When the keyway is cut the entire length of the work, there is no difficulty in lifting the tool for the back stroke. In some cases the keyway is planed a little narrower than desired, with the square-nosed tool, and the sides are finished with a side tool.
1 5. Cutting to a Shoulder.—Suppose that it is necessary to take a cut over the piece of work shown in Fig. 7, and that the surface e is to be partly removed up to

FIG. 7.

the line A B, as indicated by the dotted lines. Before this cut can be taken on the shaper, it will be necessary to cut a groove at A B equal in depth to the amount to be removed. This groove can be cut with a cold chisel and a hammer or by first drilling a hole at a and then cutting the groove on

TOOL-MAKING P

Page 58 SHAPER AND SLOTTER WORK-Sectionn§9
the ' shaper with a parting tool. The part of the surface e indicated by dotted lines can then be easily planed away. In castings, when it is known that such cuts as these are to be taken, much work can be saved by coring out a space where the cut is to terminate. This saves the time required for
cutting a groove with the chisel or by planing.
1 6. Clamping Work to the Saddle.—Work that is too high to be placed on the shaper table, or work that can-not be clamped to the table on account of its shape, can frequently be clamped to the saddle. An example of this is shown in Fig. 8, which shows a pair of legs for a lathe

FIG. 8.
clamped in position for shaping the upper surface. The table and vise are removed and the work a secured to the saddle by bolts and blocking. This method of holding work is similar to attaching it to an angle plate fastened to a planer platen.

Page-59 S§ 9 SHAPER AND SLOTTER WORK.

When work is clamped against the front of the saddle, it is not always possible to test the setting with a surface gauge. This is also occasionally the case when rather large work is clamped to the top of the table. Then the setting of the work may be tested by means of a level or by a pointed wire, a scriber, or a tool held in the tool post, while moving the ram by hand. In some instances, the ram can be run out until it extends clear over the work a surface gauge can then be inverted and held up against the bottom of the ram, along which it is moved in order to test the setting of the work. 1 7. Rack Cutting.—In some cases the shaper may be used as a rack cutter. The vise is set with the jaws at right angles to the line of motion of the tool, and the rack blank is clamped in it. A tool having its cutting edge formed to give the correct shape of tooth is set in the tool post, and is fed down into the work, thus cutting out the space between two teeth of the rack. The work is then moved sidewise the correct distance to cut the second space, and the tool is again fed into the work to the same depth as before. For comparatively rough work, the spacing of the teeth may be laid out on the face of the rack, and Ole tool set as near as can be judged to the marks by mov\itig the saddle by means of the feed-screw. A better way is to use the feed-screw as a spacing device. When the feed-screw is used for spacing the teeth, it is treated as a micrometer screw. The pitch of the screw is measured and a calcula-tion made to. see how many turns and what part of a turn will be necessary to advance the work one tooth. To make the fraction of a turn, it is necessary to provide some kind of an index on the feed-screw. Frequently one of the change gears belonging to a lathe can be clamped on the screw and used as an index plate. EXAMPLE. —Let it be required to cut a rack to mesh with a 4 diame-ti'al pitch gear. (The circular pitch, or distance from the center of one tooth to the center of the next on the pitch line, for 4 diametral pitch is equal to .785 inch.) The work is to be done in a shaper having 4 threads per inch on the feed-screw for the saddle.

pg 168-169

pg-168 MACHINE SHOP WORK, Milling Gears
Gears. The cutting of gears of all descriptions was formerly done on some type of milling machine, although now each type of gear may have its special and, in many cases, automatic machine.

Fig. 243. Gear Cutter with Divided Head
Forms of Cutters. The cutters for milling spur and bevel gears are of two types, producing both the cycloidal and the involute tooth. For each pitch, the cycloidal system requires twenty-four cutters, while eight cutters usually suffice for the involute system. These cutters are plainly marked with the style of tooth, pitch, and number of teeth for which they are suitable. Some cutters are also marked with the full depth of the tooth expressed in thousandths of an inch, Fig. 279. The gear blanks, having been very carefully turned as to outside diameter, are mounted on an arbor be-tween centers, and the cutter placed so that its central plane passes through, and is parallel to, the axis of the arbor. Clamp the saddle in this position; raise the table knee until the cutter, when rotating, just touches the outside of the blank. Using the table screw, move from under the cutter; using the graduated dial, raise the knee an amount equal to the whole depth of the gear tooth. With the exception of the indexing, the gear blank is now ready to be cut, Fig. 242.

Fig. 244. Cutting a Bevel Gear
MACHINE SHOP WORK
169
Use of Dividing Head. In order that the gear may be accurately and quickly set for cutting each tooth, a dividing head is used, which is shown in Fig. 243. The mandrel upon which the gear blank is mounted is held by the centers AA, and firmly dogged to the face-plate B. The index plate C is geared to the head spindle that carries

Fig. 245. Hobbing Teeth in Worm Wheel Courtesy of Brown and Sharpe Manufacturing Company, Providence, Rhode Island the faceplate B; the index plate is provided with a number of holes. These holes are arranged in circles, each circle having a different number of holes, and these holes are accurately spaced at equal distances apart. The arm D carries a stem E, having a knurled head - at one end andaaPinn at the other. The pin is held in one of the holes. holes

pg-152 TOOL-MAKING
Another method of getting the clearance for the cutter is to place, the top of the cutter blank as near the arbor as possible, and then to', cut the desired shape. If the cutter is set in the arbor so that it

Fig. 232, First Step Fig. 233. Fly Cutter in Making Fly Set Radial with Cutter Clearance Provided

Fig. 231. Simple Method of Getting Clearance on Fly Cutter
projects from the surface, it will have the necessary clearance, as shown in Fig. 234. A represents the position of the blank while being cut, and B the cutter in position for cutting; as the dotted line shows the circle through which the cutting edge travels, the amount of clearance is apparent. End Mills. This form of milling machine cutter, Fig. 235, is familiarly known as a shank mill, on account of the shank, which in small milling cutters fits into a collet. This collet in turn fits the hole in the spindle of the milling machine; the collet is used to save stock in making the cutters, as otherwise it would be necessary to use steel large enough to make a shank the size of the hole in the spindle of the milling machine. The cutter shown in the figure is what is termed a left-hand mill; if the teeth run in the opposite direction, it is called a right-hand mill. In making a shank, or end mill, of the form shown, stock should be selected enough larger than the cutting end to allow of turning

Fig. 235. Straight Flute Left-Hand End Mill Courtesy of Becker Milling Machine Company, Hyde Park, Massachusetts off the decarbonized surface of the steel. After the ends have been faced to length, and the roughing chip turned, the cutting end can be run in the steady rest of the lathe, and the center cut away, or

pg-153 TOOL-MAKING
recessed, as shown at the end of the mill. The blank should be re-centered and countersunk, to furnish a center to use in turning the mill to size and shape. The object in cutting the center out as shown is to furnish a cavity for the angular cutter used in cutting the teeth on the end of the mill. Without the recess, it would be impossible to grind satisfactorily. After re-centering the recessed end, the opposite end should be turned to size and milled to thickness, which should be a trifle-11,2 inch—less than the width of the center key slot in the collet. The taper shank should be turned enough larger than finish size to allow for grinding after the milling cutter is hardened ; the cutter end should be turned .010 inch larger than the required diameter ; the portion just back of the cutters should be turned 1-2- inch smaller than

Fig. 236. Cutter with Weak Teeth

Fig. 237. Cutter with Well-Formed Teeth

Fig. 238. Cutter with Especially Strong Teeth

Fig. 239. Method of Cutting Strong Teeth
the large end of the shank, or to dimensions, if any are given on the drawings. In order to insure teeth strong enough to resist the strain of cutting, an angular mill should be selected that will give the required shape. In Fig. 236 is shown a form of cutter tooth too weak for actual service, the result of using an angular cutter with a cutting face forming an angle that is too acute with the side. Fig. 237 illus-trates a cutter whose teeth are strong, yet deep enough to be practical; these teeth were cut with an angular mill of smaller angle. Fig. 238 represents a cutter whose teeth were cut with the same cutter used for Fig. 236. The teeth were cut to the required depth first, but this of course left them too thick at the cutting edges A, Fig. 239, and the index head was turned sufficiently to cut the teeth as shown at A, Fig. 238. After the teeth around the circumference of the mill have been cut, the mill should be placed in the collet, and the collet put in the spindle hole in the spiral head to cut the teeth on the end. When
Fig. 231.the last last Fly-Cutter Arbor

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MILLING-MACHINE WORK. § 13
carry the cutting tools. Each spindle, and hence each cut-ting tool, is usually made to be independently adjustable in relation to the work. In most machines of this class, the work can be moved in a straight line in one direction only. Multispindle milling machines are intended for finishing several surfaces simultaneously, and are usually en-iployed for heavy work only. 1 6. Special milling machines may take any con-ceivable form that will adapt them for the class of work for which they are designed, but no matter in what manner they are constructed, the principles of operation will be the same as those of any regular milling machines.
CONSTRUCTION OF MACHINE.
ESSENTIAL PARTS.
17. A milling machine consists of certain essential parts, which in some form or other must exist in any of its numerous modifications. The essential parts are the frame, the spindle, the table, the feed-mechanism, and the cutting tool. The function of the frame is the supporting of the spindle, table, and feed-mechanism. The spindle, which by suitable means is revolved in bearings provided for it in the frame, carries the cutting tool. The function of the table is to serve as a support for the work, which may be attached either directly to the table or to holding devices carried by it. The feed-mechanism serves to move the work past the cutting tool ; it may operate directly upon the table, or upon the spindle, or upon both. The function of the cut-ting tool is self-explanatory.
CONSTRUCTION.
1 8. The universal milling machine is the most advanced form for general work, and embodies all the features found in other types. For this reason it is here selected and
§ 13
MILLING-MACHINE WORK.
described. As far as the universal machines of various makes are concerned, their general arrangement is similar

to that of the machine illustrated in Fig. 1; they differ only in the design of the details, which are modified in accordance
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