Part 13 (1/2)
[Illustration: Fig 10 Exans]
Sketch _C_ shows the box-tool used for the second operation As the hub is flush with the rim on the side for which this tool is intended, it needs only one cutter to face both This is done by the wide cutter _a_ which is held in a dove-tailed slot in the front of the tool and is fastened by the cla _d_, in which the end of the work arbor is supported, is held by the collar-screw _e_, and to obtain the necessary compression, the body of the tool is slotted as far back as _f_ This bushi+ng is provided with oil grooves and one side is cut away to clear the cutter _a_ The pilot end of the arbor on which the work is mounted is 1/16 inch smaller than the bore of the pulley, which allows the cutter to be set in far enough to prevent any burr which e of the bore A disk _i_ is inserted back of bushi+ng _d_, so that the latter h the hollow shank The special chuck used for this second operation on the loose pulley is screwed onto the spindle, and the work isholes in the pulley web The arbor isfit for the work, and the end or pilot is a running fit in the bushi+ng of the box-tool A counterbore in the arbor hub provides clearance for the hub of the pulley which projects beyond the ri 11 (A) Hollow Mill and Holder (B) Spring Screw-threading Die and Releasing Die-holder]
=Hollow Mills=--A hollow11 is so brass) for short roughing cuts preceding a threading operation The turning is done by the cutting edges _e_, and the turned part enters the mill and is steadied by it If this type of tool is used for long, straight cuts, especially on square stock and when e heads fro box-tool to insure accurate work A hollowthe ends without ht adjustment can be obtained by h this is not generally used Whenfro steel, the cutting edge should be about 1/10 of the diameter ahead of the center, whereas for brass, it should be on the center-line
[Illustration: Fig 12 Geo Tool]
Hollow12 is especially adapted for brass finishi+ng It can also be used for taking light cuts on cast iron or steel but its use in place of roughing or finishi+ng box-tools for general use is not recommended With the exception of the cutters and screws, the complete tool consists of three parts, _viz_, the holder, ca The cam serves to adjust the cutters for different diameters The adjust indicated by a iven dia of the required size is advisable, the cutters being adjusted against the plug
=Releasing Die and Tap Holders=--Threads are cut in the turret lathe by , and taps for internal threading, the die or tap being held in a holder attached to the turret A si 11 This holder was designed for the spring-screw type of threading die shown to the left
The die is clamped in the holder _a_ by the set-scren, and the shank _b_ of the holder is inserted in the turret hole Holder _a_ has an extension _c_ which passes through the hollow shank When the die is pressed against the end of the work, holder _a_ and its extension_e_ on the shank The die and holder are then prevented froins to cut a thread It continues to screw itself onto the ith the turret following, until the thread has been cut to the required length; the turret is then stopped and as the die and holder _a_ are drawn forward, lugs _d_ and _e_ disengage so that the die si to advance The lathe spindle is then reversed and as the turret is _, thus holding the die stationary; the die then backs off from the threaded end Some tap holders are also constructed the sa ns in use, some of which operate on this sa 13 Geo Die Head]
=Self-opening Die Heads=--The type of die holder shown at _B_ in Fig
11 is objectionable because of the ti the die off the threaded end; hence, self-opening dies are extensively used in turret lathe work As the na solid, has several chasers which are opened autoth The turret can then be returned without reversing the lathe spindle The dies are opened by si the travel of the turret slide, the stop-rod for the feed of the turret being adjusted to give the proper a 14 Geo Tap]
A well-known die head of the self-opening type is shown in Fig 13 The dies open automatically as soon as the travel of the head is retarded, or they can be opened at any point by si back on the turnstile or lever by which the turret slide is ain by les froa pin into a threaded hole opposite the handle and attaching a se of the turret slide The latter will then engage the pin as the turret revolves, thus closing the die head This die head has a roughing and finishi+ng attachment which is operated by handle _A_ When this handle is moved forward, the dies are adjusted outward 001 inch for the roughing cut, whereas returning the handle closes and locks the dies for the finishi+ng cut The die head has a ht adjustments to coht-or a loose-fitting thread
=Collapsing Taps=--The collapsing tap shown in Fig 14 is one of ns that are manufactured They are often used in turret lathe practice in place of solid taps When using this particular style of collapsing tap, the adjustable gage _A_ is set for the length of thread required When the tap has been fed to this depth, the gage comes into contact with the end of the work, which causes the chasers to collapse automatically The tool is then withdrawn, after which the chasers are again expanded and locked in position by the handle seen at the side of the holder In all threading operations, whether using taps or dies, a suitable lubricant should be used, as a better thread is obtained and there is less wear on the tools Lard oil is a good lubricant, although cheaper coive satisfactory results on many classes of work
=Miscellaneous Turret Lathe Tools=--The cha the end of a bar before running on a roughing box-tool This not only finishes the end of the bar but provides an even surface for the box-tool to start on The cutter is beveled on the end to forle
The back-rest consists of a bell- which supports the bar while the cut is being taken
The stop gages _B_ and _C_ are used in the turret to govern the length of stock that is fed through the spindle When a finished piece has been cut off, the rough bar is fed through the spindle and up against the stop gage, thus locating it for another operation This gage may be a plain cylindrical piece of hardened steel, as at _B_, or itscrew as at _C_; for special work, different fores on so held in the turret, are attached to a swinging ar up in line with the spindle when the stock is fed forward
The center drilling tool _D_ is designed to hold a standard combination center drill and rea parts that , to for tool _E_ is used for turning the outside of gear blanks, pulley hubs or the rims of small pulleys The pilot _a_ enters the finished bore to steady the tool, and cutter _b_ is adjusted to turn to the required dia 15 Various Types of Tools for the Turret Lathe]
The cutting-off tool-holder _F_ (which is held on the cross-slide of the turret lathe) is usually ular toolpost, as the blade can be set closer to the chuck The blade is held in an inclined position, as shown, to provide rake for the cutting edge; the inclined blade can also be adjusted vertically, a li-off tool _G_ holds two oroff several washers, collars, etc, si the distance pieces between the cutters, the latter are spaced for work of different widths The flat drill holder _H_ is used for drilling short holes, and also to for point for other drills
Knurling tools are shown at _I_ and _J_ The forths and is sometimes clamped on top of the cut-off tool on the cross-slide, the end being swung back after knurling (as shown by the dotted lines) to prevent interference with the hen the cutting-off tool is in operation The knurling tool _J_ has a shank and is held in the turret The two knurls are on opposite sides of the work so that the pressure of knurling is equalized By adjusting the arms which hold the knurls, the tool can be set for different diameters
Three styles of drill holders are shown at _K_, _L_ and _M_ Holder _K_ is provided with a split collet (seen to the left) which is tightened on the drill shank by a set-screw in the holder This holder requires a separate collet for each size drill The taper shank drill holder _L_ has a standard taper hole into which the shank of the drill is inserted
The adjustable type of holder _M_ is extensively used, especially on small and medium sized machines when several sizes of drills are necessary This holder is sie drills the plain style of holder _K_ is recommended, and if only a few sizes of drills are required, it is more satisfactory and economical than the adjustable type
The various types of s for turning, threading, tapping, knurling, etc, are a few of the ns of tools used in turret lathe practice
Naturally, the tool equiped so each case The tools referred to, however, represent in a general way, the principal types used in ordinary practice Some of the more special tools are shown in connection with examples of turret lathe work, which are referred to in the following
=Turning Gasoline Engine Pistons in Turret Lathe=--The ines, especially in autoe scale that rapidthe 16, shows the turret lathe tools used in one shop for doing this work As is often advisable ork done in large quantities, the rough castings are ed as to assist in holding them These projections are, of course, removed when the piece is co about 1-1/4 inch long and a little less in dia end The piston is held in suitable chuck jaws _b_ which are tightened against the inside of this ring The set-screws in these special jaws are then tightened, thus cla between the points of the screws and the jaws Thispermits the whole exterior of the piston to be turned, since it projects beyond the chuck jaws This is the object in providing the piston with the projecting ring by which it is held
[Illustration: Fig 16 (A) Method of Boring and Turning Pistons in Gisholt Lathe (B) Special Chuck and Tools for Turning, Boring and Cutting Off Eccentric Piston Rings]
The first operation consists in rough-boring the front end of the piston The double-ended cutter _n_ is held in boring-bar _m_, which is, in turn, supported by a drill-holder, clamped to one of the faces of the turret This bar is steadied by a bushi+ng in the drill support _c_ which is attached to the carriage, andposition, as required After this cut is completed, the turret is revolved half way around and the casting is finish-bored in a similar manner, with double-ended cutter _n_{1}_ held in bar _ used as in the previous case The support is then turned back out of the way to allow the turning tools in the turret toolpost to be used