Finishing a Webbed Flywheel in Two Settings.—The plan views B and C, [Fig. 7], show the arrangement of tools for finishing a webbed flywheel which has to be machined all over. This, of course, requires two operations. In the first of these (see sketch B) the rough casting is chucked on the inside of the rim with regular inside hard chuck jaws b. The cored hole is first rough bored with cutter n attached to the end of boring-bar m, and guided by the drill support d pivoted to the carriage. Next, the boring-bar m1 is brought into position, the drill support being swung back out of the way. This bar is steadied by its bearing in bushing r in the chuck. Two cutters, n1 and n2, are used to roughly shape the hole to the desired taper, the small end being finished to within 0.002 inch of the required diameter. While boring with the bar m1, the scale is broken on the web and hub of the casting by the tool k in the turret toolpost. The latter is then shifted to bring the tool j into position for removing the scale on the periphery of the wheel. Next, the hole is reamed with taper reamer q, the pilot of which is supported by bushing r.
The first of the facing heads is now brought into action. This facing head carries a guide t which is steadied in a taper bushing c, driven into the taper hole of the hub for that purpose. The top cutter f turns the periphery, cutter g turns the hub and faces the web, and cutter h faces the rim. A fourth cutter e on the under side of the head faces the hub. This casting is now machined approximately to size.
For finishing, similar cutters, e1, f1, g1 and h1, in the other facing head are used, the latter being supported by the taper bushing c in the same way. A very light cut is taken for finishing. Tool l in the carriage turret is used to round the outer and inner corners of the rim, which completes the work on this face of the casting.
In the second cycle of operations, shown at C, the casting is chucked on the outside with the soft jaws b, which are bored to the exact diameter of the finished rim. The work is further supported and centered by sliding bushing c, which is tapered to fit the finished hole in the hub, and has an accurate bearing in bushing r in the chuck. This bushing is provided with a threaded collar for forcing it into the work and withdrawing it. The scale on the web and the inside and face of the rim is first broken with the tool k in the turret toolpost. These surfaces are then roughed off with cutters f, g and h, in the facing head. This latter is steadied by a pilot t which enters the hole in the sliding bushing c on which the work is supported. A light cut is next taken with cutters f1, g1 and h1, in the finishing facing head, which completes the operation.
Tools for Turret Lathes.—The operation of a turret lathe after the tools have been properly arranged is not particularly difficult, but designing and making the tools, determining what order of operations will give the most efficient and accurate results, and setting the tools on the machine, requires both skill and experience. For some classes of work, especially if of a rather complicated nature, many of the tools must be specially designed, although there are certain standard types used on turret lathes which are adapted to general turning operations. Some of the principal types are referred to in the following.
Fig. 8. Different Types of Box-tools for Turret Lathe