This article was originally published in Practical Engineering 1940 Vol No1. Information within this article is therefore correct as of 1940. The publication of this material aims to provide historical insight on the subject and its place in industry.
A compact and powerful modern tool that is equally suitable for either chuck work or production from bar is the Ward No.2a capstan lathe illustrated on this page. The makers are the well-known Birmingham firm of H. W. Ward & Co., Ltd., of Dale Road, Selly Oak, Birmingham, 29.
As in the case of. many other Ward lathes, this particular model can be equipped with a pneumatic or hand-operated chuck, whichever may be suitable for the work to be performed. The headstock is of a new type, allowing fast speed-changing through friction clutches which run in oil. Six spindle speeds in each direction are available, and these are arranged in three groups so that two forward and two reverse speeds are attainable without the necessity of moving the gears.
The required range of gears is obtained by the partial rotation of a lever on the front of the headstock, which operates sliding gears. There are no loose gears to be manipulated and no internal belts, while the "group speed" selection is practically instantaneous. An automatic brake motion is incorporated with both clutch operating levers. The spindle is brought to rest by the simple action of moving either clutch lever to its central position. The action of reversing the spindle also applies the brake automatically, and thus relieves the reverse clutches of all strain.
The spindle is mounted on combined ball journal and thrust bearings, together with a heavy duty roller bearing, and all rotating parts of the headstock are also carried on suitable ball and roller journals. Automatic pump lubrication is supplied to all bearings and gears. The spindle has a 1-3/8-in. Clear hole throughout its length, and by the use of the automatic chuck, bars up to 1-1/4in. diameter can be handled.
With the headstock pulley driven at 450 r.p.m. a speed range from 48 to 1,020 r.p.m. is available, but driving the main pulley at 675 r.p.m. gives spindle speeds between 71 and 1,531 r.p.m. while the speeds available with the main pulley running at 900 r.p.m. are 95 to 2,041 r.p.m.
By fitting a two-speed A.C. electric motor and switchgear, the speeds can be increased to 12 in number, and if a four-speed electric motor is employed, 24 speeds, ranging from 30 to 2,041 r.p.m. are available.
The location of the single pulley makes the machine equally suitable for driving from the line shaft or by direct electric motor through suitable vee ropes.
Movement of the sliding saddle and cross slide is provided for by means of handwheels. The longitudinal motion is through rack and pinion and five stops are provided. The cross slide is actuated through a square-thread screw and nut, and is fitted with a large-diameter indicating dial. Two tool posts are fitted as standard, but a square turret can be provided if desired.
The design of the capstan rest is such that it can be clamped to the bed in any desired position. The slide has wide and accurately fitted bearings, and is provided with taper strips which are adjustable to take up wear. The slide is actuated by a star wheel, through a pinion and rack. The turret is hexagonal in form and is provided with tool holes bored from the headstock, thus ensuring accuracy. In addition, each face of the turret is surfaced, drilled and recessed for the attachment of toolholders with flanged bases.
The normal stroke of the top slide when using the automatic revolve motion is 6in. by rack and star handle, but if the turret is rotated by hand a useful stroke of 8 Jin. is obtainable. This is particularly useful when using pilot boring bars, or when turning long bolts, etc.
The revolving and indexing motions are automatically performed on the return or backward stroke of the capstan slide, and an arrangement is provided whereby the revolving and indexing motions can be rendered inoperative at any time. This is most useful when simple work, calling for the use of one tool only, is in hand.
A feature which will be found most useful when drilling or turning for any length is the automatic feed to the capstan slide. This is provided by means of a gearbox attached to the capstan rest, and driven from a feed shaft along the front of the machine. Two rates of feed are provided, and the feeds can be automatically tripped by means of standard stops, or are instantaneously actuated by hand.
When the lathe is intended for bar work, it is usually fitted with the standard automatic chuck, which is designed for rapid and accurate chucking of bars and tubes or short pieces for second process work. The chuck is self contained and dispenses with the tube through the spindle usually found in spring collet type chucks, so allowing the machine to deal with material up to the full diameter of the hole through the spindle. The chuck is operated by a single lever situated in a most convenient position for the operator. The whole chuck can be easily dismantled to facilitate cleaning, and as the whole of the mechanism is locked together when work is being gripped, high speeds can be maintained without fear of trouble.This lathe can also be fitted with compressed air operated bar or jaw chucks. The bar chuck is a recent introduction of patented design, and an important feature is that the grip, once applied, is not dependent upon the maintenance of air pressure.