|
Continued:
Apart from an opening in the front to allow the use of a sliding tumbler selector the screwcutting and feeds gearbox was completely enclosed and lubricated by splash from an oil bath. Lubricant was designed to be flung into the roof of the box where it settled into cast-in troughs positioned directly above the various bearings from where it could be directed by drillings. To ensure that only clean oil drained down short pipes were fitted into each hole so allowing any dirt or swarf to settle undisturbed into the bottom of the trough. All shafts were made from case-hardened steel and ground and the special alloy steel gears heat treated. Changes of pitch and rates of power feed were made separately with the former altered by the juxtaposition of 4 levers in combination with the sliding selector and the latter by a rotary knob with 5 settings available without altering the gear train. The leadscrew was used only for screwcutting and the power feeds transmitted to the apron through a separate shaft protected by "ball-and-spring" overload clutch. The sliding rate ranging from approximately 0.002" through 0.004", 0.008", 1/64" to 1/32" per revolution of the spindle with the surfacing feed set at half those rates. Both feeds (but not screwcutting pitches) could be instantly changed without any need to stop the lathe. The gearbox was able to generate 34 metric threads from 0.2 to 7 mm pitch, 28 inch threads from 56 to 4 t.p.i., 13 Modulus threads from Mod 0.25 to 3.5 and 28 Diametric threads from 112 to 6 pitch.
The apron was a model of mechanical simplicity with the leadscrew clasped by twin nuts and the keyed power shaft passing through and driving a bevel gear that transmitted its motion to a set of spur gears. A single lever control on the face of the apron both selected and engaged the feeds and, because the mechanism did not become loaded under heavy cuts, it was possible to flick the drive in and out as required. A shallow oil trough ran along the top of the casting into which were inserted short tubes (possibly with wicks) though clean oil could be skimmed off to reach the various shafts.
Pivoting on the right-hand face of the apron was a conveniently positioned lever connected by a "third-rod" control to the spindle start, stop and reverse switch.
The saddle carried T slots in all four wings but, because bed ways stopped beneath the spindle nose the compound slide rest had to be positioned towards the saddle's headstock end in order to get the cutting tool right up to the faceplate. Both top and cross slides were adjusted with taper gib strips, carried ball thrust bearings on their feed screws and had clearly engraved zeroing micrometer dials with narrow knurled grip rings. The handles were traditional "balanced-ball" type that, whilst handsome, might have been considered rather hard on the operator's hands on a machine of this size.
With a No. 3 Morse taper the tailstock was correctly sized to the machine but the use of a direct-bearing screw to lock the spindle was unusual for the time when nearly every other lathe of this size had a compression fitting that squeezed top and bottom. The spindle also lacked either a graduated collar or ruler engravings to assist the operator gauge drilling and boring depths.
The lathe was 84 inches long, 33 inches wide and, equipped with its normal accessories, approximately 2645 lbs.
In 1952 the DIMCO 172 sold for £907 (about half the contemporary price of a UK house and twice average national earnings) and came with the following standard equipment: 2 spare gears to vary the screwcutting range, 14-inch independent 4-jaw chuck, electric motor and switchgear, fixed and travelling steadies, coolant pump and distribution piping, light unit, catch plate, headstock centre adaptor, centres for headstock and tailstock, adjustable carriage stop, a collection of 7 spanners including a "C" type to adjust the spindle front bearing..
|
|
