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Colchester Mascot 8.5-inch (215mm) centre height lathe
Continued: Totally enclosed, the dual Metric/English screwcutting gearbox was lubricated from an oil bath and fitted with hardened and ground gears running on ball-race supported shafts. Three conventional levers together with a 6-position joystick that moved into radial slots around a circle, swapped the ratios. The box was able to generate a wide range of pitches without dismounting or changing any of the changewheels; the range of threads comprised: 40 Metric from 0.4 mm to 14.0 mm; 18 Module from 0.3 to 3.5m; 38 English from 2 to 72 t.p.i. and 27 Diametral from 8 to 60 D.P. The range of sliding feeds varied from 0.002" to 0.032" (0.06 mm to 1.0 mm) and surfacing feeds at half those rates (and thus) from 0.001" to 0.016" (0.03 mm to 0.5 mm) - all per revolution of the spindle. Doubled walled, with its shafts supported on ball bearing at each end, the apron held gears that were all hardened and ground; the base was closed off to form an oil bath to splash lubricate the internals and at the top of the front face, just to the right of cross-feed screw, was a rod that pushed in to operate a plunger pump to feed the same lubricant to the bed, cross-slide ways and cross-feed nut. Power feeds were selected by a push/pull button and positively engaged by a lever that allowed the feed to be stopped instantly regardless of how deep and heavy the cut was. A second push/pull button provided a means of reversing either feed whilst a knurled-edge dial, on the apron's right-hand face, allowed the operator to adjust the trip force that disengaged the feed as it was moving to either left or right - so providing a handy means of obtaining maximum accuracy when turning up to a shoulder length. A thread-dial indicator was fitted as standard. The carriage traverse handwheel could be pulled out to disengage it when power feeds were being used - a feature that was included from the very first models and almost certainly included because most examples are found fitted with a rapid carriage return, a vital fitting especially on the long-bed model. The compound slide rest was machined all over and fitted with taper gib strips that allowed a very precise fit to be obtained whilst giving far superior support in comparison with the cheaper "loose-strip" type. The 11-inch travel cross slide was especially wide and fitted with a cross-feed screw that could be adjusted to reduce backlash; although the slide was devoid of T slots and tapped holes - and so appeared, at a glance, to be incapable of mounting any accessories - the edges of the slide were machines to accept slide-on T-slotted and plain blocks that could hold a variety of items including hydraulic profiling units, and parting-off and other special tools. Able to be set over, the tailstock held a hardened and ground, 9-inch (229 mm) travel barrel with a huge No. 5 Morse taper. This was engraved with metric and inch graduations - though, surprisingly, considering its use on some smaller Colchester models, there was no zeroing micrometer dial on the feed handwheel. Constructed around two heavy cast-iron plinths, the stand had a usefully deep, slide-out chip tray. However, it offered no storage at all, in either plinths or centre section, even though this would not have been difficult to engineer and would have made life both easier and more productive for the operator. All but the most perverse would have been happy with the combination of feed and leadscrew combinations offered by the maker for the lathe was available with an English-pitch leadscrew with feed screw micrometer dial graduations in inches or millimetres, or with a Metric leadscrew. Standard equipment supplied with the lathe was fairly sparse and consisted of a 12.5-inch (315mm) 3-jaw chuck, a centre adapter to sleeve down the spindle nose, two No. 5 Morse centres, a simple slotted toolblock to accept one turning tool, driving plate, thread-dial indicator, spanners, oil can, an accuracy and inspection chart and a very useful combined instruction and parts book that showed the whole machine as a set of exploded component diagrams. Accessories included both a "Super-precision" ductile-iron 12.5-inch (315mm) 3-jaw chuck with a hardened and ground scroll as well as a cheaper 250mm 3-jaw chuck (but still in ductile-iron) with an unhardened scroll and for light-duty use only and of "limited accuracy". A 16-inch (405 mm) ductile-iron heavy-duty 4-jaw chuck and a half-depth body light-duty 12-inch (310 mm) independent 4-jaw chuck were also offered that, like the 3-jaw versions, were all specially made by the Burnerd company. A chuck guard, a telescopic taper turning attachment, a 17-inch (430 mm) faceplate for use on straight-bed lathes and 20-inch and 27-inch (500 mm and 685 mm) faceplates for gap-bed models, a zeroing micrometer dial on the carriage handwheel, 5-position indexing and single-position micrometer bed stops; a fixed steady with a capacity of 7 inches and a 3-inch capacity travelling steady both with plain fingers only; 4-way automatic ratchet-indexing and Dickson-type quick-set toolposts; dual metric and inch micrometer dials, a "longitudinal-travel" dial indicator, an Ainjest quick-threader attachment, T-slotted and plain blocks to locate over the cross slide and mount standard or quick-set rear toolholders, a high-precision, heavy-duty rotating centre, a low-volt light unit and a full-length splash back. The 40-inch between-centres Mascot 1600 was 98 inches long and weighed 40 cwt; the 60-inch lathe 118 inches long and 42 cwt; the 80-inch 138 inches long and 5359 lbs (2430 kg) and the 100-inch version was 158 inches long and weighed 5930 lbs (2690 kg). All were approximately 48 inches (111 mm) from front to back..
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