Continued:
The 15/16" (35 mm) bore headstock spindle ran in Gamet "micro-precision" taper roller bearings (made by another company in the Colchester group) with the lower part of the speed range obtained through hardened and ground gears. Because the high-speed range was directly by belt, and the comparatively short and rigid spindle so well supported, the lathe had a well-deserved reputation for being able to produce unusually smooth surface finishes. An American-type D1-3" Camlock nose fitting was used, that allowed the lathe spindle to be safely reversed at high speed, and the spindle was sleeved with a hardened 4 Morse taper short sleeve bored to accept a standard No. 2 Morse taper centre (this fitting is often missing, and expensive to replace - though sometimes cheaper replacements are available). Unfortunately, chucks with an integral D1-3" mounting are pricey to manufacture and it is often cheaper (although with only a little saving) to mount a replacement chuck on a new Camlock backplate. Certain precautions are necessary when mounting new D1 accessories on the spindle nose and it may be necessary, in order to achieve maximum grip, to re-set the Camlock studs within them - it is absolutely essential to read the maker's instructions on this point if you are unsure.
All Chipmasters were fitted with a full screwcutting gearbox that offered a greater range of threads than the Bantam. The drive to the gearbox was by changewheels for screwcutting or, for extra-fine feeds, via a V-belt on early lathes and a toothed belt (for a more positive drive) on later models. A lever on front of the headstock - annotated with a belt and gear symbols - selected the appropriate drive. For many years only an Imperial (inch pitches) gearbox was offered, with conversion gears to cut metric threads. However, from the end of 1970 onwards a version with a dedicated metric gearbox was offered. At extra cost the box could be provided with inch-pitch conversion gears, the set comprising: 20t, 24t, 28t, 30t, 36t, 42t, 44t, 46t, 52t, 56t, 57t, 60t, 65t, 69t and 70t. The Imperial box can be recognised by its sliding lever control with indent positions (outboard of the box to the right) whilst the metric box was similar to the unit as used on the Bantam with a joy-stick control in addition to levers. At the end of 1970 an "all-metric" version of the Chipmaster became available and carried the identification "Continental". Fitted with the appropriate translation changewheels English to metric and metric to English screwcutting conversions were possible.
Once in private hands, after hard industrial service, the Chipmaster could suffer problems connected with the drive system; the variator has always been enormously expensive to overhaul and, if it started to produce any untoward noises, they would rapidly assume the volume made by a tumble-drier filled with bell bearings - and if you didn't stop using the lathe, that's more or less what the variator turned itself into. If the variator on the lathe you are considering works smoothly (they are rarely silent), and you decide it will be worthwhile to swap the motor to a single-phase unit, you will find changing it an uncomfortable task. Fortunately, thanks to the wonders of modern technology, a simple solution is at hand - fit an electronic speed-control "inverter". Once in place these units then allow two means of varying the spindle speed: electronically and mechanically - though in practice you will probably find that the electronic method is all you need most of the time. If, however, the mechanical variator on the lathe you are inspecting appears to be faulty, don't worry, you don't really need it. Dump it into the scrap bin (take it apart first and have a look, just in case) and couple the motor up to the inverter you were going to buy anyway. Inverters, unlike simple capacitor-based "converters", provide a variable-output frequency (giving variable-speed drive) and hence obviate the need for any mechanical speed-changing device. They are also inherently reliable - and prices keep falling. The clutch fitted a standard to all Chipmasters not only makes the machine much more pleasant to use but also gives any 1-phase conversion (or electronic control, system) a much easier time.
Some few years ago a friend bought a new, still-crated Chipmaster which had lain forgotten in a store (that's another story). He removed the variator and arranged for the spindle to be driven directly from the electric motor through a 3-phase to 3-phase variable-speed electronic controller. He over-rated it, to give 4000 rpm, and rigged the DC injection braking to make it stop it in a couple of rpm or so (the first time he tried it the motor stopped dead, but the inertia of the rotating parts stripped the drive belt of its teeth.). This machine ran reliably for years, turning out thousands of critically-dimensioned and beautifully-finished aero-space components. For some export markets the Chipmaster was marketed wearing Harrison badges as the Model 10-AA.
Although it took Colchester a little time to get the drive system right, the rest of the lathe remained essentially unchanged throughout its production life - proof that the original design was well thought out and the concept - a machine that could be marketed as a lathe suitable for toolroom, production and general workshop duties - was absolutely right..

The bed, hardened to order only at first but later fitted as standard, was particularly stiff with chip clearance through elliptical holes that passed to the rear.

Early Chipmasters had a drive to the Matrix clutch by three V-belts and to the screwcutting and feeds gearbox by both gear and V belt. In this publicity picture the V-belt drive from variator to Matrix clutch has been air-brushed out.

Chipmaster Screwcutting Gearbox. Lathes with English threading used a different gearbox to those fitted with Metric screwcutting (below); the English box can be recognised by its sliding lever control (as above) the metric box was the same unit as used on the Bantam and had a joy-stick selector (see below). Some "all-metric" Chipmaster lathes carried the identification "Continental". Both the English and metric gearbox could generate, with appropriate translation changewheels, the other type of thread.

The 15/16" (35 mm) bore headstock spindle ran in Gamet "micro-precision" taper roller bearings (made by anther company in the Colchester group) with the lower part of the speed range obtained through hardened and ground gears. Because the high-speed range was direct by belt, and the comparatively short and rigid spindle so well supported, the lathe had a reputation for being able to produce unusually smooth surface finishes. An American-type D1-3" Camlock nose fitting was used that allowed the lathe spindle to be safely reversed at high speed. Note the toothed pulley, fitted to a spline on the pulley and used to drive the spindle directly on the high speed range.