1908 Model with the first compound slide rest. Originally fitted with full-circle handwheels it quickly reverted to the more traditional cranked type shown in the picture below. An interesting comparison can be made between this model and a  contemporary Flather lathe of similar size.CLICK HERE  for more pictures and information about the original Drummond model

Drummond B Type circa 1912--1921. In reality, a completely new model incorporating much fresh thinking about how a small lathe should be constructed. For a series of detailed photographs of this type, click HERE

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For the first ten years of production Drummond retained the basic structure of their original small flat-bed lathe largely unchanged; however, every twelve months or so, some small but significant changes were made to the specification and these alterations can be used to date early machines with reasonable accuracy. A more detailed look at the first lathes, their development and alterations made over the years, can be found HERE.
Although Drummond may have considered a developed version of the early lathe - one meeting that criteria has been found in Australia - in 1912 Drummond introduced what was, in reality, a completely new model  that bore the official title "B Type". The bed was made much heavier and stiffer, with the saddle thrust taken on a vertical surface on the inside of the front way, a bar cast between the headstock bearings above the spindle pulley to improve rigidity (and reduce tool chatter) and the spindle-thread size was increased in size from 3/4" to 1". The leadscrew was moved from the middle to the front of the bed and the dog clutch fitted with a useful pre-set automatic throw-out facility. The changewheel arm (banjo) became V-shaped and allowed wider spacing of the changewheels - and hence the opportunity to use larger gears and make the carriage travel more slowly on its finest feed. Interestingly, the same original error - of trying to employ a cheap, single-slot changewheel arm - was made by South Bend on the introduction of their inexpensive Model 5 lathe in late 1931). As on all small Drummond lathes (including the much later Myford M-Type) the changewheels were 14 DP with a 14.5 degrees pressure angle; today, unfortunately, the standard pressure angle is 20 degrees so "off-the-shelf" gears will not match satisfactorily; if a new gears are required they have to be specially made. To connect the gears in pairs for a compound train each gear carried a pin and a pin hole; the pins are seated in tapered holes and, if driven out the wrong way, will fracture the gear. To go with the rest of the improved machine the tailstock was completely redesigned and fitted with a guidance similar to that of the saddle - but the solid barrel was retained. The original style of round-rope was left in place to complete a few more years' service, but the stand was entirely different and made much heavier and stiffer - however the original holes, that allowed belt passage on the lowest speed of the earlier models, were still retained.
In 1915 a thick gib 'block' was fitted at the front of the saddle in place of the original gib strip at the rear - which meant that tool thrust was now taken against a solid surface - not a strip of metal supported at three places by pointed screws - and the rigidity of the saddle-to-bed fitting enormously improved.  A larger cross slide was also incorporated that had, at least in some cases, a micrometer dial fitted to its feed screw--though whether this was a standard fitting, or an accessory, is not clear. The true centre height was also increased to 35/8"
In 1916 the Mk. 1 "B.S. Type" was introduced for Admiralty use with a range of modifications to ease the difficulties encountered when turning in a rough sea. It was closely based on the standard "B Type" machine but fitted with a power-feed apron with both longitudinal and cross feeds taken from a shaft fitted below the leadscrew and geared to its left-hand end. A saddle traverse by hand-wheel to a rack and pinion was also included (but not the contemporary standard lathe) and a tumble-reverse mechanism fitted to the changewheel drive. This was neatly fitted to the slotted bracket on the headstock front that normally carried a stud to mount the extra changewheel required for left-hand screwcutting; when the tumble reverse unit became available on the B.S. it also entered the accessory lists for the standard machine. "B Type" lathe beds of the era can be identified by the "pads" cast onto the front face of the bed to accept the power cross feed layshaft assembly. On the Mk. 1 BS the power-feed selector arm worked across the front of the apron whilst on much more common Mk. 2 it was positioned to hang downwards and indent into the underside face. There is no evidence that the BS was made available for civilian use, it being entirely absent from Drummond catalogues of the time.
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Getting stronger: the penultimate version of Drummond's small lathe the "new-for-1921" M Type. This version lasted only 4 years before being replaced with an improved model. More pictures of this variant here.

Continued: Drummond 1921
In 1921 Drummond again improved their smallest lathe and renamed it the M Type, though this particular version, to be altered again in 1925, was to have the shortest run of any model (save perhaps the original model produced in 1902 and first modified in 1904). The aim of the new alterations was to improved rigidity and resistance to tool chatter and the main changes focus on the headstock where a greater mass of metal was used, the futile over-arm brace removed and the flexible and poorly supported system of using two flat surfaces simply bolted together (buy which means the headstock could be rotated slightly) was abandoned. In its place was a positive location with a tongue on the base of the headstock located against a matching vertical surface on the bed - the whole assembly clamped down firmly with four bolts. Larger spindle bearings were employed the adjustment of which reverted to an earlier Drummond design where a large ring, screwed onto the end of the bearing itself, pulled it into the tapered headstock housing and provided a means of accurately adjusting the clearance. The design was actually more complex than at first appeared and required careful manipulation of "drilled oil bolt" that acted, via a wedge, to expand the bearing fully into its housing.  As a final touch a proper ball-bearing thrust race was engineered to fit against the inside left-hand end of the spindle. As an aid to heavier rates of metal removal a long-needed, three-step flat-belt drive replaced the by-now hopelessly inadequate small-diameter round "gut" drive previously used . The spindle nose was again, as in 1912, upgraded and now fitted with a 1" x 12 t.p.i. thread backed by a 11/8" register designed to improve the rigidity of screwed attachments. The backgear ratio was changed from 20:60T to 22:66T and engaged by rotating an eccentric shaft instead of sliding into place. In place of  having to reach for a spanner to disengage the 66t bull wheel from its embrace with the belt pulley, a cleverly designed "ramp" (that acted as a cam) was machined into a plate on the front of the gear. If everything was adjusted to slide easily, a swift push by a gnarled thumb against a knurled-edge knob was sufficient to persuaded the close-fitting engagement pin out of mesh with the pulley-flange. To engage direct drive the backgear was swung away and the knob merely moved slightly in the other direction - when a spring on the pin returned it automatically to engage with the pulley. The writer spent some time using one of the lathes and the speed with which backgear could be engaged and disengaged was a delight. The No. 1 Morse taper tailstock was also further increased in strength and the barrel diameter increased from 3/4" to 7/8". The previous rather crude screw-in barrel clamp gave way to a much more elegant and efficient "cotter" or "internally-split" locking device and some machines (but not, surprisingly, all) were given a hollow barrel to solve the problem of how to remove centres and chucks.
Whilst the T-slotted cross slide casting was unchanged, the top slide (apart from the early-pattern clog-heel toolpost) was all-new: its feed screw was off-set to the side in order to provide a longer and slower-wearing nut and allow the tailstock to come right up to the right-hand face of the cross slide and its base given an improved (though still hard-to-read) degree-graduated scale on an inserted brass plate; the cross-slide feed screw handle was modified to have two finger grips and given a zeroing micrometer dial.
Although the changewheels remained unchanged their studs, instead of being fitted with slow-to-remove screw-on knurled-edge finger nut retainers, were given a new design of (patented) push-in "spring" type  - a design that was to be used until the end of production. On previous models the changewheel banjo arm had always been held in place by a crude through-bolt that simple ran up against the mounting boss, a design that made it difficult to get enough grip to stop the arm being moved sideways when heavy cuts were taken. This was now supplemented by extending the arm in a slotted curve at the back through which passed a stud and nut to ensure that it simple could not move no matter how great the provocation. The treadle-driven flywheel was balanced and ran on a ball race, as did the "pitman" driving link, both changes helping the operator to maintain a good speed with less effort.
More pictures of this model can be seen here.
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Final development: the Drummond M Type of late 1924 to 1943 with a leadscrew clasp nut and rack-and-pinion drive (20DP) to the carriage. Interestingly, a T-rest for hand turning was still considered by the makers to be an essential extra and included as standard with every lathe. This model was the first to have the simple but effective "Norman Patent" quickly-adjustable toolpost.
Drummond 1924
Further important changes were made in late 1924 that greatly improved the functionality of the lathe; these included a 'dis-engageable' leadscrew nut - a rather awkward assembly formed from a substantial bronze "swinging arm" and located by a spring-loaded plunger on the left-side of the apron face. The nut was only a "half" type, the upper portion consisting of an adjustable, plain, half-round bronze thrust pad retained by a massive bronze nut against the inside face of the apron and the carriage further improved by the addition of a direct (though unfortunately high-geared) rack-and-pinion feed as originally fitted to the power-cross feed BS model.  The top slide was thickened towards the rear, where it supported the feed-screw cross plate, and an enormous improvement made by incorporating, as standard, a quick-set toolholder of the "Norman Patent" type. The "Norman" was a simple but highly effective dsign and consisted of nothing more than a split hardened block, with a broached square tool hole, arranged to slide up and down and clamp to a 1.25" diameter pillar cast integral with the upper section of the top slide. The cast-in post was also  tapped down its centre - for two purposes: to retain the maker's milling slide and, later, to provide a means of clamping down a 4-way toolpost. Around the same time a long-bed version of the lathe was introduced - and also made available to the armed services in a (now very rare) BS power-cross-feed version. Although further very minor modifications were made this was the essentially the form in which the lathe continued until, in 1943 on orders issued by the Machine Tool Control Board, the Myford Company were instructed to take over production for the remainder of World War Two - the earliest known examples from the Myford Factory being stamped 1943 and with modified versions still turning up from time to time. The last versions were built by Myford in the late 1940s with the final machines, which all seem to have been long-bed types, assembled from spares (according to the data on the changewheel cover) as late as 1954.  Another small Drummond, made especially for the impecunious enthusiast, was the "Little Goliath" a very simple, not to say crude lathe, built down to a price and evidently, by the few surviving, not a complete sales success.
A very rare Model M has recently come to light, a geared-head version dated 1940, which bears all the hallmarks of either a pre-production prototype (or a machine modified by an enthusiast) and appears to have used the bed, tailstock, leadscrew and cross slide of the standard lathe, but with an entirely different headstock and apron. 
More information about the earliest Drummond models can be found here and a continuation of this article here.
Tony Griffiths