Of  50mm centre height the Model P was available in two bed lengths - the short PB1 and the longer "twin-support" PB2. Two headstocks were offered; the 8mm collet PH2 and the 10mm collet PH4 both able to take either draw-in or quick-action, lever-operated collet closers. The headstocks were fitted with split bronze bearings were designed for continuous running at 10,000 rpm - their ability to do this reliably being advertised by testimonials from satisfied custom The bearings had plain bores with a taper on the outside by which means a precise adjustment of the clearance could be made. A ball race was provided to take end thrust. The bearings were intended to run "warm" at all speeds with the makers suggesting that, if a machine was to be used continuously at high or low speeds, it would be worth adjusting the bearing clearance to suit. When the bearings were well used it was possible to dismantle them and remove a laminated shim (0.003") so that they closed up more when reassembled.
The tailstock on the "P" was normally supplied with a simple "push-action" barrel but a lever-operated device was an option and a screw-feed barrel was eventually offered as well.
Various arrangements of well-engineered rear and overhead drive countershafts were listed, most with a facility to power an "overhead" system to run toolpost-mounted, high-speed grinding and milling spindles. Later machines turned to a miniature V-belt drive (though the round belt was still effective) but for models of all years it was common (unless specially ordered for some specific task) for 9 speeds to be provided spanning approximately 236 to 5970 rpm. A 2-stage countershaft was also available that gave an 18-speed drive from 236 to 10,600 r.p.m. Because of the special work many of these machines were asked to perform, numerous variations on the standard countershafts have been discovered, obviously built with the aim of giving customer exactly the speed range most suited to their particular requirements.
In addition to the standard lathes Pultra also offered a number of "specials", one such being the thread-milling lathe Model NT59. This dipped into the accessories catalogue to employ a cast-iron base plate (B128) in conjunction with a 16" Long Bed (PB2), a 50mm centre height 10mm bore "geared headstock" (PH6A) with a 72 : 1 worm reduction, a guide frame (V124) and a "support" tailstock (PT6) that acted as a fixed steady. This version was designed for the accurate production of threads and worms and picked up the pitch from a "master thread" arranged (like those used in ordinary thread-chasing attachments), at the rear of the headstock, but cut the tread with a rotating cutter held in a live spindle (W123). The cutter could be adjusted to any angle either horizontally or vertically and the work held either in collets or (at a maximum length of 4.5") between centres using a drive plate

Developed as the 1590, 1750 and 1770 (the 50, 70 and 90 referring to the centre height in mm), the post-war models had clean, modern lines with a very high quality paint finish and an enclosed headstock pulley with the drive able to be taken downwards or rearwards to choice. These versions were to be the final development of the lathe though production continued, albeit in very small numbers, into the 21st century.  The first lathe of the new series, probably introduced during early 1947, was the 90mm (3.5") centre height Series 15. This was a very much larger and heavier lathe than other Pultras and, although styled along much the same lines, was constructed from entirely different components. However, so similar do the machines look that it is very easy, in some photographs, to mistake the large Series 15 for the smaller models. The 20 mm bore headstock spindle accepted collets with a Pultra reference of CJ.1 (20mm shank, maximum through-bore of 14 mm) whilst the grinding and milling attachments took the Type CE.1 collet with an 8 mm shank (maximum through-bore of 4.7 mm). Three different headstocks were available, all based on a common unit but categorised as "Standard (H.191D), "Special Toolroom" with "Locking Attachment" (H.191.A) and "Production" (H.204D) with, naturally enough, a lever-operated collet closer fitted as standard. Because the single drive pulley was overhung on the left-hand end of the spindle (though covered with an extension to the casting that made the assembly rather larger than it actually was) the belt could be changed on all versions without having to disturb the setting of the super-precision, plain headstock bearings. Driven from the recommended 3-phase, 1425 rpm, 0.9 hp motor with a 3-step pulley on its shaft (and via either rear or stand-contained countershafts) the 9 spindle speeds were: 135, 208, 350, 410, 633, 1068, 1258, 1936 and 3265 rpm. Although the 1750 and 1770 Models had headstock spindles that accepted only collets, or accessories carried on collets, the Model 1590 could mount chucks and faceplates using a fixing with a captive screwed ring behind the spindle-nose flange that resembled a miniature version of the American L Series long-taper key fitting employed on industrial-size lathes.
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The clean lines and superb finish of what became familiar to post World War Two users of miniature precision lathes as the Pultra Models "17/50 and "17/70" of 50mm and 70 mm centre height respectively.

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The cross slide had a travel of 4" inches (100 mm) and the top slide 3" inches (75 mm) - both considerably more than the 1.875" (48 mm) and 1.75" (45 mm) of the 1750 and 1770 models. The bed was 33.8" (860 mm) long and the length of its shears 31" (790 mm); it could accommodate 15" between centres (7" or 178 mm for the 1750 and 1770). On its optional (but essential) cast-iron base plate the total length was 35.75".
The 0.8125" (30.2 mm) diameter tailstock spindle was fitted with a No. 2 Morse taper centre and had a travel of 2.25"; both screw and lever-feed versions were available with the latter having the same CJ.1 collet fitting as the headstock. A micrometer-graduated collar was fitted to the spindle handwheel, marked in divisions of 0.02 mm.
Like the Series 15, the pair of Series 17 lathes had a very stiff, box-section headstocks with the drive pulley over-hung on the left-hand end of the spindle - again cleverly disguised by the comprehensive guarding. Besides being available for bench mounting, with a conventional countershaft, they were often fitted to an underdrive cabinet stand - the "Mardrive". This very heavy unit was, in reality, a beautifully-made industrial sewing-machine cabinet suitably modified by its Stockport (Cheshire) makers for lathe use. It held a multi-speed countershaft unit (part A.890a) neatly inside its left-hand compartment with a foot pedal, positioned between the stand pedestals, to operate a motor-mounted combined clutch and brake unit. Although this choice of stand might seem strange, it was actually a very sensible choice for, if you have ever examined industrial sewing equipment, you will be aware that, due to the daily hammering it suffers at the hands of piece-work operators, everything has to be every bit as well made as the finest precision machine tools. The Mardrive cabinet for the Series 15 was given the part code M.812/15 and for the 1750 and 1770 lathes M.812/17
Identical in all but the thickness of headstock and tailstock casting - and the depth of their toolposts - the 1750 and 1770 both used 10mm collets in the headstock spindle - a 7/8" diameter 26 t.p.i. thread on the spindle end being for the use of a protective sleeve, when the job included cutting close to a collet face, or to mount a closer for large disc "chucks" to pull back against - the  expression "chuck" referring, in watchmaking circles, to a collet. Four types headstock were available for the 1550 and 1750: the 'Standard Duty' and 'Heavy Duty' were both set to run at an average speed of 3000 rpm with a maximum of 6500 rpm) - the "Large Bore" was limited to 5100 r.p.m. whilst the "High Speed" could reach and maintain 12,000 r.p.m. reliably.  Although, in reality, all models could be provided with any version of the headstock, the 50mm lathes were usually advertised with a choice of "Standard" or "Heavy Duty" types whist the 70mm version was listed as being fitted with just the "High Speed" unit.
Two bed lengths were produced: a rare 14-inch that stood on a single headstock-end foot and a more common double-foot 18-inch; these gave, respectively, 3 and 7 inches between centres. When mounted on the common-to-both models cast-iron Chip Tray Base Unit (B214), the overall length was 18.75 inches and the weight between 50 and 64 lbs (22 to 29 kg).
Three varieties of tailstock were produced for all models: each used an identical standard body and could be fitted with a spindle that was manually positioned or operated by a screw or lever. The screw-feed and "push-feed" versions had either a CF.1 collet fitting or a No. 0 Morse taper and the lever-feed version just the collet-holding bore. The screw-feed spindle carried a zeroing micrometer dial and, because the various components were precisely made, it was possible to buy all three types and use them interchangeably on a single casting.
As with most precision lathes, the Pultra could be fitted with a useful range of expensive accessories to enable almost any precision machining process to be carried out: high-speed grinding and milling spindles to use in both the toolpost and on a vertical slide; fixed and travelling steadies; a headstock-mounted dividing attachment; tilting and fixed handrests with wide and narrow T-rests; a miniature saw table; 4-way, single and rear toolposts, a filing rest, adjustable roller rest and raising blocks for the headstock, tailstock and toolpost. Alone amongst the models the 1590 could be equipped with a screwcutting and feeds drive to the top slide; a well-engineered fitting with a commodious changewheel bracket this unit provided an unusually wide range of pitches. The compound slide rests, almost unchanged from the first examples made in the 1940s, could be fitted with any combination of lever and (ultra-fine) screw feed to either the top or cross-slide. At the height of production a vast range of standard, disc, disc, bell and nose-recessed collets and the usual miniature fittings - die heads, box and knee tool holders, drill and tap holders, etc. were all catalogued.  Today the accessories are highly sought-after, especially the collets, milling slides and boring and grinding heads - whilst even the previously neglected production items will find a home in the workshop of a Pultra collector.
If you have a Pultra Series 15, a Pultra Watchmakers' lathe or a Pultra grinder, please do contact the writer..
Tony Griffiths

Pultra 17/50 & 17/70 countershaft unit with a sewing-machine type clutch on the motor's spindle and an integral overhead drive to a high-speed milling and grinding head mounted on a vertical slide.

1700 series lathe fitted to the heavy and well-made "Mardrive" cabinet stand with foot-operated combined clutch and brake unit.