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Stewartry Lathe

Page 2   Page 3   Page 4 - Stewartry Lathe as Found


With only one known surviving example - and hence almost unknown - the  2.125" x 7" (50 mm x 178 mm) Stewartry lathe was manufactured by G.B. Montgomery Mfg. of Montrose Avenue, Hillington, Glasgow W.2. Unfortunately nothing can be found of the Company's history, not even for how long they made the lathe - a model clearly aimed amateur and almost certainly made in the 1940s or early 1950s. However, from it design and appearance, this was a machine appearing to have taken inspiration from the professional models by such as those by Boley, Lorch, Leinen, Pultra, IME and similar highly-regarded manufacturers - and hence would have been targeted at the better-off.
Of typically English design, the bed had a finished-ground flat top, 60-degree dovetail slides to guide the carriage and a central slot with vertical sides to locate the tailstock. The saddle-to-bed gib strip was adjusted by no fewer than five screws but, unfortunately, was positioned at the rear, on the saddle's thrust face, instead of at the front; however, for the small cutting forces involved with this size of machine the design was perhaps a forgivable short cut. The rest of the carriage showed considerable attention to detail: the full-length cross slide had a travel of 2.5 inches and carried two T slots (so that it could be used as a simple boring table with the top slide removed) and, on the 2.5-inch travel top slide, an "integrated" 4-way toolpost; the feed screws were fitted with proper "balanced" handles (as were all the lathe's operating levers) and zeroing micrometer dials.
Made from case-hardened mild steel (ground all over), the 3/8"-bore headstock spindle ran in what were, in proportion to the rest of the lathe, a generously-sized double-cone lead-bronze bearing - of rather unusual design with both a shallow and steep taper -  at the front and a parallel bearing at the rear - both lubricated through wick-feed oilers. In order to surround the front bearing with as greater a mass of metal as possible the headstock pulley was arranged with its smallest groove (17/16" diameter) towards the front. The maker's simple but neatly designed combined countershaft and motor plate was bolted to the bench with studs that passed through vibration-absorbing rubber bushes, this allowing the use of cheaper fractional HP motors (a 1/6 to 1/4 hp 1425 rpm "Hoover" was recommended) without the superior and very effective built-in resilient mounting of the Brook and Brook-Crompton type. A solid steel vertical post carried a height-adjustable housing with a bearing supported shaft with, on one side the main spindle drive pulley and, on the other a smaller 3-step pulley to drive toolpost-mounted high-speed milling and grinding heads. With a double-step pulley on the motor driving a matching one on the countershaft, 6 spindle speeds were available of: 160, 310, 600, 900, 1700 and 3300 rpm. In line with the contemporary "take-care-of-yourself" attitude, the makers did not see fit to offer any sort of guarding for the belt runs or changewheels.
Continued below:

2.125" x 7" Stewartry Lathe

Continued:
Carried on a double-slotted bracket, the changewheels were, at 20DP, of rather too coarse a pitch for the size of lathe and consequently it was impossible to get a really fine feed along the bed under power. Even if the owner had made longer mounting studs and fitted a compound gear train to give the greatest possible reduction, the slowest feed would have been approximately 0.0064" per revolution of the spindle, about 4 times too fast. The 0.1-inch pitch Acme-form leadscrew was fitted with a graduated dial and balanced handwheel at the tailstock end of the bed and a dog clutch at the other; it ran through a solid bronze nut on the carriage and, because it could not be disengaged, was fitted with a neat dog clutch whose ball-ended operating handle was pivoted on the leadscrew's headstock-end bearing housing.
Properly designed with an eccentric bed clamp (operated by a permanently-fitted  handle), the tailstock had a double compression lock on the 2-inch travel, ground-finish No. 1 Morse taper spindle - the latter moved through its lapped hole by a lever whose operating arm was of such length that great sensitivity could be exercised when using very small drills.
From the late 1940s onwards the impecunious amateur enthusiast, in the market for a well-made screwcutting lathe of around 2-inch centre height, had little to choose from that was not well beyond his pocket; most cheap machines fell into the Sheffield-made Adept, Super Adept and Flexispeed class: these were simple, plain-turning lathes - priced at between 5 and 10 -  that were useable but very lightly built and frustrating in their limitations. While the very well specified backgeared and screwcutting Haighton and Grindturn "Cadet" might have appealed, this cost 44 : 15s : 0d ready to run (only 7 : 2s : 6d less (25%) than a 3.5" x  20" Myford ML7), and could only be afforded by the better paid. Although a basic Stewartry was listed at just 20 (with a chuck, countershaft and motor extra) judging by a lack of surviving examples, it can have found few buyers. Unfortunately all makers of these shrunken replicas of larger lathes had failed to see what their customers really needed, a miniature multi-function machine, and it was not until the arrival of the radically different Emco Unimat in 1953 that their needs were met. The Unimat was a lathe that, while very small, was highly versatile and could be converted into a miller-driller by simply repositioning the complete headstock assembly (and its integrated motor-drive system) onto a vertical post. It was also adaptable, by the addition of reasonably-priced and cleverly-designed accessories, for a variety of woodworking tasks including sawing, fret-sawing, jig-sawing, planing, routing and sanding. At 27 in the UK, and backed by a determined marketing effort with affordable credit terms, the Emco finally sealed the fate of backyard engineering companies making worthy but essentially old-fashioned miniature lathes for the amateur. If any reader has a Stewartry lathe the writer would be interested to hear from you..  More on Page 2Page 3 and Page 4

Stewartry lathe with the maker's combined 6-speed countershaft and resilient-mount motor plate

In order to surround the front bearing with as greater mass of metal as possible the headstock pulley was arranged with its smallest (17/16" diameter) groove towards the front. The changewheels were of far too coarse a pitch and, even when set up as a compound gear train to give the possible greatest step-down reduction, still drove the carriage along the bed too quickly.

The full-length cross slide had a travel of 2.5 inches and carried two T slots (so that it could be used as a simple boring table) and, on the 2.5-inch travel top slide, an "integrated" 4-way toolpost; the feed screws were fitted with proper balanced handles and zeroing micrometer dials. Note the 5 bed-to-carriage gib strip adjustment screws along the rear (thrust) edge of the saddle casting; ideally, these should have been at the front to allow a "solid" metal-to-metal contact at the back.

Maker's combined countershaft and motor plate. Bolted to the bench with studs that passed through vibration-absorbing rubber bushes this unit  allowed the use of cheaper fractional HP motors without the superior and very effective built-in resilient mounting of the Brook and Brook-Crompton type (a solid-mount 1/6 to 1/4 hp 1425 r.p.m. "Hoover" was recommended). With a double-step pulley on the motor (driving a matching one on the countershaft) 6 speeds were available of: 160, 310, 600, 900, 1700 and 3300 rpm.
On the opposite side to the main spindle-drive pulley was another small 3-step one to drive toolpost-mounted high-speed grinding and milling heads


Page 2   Page 3   Page 4 - Stewartry Lathe as Found

Stewartry Lathe
email: tony@lathes.co.uk
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