For many years Storebro Bruks Aktiebolag machine tools were manufactured in the village of Storebro, in the south east of Sweden, but the factory is now in the city of Varberg on the Swedish west coast. Today the firm, one of only two builders of lathes* in Sweden - the other is SMT based in Västerås - produce just CNC machines, although they can supply spares for almost any of their lathes, no matter how old. In line with many similar organisations the company has been split into several parts, the best known of which is now a successful builder of luxury motor yachts.
Since their founding in the early 1900s Storebro have produced over 50,000 machine tools 44,000 of which have been lathes, mostly of the larger, industrial kind although buyers were also found for 12,000 examples of a beautiful little general-purpose and toolroom lathes, the Ornmaskiner GK-185 and GK195. Amongst their more popular models were the S12A, S14AL and S16AL - the numbers (for the UK and USA export markets) denoting a centre height which was, in reality, just a faction of an inch less than the model number - and the S18, S20, S22 and S24 which, surprisingly, were sized so that their centre heights were a little greater than the model number. A clone of the South Bend 9-inch "Workshop" lathe was also manufactured, as was an example by another Swedish manufacturer, Blomqvist. All the company's traditional lathes, as would befit a Swedish-based firm, were carefully built from excellent quality materials and displayed many examples of thoughtful and ingenious design.
Massively constructed, the hardened beds of the S12, S14 and S16 models were 22 inches across and reinforced by full-depth diagonal stay ribs. The saddle was guided by one front and one rear V way, and also slid on one flat at the front. The tailstock was guided on the rear V but, unusually, used the same front flat as the saddle.
Robust but conventionally designed, the roller-bearing, 18-speed headstock featured hardened spur gears and pumped lubrication through an array of oil pipes. A 20 or 30 hp 1460 rpm motor, mounted on adjuster rails to the rear of the headstock-end leg, transmitted its drive through V belts and a double disc clutch - with an automatic spindle brake being brought into operation when the clutch lever was returned to its neutral position; any change of speed to an adjacent one could be made without stopping the lathe The maximum speed could be selected by the customer, at no extra cost, from a choice of either 600 or 950 rpm.
Hardened and ground, the 70 mm bore headstock spindle was 5.125" in diameter though its front bearing, and fitted with an L2 American Standard nose - although other fitting could be supplied to order - whilst, as a thoughtful touch (to aid the cutting of 2, 3, 4, 5, 6, 10, 12, or 15 threads) a graduated dial and indexing device was fitted to its outboard end. The spindle ran in high-precision cylindrical rollers bearings, with the end thrust taken by a ball race.
Completely enclosed and lubricated by the same pump that forced oil around the headstock, the screwcutting and feeds gearbox generated both metric and English threads - the change between them being simply accomplished by moving two levers; 81 inch threads were available from 1/8 to 60 t.p.i and 70 metric pitches from 0.2 to 120 mm.
With the gearbox set to cut metric threads a total of 72 longitudinal and cross feeds were available, from 0.05 to 1.8 mm (0.002" to 0.07" ) per revolution of the spindle in longitudinal feed and from 0.02 to 0.74 mm (0.0008" to 0.029") per revolution of the spindle in cross feed. With the gearbox set to generate inch threads the number of feeds was reduced to 45 with a range in longitudinal feed from 0.004" to 0.12" (0.1 to 3 mm) and in cross feed from 0.0016" to 0.049" (0.04 to 1,25 mm).
Changewheels driving the screwcutting gearbox ran on needle rollers and were supplied with oil from pumped system; the standard changewheel bracket could be replaced by one with adjustable centres, so allowing module, diametric and special threads - and almost any feed rate - to be set up using other changewheels. The power cross feed was so arranged that (in metric mode only) exact "pitches" could be obtained, making it possible, should it have been desired, to cut face spirals at the rate of 12 pitches from 0.25 to 20 mm per revolution.
Of strong, double-wall construction, the apron had all its shafts supported at both ends by bushes; both longitudinal and cross feeds could be set for automatic disengage against adjustable stops - and were driven through positive-tooth clutches with engagement levers positioned at the right-hand side of their cylindrical housings. The carriage drive could be instantly reversed by a lever on the face of the apron (and on the end of the power shaft by the screwcutting gearbox) - there being no mechanism to do this built into the headstock - whilst a hand-operated oil pump (the two operating wheels for which can be seen just below the carriage hand-traverse wheel) lifted oil from the base of the apron and distributed it both to the apron mechanism and the bed ways underneath the saddle. The cross slide was given a machined section at the rear designed, presumably, to be tapped and threaded to hold special tools; the feed screw was fitted with a thrust ball bearing and a double, adjustable nut which could be set so as to remove backlash.
The top and cross slides were both equipped with tapered gib strips - which offered both a more solid support and easier fine adjustment than an ordinary gib strip with "pusher screws" - and the feed screws fitted with traditional "balanced" handwheels.
*Swedish machine-tool makers no longer in existence include:
"Beijer" in Malmö (small lathes)
"Blomkvist" in Gotenburg (small lathes)
"Thule" (lathes, hobbers and grinders), "Torshälla" (Lathes) and "Köping" (Lathes) all in Malmö.
"Värnamo" (milling machines) and "Jochnick & Norman" (planers and hobbers) both in Värnamo
"Örn" in the village of Storebro (lathes) - this company joined Storebro Bruk at the start of 1960
"Erik Eriksson" in Torshälla (lathes)
"Sajo" in Värnamo (milling machines) and "Modig" in Virserum (lathes, drilling, and milling machines) - both still surviving as companies..