Early Smart & Brown Model A Mk 1 4.5" x 18" (118 mm x 508 mm) circa 1947 - 1957

Like all the larger toolroom S & B lathes the speed-change gearbox of the model A was mounted inside the base of the cast-iron cabinet stand and the drive transmitted smoothly to the plain-bearing headstock by a flat belt. The apron contained an automatic oil pump whilst the headstock bearings, and gear drive to the screwcutting gearbox, were lubricated by a hand pump - the plunger handle of which can be seen protruding through the headstock cover.
The maximum collet capacity was 0.75" (19 mm), the spindle nose was 1.75" x 8 t.p.i and the headstock bore 63/64" (25 mm). The centres were No. 2 Morse taper, the twelve spindle speeds ranged from 39 to 1430 rpm. and the machine weighed 1736 lbs.
Direct-fitting spindle collets are the Crawfor dType 2804, these have a plain diameter of 0.984", a length of 3.625" and a collet head (closed down) of 1.310". Another collet that fits, though the maker is not know, is stamped 1266.
Pictures showing details of the Model A are lower down the page.
One important point about early versions of the Model A concerns the sometimes-encountered difficulty of changing speeds - this being done by a 3-position quadrant lever, on the front face of the stand, connected by a shaft to a three-speed gearbox mounted inside the cabinet. The design of this mechanism is faulty, the shaft connecting the lever to the gearbox being fixed rigidly in position on the lever, but free to move up and down with gearbox motor-support plate. As the latter is adjusted up and down to set the tension of the headstock drive belt, the shaft is deflected out of line making gear section difficult - or even impossible. The solution? Make sure that the belt is kept as short as possible; this means that any necessary adjustment of the belt's final tension is reduced to a minimum and hence shaft misalignment greatly reduced. As short-cut, if gear changing is difficult, before moving the quadrant lever, use the belt tensioning lever to slacken the belt, change the speed and then re-tension. Lathes.co.uk can supply the correct drive belt, made from either this or this.
Phone 01298-871633 for more details of belts and their fitting

Smart & Brown Model A Mk 2 4.5" x 18" (118 mm x 508 mm)
The Mk. 2 Model A, announced in 1958, was initially supplied on the original style of stand (above). By 1961 it had been provided with improved electrical controls and fitted to a stand with much cleaner lines. The Mk 2 was a thoroughly reworked machine with gear-selection mechanism and the apron and tailstock being almost completely redesigned.

A rare glimpse inside the factory's development department as it was in the summer of 1968. Although little can be seen of the machine tools, the fact that each member of staff appears to be wearing what is, no doubt, a crisply laundered white shirt together with a tie, tells you a lot about the standards of the era.

One important point about early versions of the Model A concerns the sometimes-encountered difficulty of changing speeds - this being done by a 3-position quadrant lever on the front face of the stand connected to a three-speed gearbox mounted inside the cabinet stand. The design of this mechanism is faulty, the shaft connecting the lever to the gearbox being fixed rigidly in position on the lever, but free to move up and down with gearbox motor-support plate. As the latter is adjusted up and down to set the tension of the headstock drive belt, the shaft is deflected out of line making gear section difficult or impossible. The solution? Make sure that the belt is kept as short as possible; this means that any adjustment of the final tension is as small as possible and so the shaft misalignment minimised. As temporary short cut, if gear changing is difficult, before moving the quadrant lever, use the belt tensioning lever to slacken the belt, change the speed and then re-tension the belt.