Dean Smith and Grace lathes of the '30s and 40s had a large motor flange-mounted against the left-hand face of the machine. At first the headstock control levers were a mixture of long steel levers with shaped ends and shorter bars tipped with knobs; later models, probably under pressure of war-time production, economised with the exclusive use of knob-tipped, straight bars. The screwcutting arrangements included a simple gearbox, to give six pitches and six rates of power sliding and surfacing feeds for each setting of the changewheels and a universal multi-change gearbox with a full range of threads and feeds.  Models designations were: 7-inch centre height Models 4AN and 4AR; 8.5-inch centre height "light-type" Models 4AB and 4ABR; 8.5-inch centre height standard machines Models 4BN and 4BR; 10-inch centre height "light type" Models 4BC and 4BCR and a 12-inch lathe, the 4BD and 4BDR--the latter disappearing from the lists during World war 2. All types were made in a variety of bed lengths, as follows:  6, 8 or 10 feet long beds for the for the 7-inch and light 8.5-inch and 8, 10, 11 or 16 feet for the two larger types. The beds of the 7 and 8.5-inch models were 12.25 inches wide (312 mm) and that of the 10 and 12-inch models a little over 16 inches (406 mm). The 7-inch and light-type 8.5-inch models had 5 h.p. motors with 12 speeds from 11 to 490 r.p.m and the standard 8.5 inch, light 10-inch and 12-inch versions 10 h.p. motors with twelve speeds from 19 to 418 r.p.m - those these might well have differed according to a customer's preference..