In order to give the standard lathe a power feed, and the possibility of screwcutting, a very-well constructed unit (Provisional Patent 10988) was made by Aird & Company of Brighton. The assembly plugged into the end of the bed and was located by a single bolt, tapped into the underneath of the bed where it passed through the headstock casting. Some means of quickly engaging and disengaging the drive was required, and the solution, eminently simple and practical, was to arrange for a spring-loaded plunger to engage the drive, via a half-dog on the end of the centre shaft; to keep the cut going however, the knurled wheel had to be held in, releasing it caused the drive to immediately stop. The screwcutting attachment provided by the makers included a well-engineered positive dog clutch, operated by a lever positioned between the end of the bed and the banjo arm.
By using combinations of the three slots on the end bracket, and the two supplied studs, it was possible to obtain a multitude of drive ratios to the leadscrew - however, screwcutting would have been difficult without a backgear assembly, and only the use of a modified countershaft would have reduced the spindle speeds to a level where a thread could be safely generated.
To fit the assembly a longer pain headstock spindle was required to carry the drive gear, and this was included in the