The head was constructed so that a front element (that holding the spindle) was arranged to slide on a back section (the moving section always being fully supported within its ways), the drive being by a screw and nut flooded with oil from a pressure supply (a scavenge pump being provided to prevent leakage). Head locking used a particularly effective clamp - a lever acting to move a tapered gib strip that clamped the chosen setting tightly.

Fitted with a No. 50 INT nose and carrying a large drive gear designed to add inertia, the spindle was manufactured from a nickel-steel forging, ground all over and ran in Timken taper roller bearings at the front and centre with a precision roller race at the rear.

Automatic backlash eliminator - at first an option and later a standard fitment. The mechanism was contained in a single housing and comprised two separate feed nuts, each machined on its outside with teeth that meshed with a rack. The racks were arranged to sit at each side of a spur gear that, when rotated, moved one rack forwards and the other backwards - so forcing the nuts to rotate slightly in opposite directions and so take out any play between nuts and screw.