A conical bearing interface (16, 17) on the nut (10) and the washer (18) is advantageously substantially 20 to the radial plane of the nut.

Rotation of the shaft rotates the nut causing the nut (and associated sub-base (15)) to move up and down the screw.

The two portions of the nut are retained in the radial direction by a coaxial cylinder (24).

At the first stage all bolts / nuts have to be tightened by hand.

My stopper had one hole so I found an eye bolt and appropriate nut.

Further, each of fixture elements in turn reaches on one whole revolution, and transition from one bolt / nut to another has to be carried out in a diagonal order (cross-wise).

Further, each of fixture elements in turn reaches on one complete revolution, and transition from one bolt / nut to another has to be carried out in a diagonal order (cross-wise).