Joint forming devices

A device for forming a joint between two members, said device comprising a tightening element having an axis of rotation to be fitted to one said member and a fastening element having a longitudinal axis to be fitted to the other said member, said fastening element comprising of female part to be at least partially received in a recess in said other member, and a male part having an expander region at a first end portion thereof adapted to be received in said female part, said expander region serving to expand said female part upon axial movement of said male part relative to said female part in a first direction to anchor said female part in said recess in said other member, said male part having at a second end portion thereof at least one engaging surface cooperably engageable with a respective arcuate camming surface of said tightening element whereby rotation of said tightening element in one sense about said axis of rotation thereof causes axial movement of said male part in said first direction towards said axis of rotation firstly to cause said female part to be anchored in said recess in said other member and then to pull said other member towards said one member and thereby cause the joint formed between said two members to tighten, each said arcuate camming surface having a continuous lengthwise profile having a predetermined curvature in which the radial distance of each said camming surface from said axis of rotation of said tightening element decreases at a predetermined constant rate substantially over the length of said profile, whereby rotation of said tightening element in said one sense causes said male part to move axially in said one direction at a rate which is substantially constant relative to said rate of rotation of said tightening element substantially throughout the range of said axial and rotational movements to produce a progressive, substantially linear tightening action for said joint, and said device further comprising means for resisting rotation of said tightening element about said axis of rotation at least in the sense opposite to said one sense.