I am fortunate enough to have an Ainjest rapid threading attachment fitted to my Colchester Student lathe which makes screw-cutting as easy as feeding buns to elephants, as a dear old colleague of mine used to say. Being an admirer of the late Jack Radford, I have recently been considering making his Six-Position Saddle Stop for my Myford ML7-R which works in a similar way but disengages the lathe's own half-nuts, rather than an auxiliary half-nut as on the Ainjest. Could I enquire as to whether anyone has made and used this particular attachment and how effective it is? The design calls for a modification to be made on the apron and I don't particularly want to 'butcher' the machine if the overall end result turns out to be hardly worth the effort. Radford himself admits that there is small delay in the tripping of the mechanism equating to about 0.125" of saddle travel but I think this could be eliminated in practice when setting up for arresting the movement as with the Ainjest. Something in the back of my mind tells me that Martin Cleeve also designed a similar 'gizmo'.