Making a steady rest

[Mayhem]

Thanks Bill,

Looking at it I am guessing E and G are fastened together (along with A and B), so that when the knob is turned, the all thread turns as well. L will have the mating internal thread and have a grove milled along its length to stop it spinning in I. Thus, turning A result in linear motion in L. How did I go?

I still would like to see some pics, especially to show the final relationship. Things like does the small diameter stub on B insert into D etc.