In a previous unrelated post another member commented on the technical difficulty of achieving the adjustment mechanism. As I have been working on the same project and also had difficulty understanding the instructions, perhaps some more experienced members could explain the cuts necessary.

Perhaps where I am going wrong is I don't fully understand engineering drawings.. One of the many topics I need to get a hold on.

Anyway back to the topic from my understanding from the drawing on page 19 'Lathework a complete coarse' it seems that a vertical slot of 2mm is cut into the base. This doesn't make any sense to me as I cannot see why the base would need to flex in this area. Also he mentions the v grove around the circumference disguising a cut or cuts. I am left unclear as to where the cut or cuts should be placed. For instance should it be where the clamping screw goes or adding a 2nd parallel cut on the offside to create a hinge effect or could you use a parting off tool to remove a few mms all round?

Pics of project so far including failed attempt at milled 'nurling'. I tried to get a bit amitious instead of hand filing I set up a rotory table I had not used before on the milling machine. The work wasnt sufficiently clamped and the cutter wondered, oh well back to the mark 2 attempt.

Thanks Michael & Bert, if the book had said to cut either side to make a hinge this would have made more sense to a complete novice like myself. I initially thought that the hatched area was an additional vertical cut.

Your explanation makes more sense. In my defence a complete newbie has to cover many topics when starting out, some of which come up from technical problems with kit and materials and some form lack of clear explanation to greenhorns like me.