I suspect no one out there is understanding the question I'm trying to ask. The atop nut threads onto the draw bar and is locked into position on the draw bar by tightening two setscrews (#9) with two brass shoes (#8) which are located between end of said setscrew and external threads on the lever end of the draw bar. Said shoes purpose is to keep set screws from damaging external threads on draw bar. Once lock nut is secured to the drawbar, the user can then install and adjust collets for workholding. If I thread said stop nut onto the drawbar to the limit of thread engagement and tighten setscrews, the lever will not 'break over center' and therefore will not remain in locked position with lathe running. When I back off stop nut from 100% thread engagemnet with drawbar (in other words, loosen it) so that a 1" workpiece is properly held in a hardinge collet AND the lever DOES break over center all is well. However, when I replace the 1" collet with a 3/16" Hardinge collet and attempt to hold a 3/16" end millwith proper collet engagement, (by turning the stop nut which was locked to the drawbar via two setscrew) as has been previously described by others, the leverwill no longer break over center. Therefore, was it intended by SB for the user to adjust stop nut TO drawber thread engagement until any and all collets successfully allowed lever to break overcenter? Does the fact that the stop nut is only partially threaded onto the drawbar have any negative effects?
A very longwinded explanation of my original question...