I have only had opportunity to check a very few of the Lefever Ball Screws. The ones I did check however were straight, checked with a micrometer on both the OD & over thread wires for the pitch dia of the thread. What I did find was that the tap was stopped short (Quite Precisely) of going through the frame so that as the ball came into adjustment the threads were tightening up in the lead of the tapped hole. This effectively secures them from accidental movement, while still allowing "Enough" adjustment to take care of wear.
