On Feb 27, 7:23*pm, "Robert Swinney" wrote:
Not sure I understand how removing threads can keep a bolt in place.
Bob Swinney

You tap both the cover and the box. Then you turn down the shank under
the head so it turns freely in the tapped hole in the cover. It works
as long as the screw threads don't start into the cover threads before
they disengage from the box, meaning there has to be clearance between
the cover and the box of at least the length of engagement in the box
threads.

Jim Wilkins