my crane rockers are 9/16 size socket lock nut and a allen adjuster
i make mine a tad tight and on mine it gets looser when the lock nut binds the threads.
i cut a deep socket and welded it to a piece of flat stock steel
drilled a hole for a "t"handle allen and easy as pie. it was a eye opener finding out i needed to go 5thou tight when doing it cold though.