I have a customer that's developed a new heavy duty shop vice they are wanting to market. They are using 1"-8 grade 8 all thread for the screw. What would be the best material for the "nut"? We had some 4140 annealed laying around and tried that, but it does seem to have some trouble goulding. We put a big load on it and it got tight and once we had it worked apart the screw threads are kind of chewed up.