After reading this thread I got to looking at my bed it has sunk down in between my crossmembers. I think i know why. I used 11ga smooth metal for the top and welded it to 2"x2"x11ga square tube. on 2ft centers guess i should have gone with one ft centers. this is my 3rd bed. never have had this trouble but all the others i used 11ga diamond thread which is a lot stronger. Am I thinking right?