With your vinegar bath complete and the rust apparently gone, dry the pieces off. Now take one of the pieced and rub it with a crumpled up piece of aluminum foil. Before rubbing, run your hand or fingers over the piece and feel how rough it is. After rubbing, feel again. You will be amazed how much smoother the piece feels.

Now,wax the piece with a decent wax. I use Mothers Cleaning Wax and it works great.

That should take care of the rapid rust return and you will have removed even more of the rust with the rubbing action.

Hope this is a help.