With the advent of loop-to-loop connections from fly to leader, many fly fishers have gotten away from the tried-and-true nail knot. I’ve tried both (and other options), and among them all I find the nail knot to be the strongest connection with the least likelihood to “hinge”. My long-time tool to make tying the nail knot easier was an inexpensive small U-shaped channel that was attached to a nipper. It was great for years in fresh water, but only a year in the salt had the pivoting joint bound up tight in spite of being cleaned and lubed after every trip. I went online to dig up a replacement, and found the Duncan “Tailknott’r”.