I'm unclear on if you actually cut fresh threads on the junk fork. If you did how does the Schwinn cone fit over the new threads? Part of what controls the fit of threads is how much material the die has to remove and the material alloy, so the cone should fit more snug on the fresh threads has they have had the most metal removed. also the Schwinn tube is .007" bigger dia. so the cone should fit tighter on the larger tube. It would be best to get an adjustable die and open it up so it cuts as little as possible and test the fit. To help the die start, run the Schwinn cone a ways down the Schwinn fork, then grind a chamfer on the end of the steerer tube. When you remove the cone it will chase the threads then the die should start. Opening up the die will also let it start easier. As the text under the last illustration says you can always adjust the die by closing it up and cutting more metal away to make the cone fit looser but you can't add it back.