To attach the exhaust pipes to the cylinder head, Norton used a finned flange nut that screwed into the cylinder head on the 750/850 Commando models. They looked great, but there were a couple of problems with this. First problem was that the threaded steel exhaust flanges had a tendency to become stuck in the aluminum heads. Removing them often involved a lot of torque and a lot of cursing. Second problem was finding something that would give a solid grip on the finned surface of the flanges that would let you apply the huge amount of torque needed to the loosen the flanges without bending, breaking, or cutting the fins. These parts typically go for more than $100 a pair, so hacking them up with a pipe wrench is not the preferred approach. Back in the Paleolithic Era, when I was turning wrenches for a living, I made this wrench to get the exhaust head pipes on/off the Commandos. It is 23 inches long and made out of 3/8" aluminum plate. 6061 was used to give the tool some added strength. To get the teeth right, I traced a pattern of the flange nut onto a small piece of poster board, then transferred it to the plate. A bandsaw was used to cut the plate. Final finish was done by filing by hand. This thing works pretty well, but there is still a lot of swearing and often the use of a rubber mallet in conjunction with the wrench.