Further to yesterday's work, I had a couple of studs that needed to be removed. One stud needed the nut on one side to be backed off to better centre the stud and provide sufficient threads for the opposite side. This nut wasn't moving since the stud and nut had been tapped with a punch to prevent from backing out. In fact, this was the technique that Dalotel did for all these studs. Notice that the centre of each stud has been drilled out slightly. I suspect this was done to provide some movement when the threads were tapped. It was an effective approach because this nut would not unthread. While trying to unscrew it, I overtorqued the stud which broke off cleanly below the surface. It was going to have to be replaced anyway since the stud wasn't fitting properly. A little tap or two with a punch and the stud was removed. I had a couple of nuts that needed to have the threads re-cut. The threads of the stud had galled onto the nuts. Galling is the process of similar metals or metals with similar hardness rubbing against one another and essentially fusing to each other. Since this was aluminum on aluminum and aluminum is quite soft, the risk of galling was quite high. Once the two surfaces have galled, you are NOT going to get them apart. A specialist in metals and materials could explain the difference, but for the layman such as myself, I equate it to friction welding without the heat.