i use a carpenter's folding ruler that has the slide out on it, my vpi 10.5i came with a 6 inch rod and the arm is made with a grove in it for the rod to lay in, i sit the arm down on a lp and use the slide out to get the same fit on both sides of the rod, the area where the slide out meets the ruler is wide enough for this use, and it works very well. when i first setup my arm i used a 12 desk ruler, when i thought of this way of doing the azimuth adjustment i was off by almost a heavy sixteenth of a inch, when finished the ruler just touches both sides for the rod,
