Hello, I have a different use for the dowel jigs, whether it is a Stanley, or one of the self-centering jigs. I have had to drill a hole from the hinge side of a solid wood door, to the latch side, for an electronic latching system. The widest door we drilled was 48 inches!!!! I draw a level line across the door ( on blue tape) and then connect with a square line on each edge. I set the dowel jig for center, ( we usually use a 3/8 dia. bit), and use the drilling guide for my 1st hole with a jobbers length bit. Then I drill agin using a 6" length, 12" length, 18" length, and then a 24" . Repeat the process from the other edge and (hopefully ) meet in the middle. The jig keeps the holes straight, and once you get past the 12" bit, the hole is your guide.We had to weld an extension on the 24" dit to get to the middle of the 48" door. Regards, Lou