Mike, I didn't look at your linky, but I'll save you from buying it!
Get a section of styrene TUBE with the ID the same as the OD of the rod you want to drill...
Mark the end of the rod you want to drill with a sharpie to make it easier to see your mark.
Place the section of tube over the rod.
Using a drill bit the same size as the rod, twist the bit inside the tube, contacting the end of the rod you marked.
Remove bit & section of tube, and you'll be left with the center perfectly marked, as well as a dimple to act as a pilot for your desired finished hole size.