Well, the thing is, the magnet sits 1mm of the PCB. The problem is, I am super gluing a 1/4"1/16" nylon spacer to the PCB and then to the Magnet. The super glue is not working very well. It's not holding and they are coming apart. I need it to hold long enough to cast these things in resin.
My thought was if I got the smaller magnet, made the cut out in the circuit board for it with a 4mm diameter plated hole, solder that magnet in place (which would then be centered, no guess work trying to center both the nylon spacer and magnet), and then let the 8mm diameter magnet self center on top of the 4mm diameter one.
But, if it's not going to center as you say, I need to find another way of doing this. I tried hot melt glue, that isn't sticking to anything. I am using Gorilla Super Glue.
I know I can have magnets made that are called TopHats. They appear to have smaller diameter magnet under a larger one, but That will be expensive.