Magnets on my stir plate

Hey everyone!
I recently decided to build a stir plate, more for the fun of constructing something than for actually needing one (I usally pitch dry packets, Im definatly going to use this bad boy though). Everything is completed on it except for the attachment of the magnets to the fan. I scored 2 neodymium crecent shaped mags out of an old hard drive, and they are pretty similar to the other mags I've seen on here that people have sourced from HDs. I was wondering if anyone could clarify the correct position to attach these magnets.
Should I set them up in the circular pattern where the 2 magnets are in opposition, or should I stack them one on top of the other and then center the stack on the fan? how do you guys have it rigged? whats the difference? I plan on using some epoxy to nail them down. thanks a lot everyone!

Across from each other and one should be turned upside down.

When I glued mine to the fan they kept sliding toward each other. Talk about a comedy of errors...fighting magnetism...

I found a round cap from some small bottle and used it as a seperator.

I only used one in my project and I found the magnetic center and put that point in the center of ratation on the fan motor.... See photo below.....

NOTE: I cut the hole in the hard drive enclosure because aluminum is non permeable material and will not let the magnetic lines pass thru it without deminishing the magnetic force....

DRAGGER.....