David Ford wrote:
I need to find a router bit the will cut a "groove" with a 2.5 to 3
inch diameter. I only need the groove to be about 1/4" deep.

snip

You have two (2) choices.

My choice would be a lathe; however, if you must use a router, find and
old Craftsman Router/Crafter like the one I still have someplace.

HTH

Lew