I use a Magnate 2709 Surface Planing (Bottom Cleaning) Router Bit - 3" Cutting Diameter as a planing end mill. Big end mills like this should turn slowly. I use 8k RPM's and depending on the wood, can take up to 1/4", 6 ips. Harder, dryer woods I take less of a bite.
For a router, you probably won't have the torque to use such a large, heavy end mill. I suggest using one 2" or even 1-1/2" maximum with a router. Just be sure it's a bottom cleaning end mill which have cutters that go all the way to the center.
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