Let me begin by describing the part. It's basically a box with an angled lid from front to back. On the inside of the front face there's some reliefs about .125"ish deep with .125 corners. The only way I've seen to reach this is by setting the box on the front face and coming in from the back. The clearance there is 4.6" or so. (I misspoke in my first post, it's deeper than I remembered)
So the actual feature I need to do is a profile cut with some .125 corners at a .125 depth 4.6" down inside. Corner drilling won't help me as much because the point on the drill will go to deep and not give me enough clearance in the corners, there's only about .08 wall thickness to the outside face. What I came up with this morning is using a 4 flute on my finish pass at 385sfm and .015 chip load, .01 DOC and only finishing in the corners using trochoidal pocketing. I'm using a larger endmill for the main passes. It gives me a decent finish, not the best but acceptable. I may play with some other options that were suggested to try out something a little faster. I tried all different feeds and speeds this morning and a few different DOC and WOC. 2 flutes were giving me a pretty rough finish no matter what speed I ran it at. The 4 flute seemed to do decent enough. I should be ok with the 4 flute cause it's just a finish pass and shouldn't have to worry about chips clogging it up. I'll just have to get a green wheel and relieve the shank a little cause it was just a regular extra long length one that was laying around.
There's only 3 of these I have to make so no large production runs. I only work on prototypes so I'm always doing these one off things.