The main problem is in the last sentence of your specs. ''I have to do this dry'' Some WD40 in a spray can will make a world of difference, I also use soy oil (cooking oil), apply with a brush or an oil can. If you look at the broken pieces of cutter you will see that there is aluminum welded to the cutting edges, this is due to the lack of lubrication/coolant. 6063 is gooey stuff to machine.
3000 RPM seems a bit light for a 1/8 end mill. You should be using a 2 flute end mill, this will give more chip clearance than a 4 flute. You might try to do the cuts in 2 passes, 0.063 depth of cut.