I'm trying to make the profile cut on these parts with a 1/8" endmill. As you can see from the pictures I'm getting some chatter. I've tried both a 2 flute and 3 flute carbide endmill. The endmill sticks out of the ER32 holder only about 3/4" of an inch. The total depth of the profile is .26". The bottom two parts I used a .055" step down level to get to my .26" total depth and left .012" for a finish pass. As you can see the finish pass has a bunch of chatter. I then tried simply leaving no material for a finish pass but still using the .055" step down (the top part in the picture).
I'm running the speed at 10,000 RPM, 13ipm feed rate (.000625 per tooth). It's 6061 aluminum.
Any ideas?