Need help with long endmill/chatter
Currently running a CNC mill working on a big block of A36. I need to put a 1.772" wide slot from one end to the other (so technically more of a channel) and it needs to be 3.15" deep. I'm using a 1" 4 flute general purpose carbide endmill with 4" LOC. I started at 225 SFM and 0.15" DOC at 0.002" CPT, and was getting some pretty rough chatter. I tried dropping the speed to 200 SFM, and edging up the feed, but really the only thing that has helped with the chatter at all has been changing the depth from 0.15 to 0.1 and then to 0.05. It's better but it's still squeaking the whole way through. Does anyone have any advice on how to get this running more smoothly so the chatter doesn't chip all my cutting edges? Am I way off base with my speeds/feeds?