I would like more feedback on 3 vs 4 flute end mills. Someone suggested that a 4 flute will actually "recut" a chip that gets caught on the side opposite the cut , causing the tool to deflect . I am using 4 fl Garr tialn that cost about $9.00 each . Running a 1/4 mill at 4500rpm /8 IPM in and a 20ipm springpass out to mill 1/4" keyways . I can do a 3" keyway in about 44 seconds , but am getting a bit sloppy on the width . I have been using 4 flutes for so long, that I forgot why I never tried 3 flutes . BTW these GARR mills are the best value per inch of keyway that we have ever tried . Increased my bottom line by going to a cheaper mill ! Was using HS Tin before I got smarter!