I just snapped a brand new end mill and I can't figure out what I did wrong. I was doing a .1" DOC @ 14 IPM cut on my X3 with a 3 flute 1/4" HSS coated end mill from Enco. I plunged into the metal at a rate of .1" in 2" and it was sounding very smooth. After the plunge was complete it started a full width slot at 14 IPM. It still sounded very smooth and then just SNAP, broke right below the collet.

Anything above look suspect? I would like to have some "reason" before I load up another end mill. I'm about 3/4 of the way through a job and really don't want to screw the already completed work up.

-Jim