That's often addressed by grinding a slot, using a slitting blade. You should do some grinding in that area, anyway, as once the end geometry is removed, the center no longer has the ability to cut. You have to use good judgment, as you can't touch the tip of the end mill, otherwise it creates a slight taper in the periphery, where the slot that is created removes a trace of the flute. When you do go beyond the tip, the primary relief grind of the flute is removed, which is why the angle is created.whateg0 wrote:There are plenty of videos showing sharpening of the ends of endmills. I used an old Craftsman 6" lathe for this with HSS endmills. Indicate the endmill in in the 4-jaw then set the compound at 2 degrees. Then pass a dremel over the ends. I need to learn more about the geometry, though. On some of them, there was a small section hanging down below the corners of the flutes, even with a 2 degree angle.
You can also kill that small area, using the corner of a sharp wheel. Hit the raised area enough to remove it, then index the end mill 90° and repeat. So long as the center is removed, the end mill will cut properly. End mills so ground do not lend themselves to plunge cutting, although they will ramp quite well.
H