Hi all, I use a CNC T&CG, needed some help on ideas to grind a good end mill. always end up with some problem or the other....either the finish is bad or the life aint tat good or the tool sparks a lot...any clues.....

how deep does a end mill gash have to be and how wide9 usually do 3, 4 and 6 flute cutters)...is there a percentage related to the dia of the tool, or you guys just look at it and say tat looks good,,,,unforn for a novice like me everythin looks " good"!!!