端銑刀，4刃，M42鈷鋼，單一尺寸

The M42 cobalt really holds up—I’ve been running these at a high feed rate on some tough steel and the cut quality hasn’t faded. The 4 flute design leaves a much smoother finish than my old 2 flute bits.

I was a bit skeptical about the 4 flute design, but the high feed rate is real and left a much smoother finish than my old 2 flute bits. The M42 cobalt gets noticeably less hot during long runs too.

The center cut on these made plunging into mild steel a breeze, and the M42 cobalt held its edge through a full roughing pass without any chatter. I was genuinely surprised how clean the finish came out on the side walls, so I’ll be stocking up on more sizes.