端銑刀組，6 件 4 刃，鈷合金

These 4-flute cobalt mills bite through steel cleanly without chatter, and the set covers the sizes I reach for most. Even the 3/8 inch ones hold an edge longer than my old HSS bits, so I’m not swapping them out mid-job.

Spent the afternoon cutting 6061 aluminum on my benchtop mill and the 3/8 inch flutes held up beautifully without any chatter. The cobalt construction feels noticeably sturdier than the HSS set I replaced, and the 4-flute geometry left a cleaner finish on the shoulders than I expected. For the price

Just machined some aluminum brackets with the 4 flute cobalt set and the 3/8 inch bit held its edge surprisingly well through the whole job. The included sizes cover all my common needs without having to buy individual bits.