PSA: I was convinced a 3-flute end mill was just for aluminum, but it cut 304 stainless way better than my usual 4-flute.

Ran a test piece after a machinist in Cincinnati swore by it, and my surface finish improved by about 15%. Anyone have a go-to tool for stainless they thought wouldn't work?

4 comments

4 Comments

michael6693mo ago

Read somewhere that fewer flutes can help with chip clearance in gummy stuff. Makes sense if it was loading up before.

mia7003mo ago

Yeah, that tracks completely. I was fighting some nasty 6061 the other day and switching to a two-flute made a world of difference. The chips just couldn't get out of the way fast enough with more flutes, everything just packed in there. It's one of those things you don't really think about until you see the mess it makes.

taylorshah3mo ago

Wait, you found a machinist in Cincinnati who actually gave out real advice instead of just grumbling about coolant? That might be the real miracle here. I'm stuck with the old guys who treat tooling choices like state secrets. The three flute thing makes total sense for chip clearance, but I'm just shocked you got a straight answer from someone.

nancyn691mo ago

lol yeah the secret keeping is real. i lucked out cause the guy was in his 70s and just wanted someone to talk shop with. but your mileage may vary, some of those old timers will die before they tell you their speeds and feeds. i found that bringing them a specific problem (like "my 6061 keeps loading up on this finish pass") gets better results than asking general stuff. they love solving a puzzle more than handing out trade secrets.