Pro tip: I ran a job with a 1/4 inch end mill versus a 3/8 inch for roughing aluminum, and the difference was huge.

We had a big plate of 6061 to hog out at the shop. I tried the smaller tool first, thinking more flutes meant a better finish. It took over 45 minutes and the chatter was bad. Switched to the 3/8 inch, two flute end mill, same feeds and speeds, and it cleared the material in under 20 minutes with way less vibration. Is the bigger tool always better for roughing, or does it depend on the machine's rigidity?

2 comments

2 Comments

felix_fox5d ago

Well, there's your problem. You tried to use a toothpick to do a crowbar's job. Of course the little guy was screaming, it's trying to move a chip load meant for a tool twice its size. Bigger tool, bigger shank, less flex. My rule is to always use the biggest cutter that fits in the pocket, otherwise you're just making expensive confetti.

the_matthew5d ago

Forget tool size for a second. Look at the tool path itself. That little endmill is probably taking a full-width cut, burying its whole side in the wall. Try ramping in at an angle or using a trochoidal path. You're not letting the flutes clear the chip, so it just packs in there and snaps. It's like asking a guy to run a marathon while breathing through a straw.