Tried a 3/8 end mill with a bigger stepover than usual on some 6061 aluminum

I was running some parts for a side job in my garage last night and decided to push a 3/4 inch stepover on a 3/8 inch 3-flute end mill just to see what would happen. Normally I'd keep it at like 30% of tool diameter but I went up to 75% on the finish pass. The machine growled a bit but the surface finish came out way better than I expected with no chatter marks. Has anyone else messed around with bumping up stepover on aluminum and got weirdly good results?

2 comments

2 Comments

the_elizabeth12d ago

Pushing limits works in machining just like it does in most things, right up until they don't.

paige_bell8112d ago

My buddy Mark tried this exact thing on his Tormach last month. He was running a 1/2 inch end mill with a 0.400 stepover and the finish came out mirror clean. He said it scared him at first because the machine was humming but the chips were coming off perfect. Then on the next part he got too greedy and went to 0.500 stepover and the tool snapped clean off halfway through. He ended up with a ruined part and a 60 dollar end mill in the chip tray.