Old timer at the shop changed my feeds and speeds entirely

There's this guy Gary who's been running CNCs since the 80s at our shop in Toledo. He watched me struggling with chatter on a 304 stainless part and just said 'slow your spindle down to 1800 and bump the feed up to .008 per tooth.' I thought he was nuts at first, but the finish came out glass smooth after I tried it. Has anyone else had a machinist vet totally flip your approach to speeds and feeds?

2 comments

2 Comments

alice8081d ago

Gary's probably got decades of hearing how inserts actually cut rather than going off what the book says. Sometimes those old timers know which speeds let the chip thin out right instead of fighting vibration.

noah4151d ago

Running 316L with a 1/32 radius insert, I was getting chatter bad on a finish pass at the book speed of 450 SFM. Dropped it to 280 and bumped up the feed just a hair, and it smoothed right out. Chip breaker finally engaged and I got a mirror finish instead of that wavy garbage. Took me three scrapped parts to listen to the machine instead of the manual. You ever just ignore the recommended speeds and find a sweet spot by ear?