Appreciation post: The old timer who told me my feeds and speeds were garbage

About 3 years ago at a shop in Cleveland, a retired machinist named Frank saw me struggling with a stainless steel part. He walked over and said, 'You're running that thing like it's aluminum, kid.' He showed me his worn-out notebook with hand-written rakes and angles for every material. It completely changed how I approach cutting, and I still think about that conversation. But everyone else in the shop swore by their CAM software defaults. Has anyone else had a veteran teach you something that contradicted the manual?

3 comments

3 Comments

diana6179d ago

Ever notice how those CAM defaults seem like they were written by someone whose only shop experience was in a cubicle? @wood.eric hit it about the heat management thing. Frank's notebook had notes like 'this angle works unless it's Tuesday' but man, it was always right. I once spent 45 minutes fighting a part until I remembered his rule about chip thinning and cut my feed rate by 40 percent. Tool stopped screaming and I felt like an idiot but a smarter one.

wadew519d ago

Actually that 40 percent cut makes total sense but I think you might have been fighting more than just chip thinning. Frank's rule about chip thinning usually only kicks in below a certain radial engagement like under half the tool diameter. If you were taking a full slot cut then chip thinning isn't really your problem it's more about the chip load piling up and not evacuating. That 45 minute struggle probably had some built up edge or deflection going on too. I had a similar thing with a 3/8 endmill in 304 stainless where dropping feed helped but really I needed to bump up my stepover to let those chips breathe. Just something to chew on next time you're cussing at a part.

wood.eric9d ago

Did that notebook have sketches of tool geometry too? I had a similar moment with an old gear cutter who showed me why his speeds were half what the book said for certain alloys. He had this whole theory about chip thinning and heat management that the software just ignored. The real gold was watching him adjust on the fly, like he could hear when the cut was wrong before the tool even touched the part. I still cycle back to his basic principles when I'm fighting with a tough material.