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Rant: The old guys at my shop convinced me I was wrong about cutter speeds
I had a talk with Al, our lead guy who's been running mills since the 80s, after I got a part rejected last Thursday. He told me I was pushing my spindle way too fast for that 4140 steel, and I argued back about modern tool coatings and chip load. He just pulled out a worn end mill and said, 'That's your problem, you're burning them before they cut.' It hit different because he showed me three parts he ran off at half my RPM that were dead flat and mirror finish. Anyone else had an old timer prove you wrong with just a part in their hand?
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reeseperez5d ago
Man, I remember reading something from a retired tooling engineer who said the same thing about aluminum years ago - everyone thinks faster is better until someone shows you the actual finish. It's wild how those old guys can just eyeball a speed and feed and get it right, while we're over here crunching numbers on apps. Makes you wonder how much we're overthinking this whole modern coating thing when the basics still work.
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veraj534d ago
Did Al show you the actual cutting data from those parts or was it more of a "trust me, I've been doing this since before you were born" kind of thing? Because I'm curious if he had any specifics on speeds and feeds or if it was just raw experience telling him to slow it down. The mirror finish part is interesting too, because that usually means something about the surface speed and chip thinning, not just raw RPM. I wonder if he was running a different stepover or DOC that made the finish look that good.
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