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My foreman in Milwaukee told me to run the boring bar at 800 rpm and it wrecked the part
I was new on a big lathe job, making a 6 inch bore in a steel housing. The old foreman, guy named Ray, swore by high speed for a clean finish. He said 'just crank it to 800, it'll sing.' I did, and halfway through the final pass, the insert chattered so bad it looked like a washboard. The part was scrap, a $500 piece of material gone. I learned later that for that specific bar length and material, 350 rpm was the sweet spot. Ray was great on mills but his lathe knowledge was stuck in the 90s. It taught me to always double check speeds with the tooling rep's charts, even if a veteran says otherwise. Anyone else have a 'trusted' tip that blew up in their face?
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phoenix_wells6mo ago
Remember the tooling itself can be the wild card. I had a boss push for high feed rates on a brand new endmill, saying the coating could handle it. He didn't know the shop guy had been resharpening the old ones on a bench grinder... the geometry was totally off. So the 'good' advice was based on a tool that didn't exist anymore. Sometimes the old rules fail because the tools on the floor aren't the ones in the catalog.
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mason7286mo ago
Come on, was it really that bad? So you scrapped one part. That's just the cost of learning sometimes. Like anna983 said, maybe the old guy's advice works fine on a different setup. I've seen guys run stuff way outside the book specs and it turns out perfect. Isn't the real problem that nobody told you it was your first time on that machine?
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