Wrong spindle speed advice cost me a full shift and a $400 part

Back in 2012 at a shop outside Cleveland, a 30 year machinist named Ray told me to stop swapping cutters so often. He said a slightly worn end mill gives a better finish on aluminum because it burnishes instead of chattering. I thought he was crazy, so I kept changing tools every 200 parts like the manual said. Then one Friday I forgot to order new 1/4 inch bits and had to run 600 parts with the same dull one. The surface finish came out smoother and the cycle time dropped by 18 seconds. Anyone else ever get advice that went against everything you learned in school?

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schmidt.willow11d ago

Ray was right about burnishing, but that same trick ruined my bore gauge on a Tuesday nobody warned me about.