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Old timer on my shift said never trust the first part off a bar, and he was dead on
Back when I ran a Hardinge lathe in Rockford, a guy named Dale with 30 years in told me the first piece off every new bar runs a few thousandths off because the stock relaxes once you cut the skin. I blew him off for weeks until a batch of 200 bushings came back .004 undersize on every first part, and the scrap bin told the story. So who's with Dale on this, do you guys scrap the first piece off a new bar or measure it and run it anyway?
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ivancoleman14d ago
Funny how the guy with 30 years and grease under his nails is always right and the guy with the shiny new setup sheet is always wrong. Dale basically handed you the answer for free and you still had to feed 200 bushings to the scrap bin before you believed him. That first piece off a fresh bar is like the first pancake, nobody wants it but you gotta make it anyway just to see what the pan's doing. The skin was holding that stock under tension the whole time, so the second you peel it off the thing relaxes and moves on you, that's just physics being rude. Measure it, log it, and if it's out past half your print tolerance then yeah, that one's a practice part. Cheap lesson at four thou, wait until it's a five hundred dollar forging and see how fast you learn to listen to the old guy.
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