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Vent: 6 hours chasing chatter on a 4140 shaft because I skipped one setup step
Had a 4140 shaft job on the lathe a couple weeks back, 3 inch diameter, 18 inches long, and it started singing about 40 minutes in. I figured it was just tool wear so I bumped the speed down and kept going, but the finish got worse and the size started drifting about 0.004 over the length. Turns out my tailstock center wasn't seated right and I never checked it because the part looked fine on the first pass. Wasted 6 hours and $180 of material before the old timer next bay over asked me one question about my setup. Now I check the center before every long shaft, takes 30 seconds. What's the dumbest setup mistake you've made that cost you half a day?
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lunah1222d ago
Did you check the center before or after you dialed in the part? Ran into almost the same thing on a 17 inch piece of 1045, tailstock was off about 0.002 and it walked my size the whole way down. What fixed it for me was marking the center with a sharpie and spinning the quill by hand first, if the mark wobbles you know it's not seated. Also started putting a little spot of way oil on the center tip, cuts down the squeal a lot. The old timer in my shop told me the same thing, check the center before you touch the speed dial. Now it's the first thing I do before I hit start on anything long. Feels dumb in hindsight but it sure saves a whole day.
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