Lost a full shift to a dull 3/8 end mill, check your feeds first

Last Tuesday I roughed out a part in 6061 and blamed the machine for an hour before I checked the tool. The end mill was 3 weeks old and I kept pushing the same chip load from the day I installed it. Burned through 8 hours and a $45 replacement because I was too stubborn to drop the feed rate. It cut fine on the first few parts, so I figured the tool was still good. Cost me the whole afternoon and a rush delivery fee on top of the new bit. Anyone else get humbled by a worn cutter that seemed fine on the surface?

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ray3631mo ago

Did you check the runout on that holder before you blamed the feed? My buddy had the exact same thing happen last month, swore up and down his speeds were right. Turned out the collet was off by a few thousandths and the tool was chattering harder as it wore down. He ended up scrapping a whole batch of brackets before he found it. Sometimes it's not the feed at all, it's the whole setup going soft on you.

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