Here’s a reminder to never leave your machine unattended or at least not out of hearing range. This happened to me while I was running a finishing toolpath with a short 1/8" ballnose that did not need to go all the way to stock bottom. Short stickout, I eyeballed it and thought “this is going to be close, but it should be fine”. I was wrong. I did not notice but my toolpath happened to go a bit deeper in some areas, and the spindle collet nut came crashing on a part. Rubbing a piece of metal spinning at 20.000RPM on wood did not end well. That burnt area is 0.5mm deep. I only saw it (and smelled it) after the spindle retracted when I hit the feedhold button
Yesterday I had a similar “should be fine” teachable moment… don’t assume that the set screws on carbide insert bits come tight from the factory… and (most importantly, I think) running insert bits without a protective barrier between you and the machine is just asking for a trip to the hospital with a piece of carbide buried in your gut. I know it would have given me a solid puncture wound if it hadn’t shot out towards the back left corner, gouging my waste board and the wall. This monkey is feeling rather stupid today…
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Aaaand I just developed a mild case of inserts-phobia now 
Glad it ended up with no injury, and I’ll see you later at the “I feel stupid today” bar.
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What is making me feel so stupid, and compelled to share, is the fact that the first time I saw an insert bit I said to myself, “Oh hell no, what idiot would run one of those outside of a fully enclosed machining center…”
Edit: to be fair, I know plenty of people use them with no incidents of failure… I have a smaller 90 degree amana insert bit that has never shown signs of loosening, heck I don’t know if I am going to be able to change out the insert when the time comes it seems so tight.
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Are you making a puzzle?
Yeah, just for fun to play along in challenge #12
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Remember the Sherpa Mantra - “Anyone can make a mistake, but Special people share them” !!!
Jon
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Hey @Microwave_Monkey have you got a link to that insert Mill please?
Jon
Rough day for me too. I had a new 30deg engraving bit, one of the really solid, .025" ones, drop from the collet after I thought I had hand tightened it enough. I let go to reach for the collet wrench, saw it go, somehow managed to, in a split second, consider my options and decided I did not want the new tip to get damaged. Like a ninja I went to catch it and it embedded about 5mm into my finger. The tip was saved but my wife thought I had cut off a finger with the amount of blood that followed. Didn’t think to get pics for this thread…barely a mark today. Those things are sharp!
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60 degree: https://www.toolstoday.com/v-14428-rc-1064.html (note: kinda odd after I sent them an email containing the exact pictures posted, it now shows a “pre-order” button instead of “add to cart” when I look at the product. More than likely purchased one of the last ones in stock…)
90 degree:https://www.toolstoday.com/v-10600-rc-45711.html (Currently really enjoying this bit, it cuts super clean even through masking)
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You can’t beat a gory pic of a minor accident 
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