Collet nut cracked mid-run on that big aerospace job today

Was feeding through a 3/8 end mill at 12K RPM and heard this nasty ping... looked down and the nut had a hairline fracture from who knows when. Had to scrap two parts before I caught it. Anybody else check their collets before pushing start?

2 comments

2 Comments

cole_mitchell81mo ago

Read a post on another forum where a guy said he always taps his collet nut with a wrench before loading a tool, just to hear if the sound changes. Supposedly a cracked one rings different than a solid one, kind of like a cracked bell. Been doing that myself after a similar issue, seems to catch the bad ones before they cause trouble.

stella_lee1mo ago

That "rings different than a solid one" thing is exactly how I got into doing the same thing... but man, I have a story about that. First time I tried it, I tapped the nut and it sounded totally normal, so I loaded up a big endmill. Then later I realized I had accidentally tapped the wrench itself, not the collet nut. Real genius moment there, @cole_mitchell8. So now I make a point of actually touching the wrench to the nut before I tap it, otherwise I'm just a guy hitting air like an idiot. It does work though, once you get the hang of telling the difference between a dull thud and a clean ring.