Had a complete toolholder failure on a Haas VF-2SS yesterday

I was running a finish pass on a 17-4 PH stainless part at 8000 RPM when I heard this godawful bang. Pulled the cycle stop and found my ER32 collet nut had literally cracked in half, sending the endmill flying across the enclosure. The part was already scrap since it dug a 0.050 inch groove across the finished face. Took me 2 hours to dig the broken collet pieces out of the spindle nose with a pick set. Has anyone else had a collet nut just give up like that with normal torque?

2 comments

Log in to join the discussion

Log In

2 Comments

oliver7193mo ago

Damn, that's brutal. I've seen collet nuts wear out over time but never had one actually split in half like that. Hope you got that spindle cleaned out good, those little shards can mess up a bearing race quick.

4

paule533mo ago

Had a similar thing happen on a BT40 holder a couple years back. Switched to using a torque wrench set to the manufacturer spec and never had another failure. Those collet nuts can get hairline cracks from overtightening.

3