I’ve been running into an issue with the Avid ER32 collets and nuts getting damaged during normal use. It looks like galling/scraping at the interface and I’ve been trying to track down the cause.
For torquing, I’ve been using a Martin Precision Tools ER32 torque wrench adapter and applying their conversion factor to reach the 100 ft-lb that they recommend on their website. I use the avid iso30 tool tightening fixture when installing bits and I am careful to remove any dust/debris. I haven’t had too many tool changes either - maybe 5 max per tool holder and I am seeing the same issue occur on most of the tool holders I use. I don’t believe the bits are slipping nor do I think the collet/nut is rubbing during cutting. I think if they were slipping during cuts I would be seeing more of a smooth scrape vs the bumpy one that’s occurring here.
My current theory is that the collet may be slightly rotating or twisting inside the nut during tightening, exposing sharp edges at the interface and scraping material off the nut. Once that begins, it seems to snowball. Burrs build up, the contact becomes more uneven, and the collet no longer loads uniformly and flexes visibly unevenly when torqued because some of the slots in the collet appear to catch burrs on the nut.
I have found a couple threads where others appear to be seeing very similar damage:
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https://www.practicalmachinist.com/forum/threads/why-are-we-damaging-our-er32-collets.304667/
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https://www.reddit.com/r/Machinists/comments/puvhtc/holy_spinning_collets_batman_what_would_cause_a/
They appear to attribute it to either out of spec collets/nuts or play in the spindle. I checked my spindle taper with dial indicator and the runout looks perfect.
I’ve already ordered new collets and nuts, but wanted to see if anyone else is having similar issues so I can avoid having to replace them again in the future.