However, in my case, I knocked a case of drill bits off the bench accidentally. Then I gathered them up with a magnet. So that’s two mistakes. The only way to get all the swarf off,was to polish them with a rotary fibre brush. At least they’re clean now, and ready for use, if not strictly in order, but they’re still magnetic. But I have frequently noticed drills retaining the swarf, so you’re probably right about the alignment. Thank you.