G'day.
I still have a demagnetiser from early computer days. It works on steel cutting tools too.
My tools usually get magnetised due to sitting a magnet near the toolpost when working with cast iron. Lol, probably a bad habit I suppose 
Some time ago I did a bulk buy of rare earth magnets for use in the workshop and thought of lots of uses for them. Although I still find them useful for some things, I now use them only temporarily on machines. The problem is they magnetise tools and things you don't want to be magnetic and collect swarf which is difficult to get rid of.
Cu later * Danny M *