Anneal the end of an arbor while leaving the morse taper unaltered.
I just stumbled across this. I wanted to machine the ends of 3morse arbors but did not want to wait for or find soft end arbors. I wanted to anneal the ends while keeping the morse taper hardened.
I cut up an old carby cleaner can to make a cup of water to sit the whole of the taper in water. To keep the arbor centered, I just removed the collar where the tube comes up through the can with side cutters and pushed it through. If you flip it upside down it is a perfect fit for 3morse tapers.
Fill it with water to just above the taper and heat the post with a map gas torch. It only took a min or two. Once it's nice and red let it slowly cool in the can of now warm water.
It worked a treat. Easily machined with m42 HSS and sutton drills.