Ok... I'm still mulling over the possibility of a Hilsch tube on one of my
machines as the coolant and to blow chips away from the cutter. I see many
commercial ones are made out of stainless, but that just isn't in my plans
if I make one. Stainless is beyond my easy working level.

I have some large aluminum bar stock laying around, (left over from another
project) and I was thinking I could turn one out of it. My quandry is in
this. I only ran across a few mentions of heat sinking in regards to Hilsch
tubes. One article said to heat sink the whole thing. I think they just
meant the whole heat separator/exchangers side of it. It would be counter
intuitive to heat sink the cold air outlet tube. I would think you would
want to insulate that. The thing is the physics of it is beyond me. I get
the basics of both principle said to be at work. It's the details.

I could easily turn heat sink fins on the outside. I just wonder if that
will provide a lower ouput temperature, or if somehow it might reduce the
efficiency of the design somehow?