So before I got my Chinese re-501 a couple years back I was using a short path distillation unit to distill the alcohol.
What would happen is the obvious the alcohol fractionated three separate ways into three seperate flasks and had 3 separate odors.
Jw, Does this mean that there’s a possibility that fractionation of the terpenes in the alcohol was happening?
I believe the short answer is yes, to some extent, but without knowing more about how exactly you were catching your recovered alcohol (I’m guessing triple cow?), what temperature you were distilling at, and specifically what each fraction smelled like, it’s hard to really tell you too much more.
While I am certainly no expert in terpene fractioning, I can say that terpenes come in many shapes and sizes. Boiling points can vary wildly, and there is likely some separation you were experiencing. Those separations, however, are likely super muddled and not clean cuts or usable for anything special.
The easiest way I can explain this is by reexamining the (cannabinoid) distillation process. Crude before devolatilization often carries the nose of the flower to some extent. Those good smelling terps are almost exclusively monoterpnes, which are light and have a very low boiling point. These are the first to go.
Heads fraction would be your next set of terps. As you have I’m sure experienced the smell of heads is something less than desirable, and it has a very distinct, sour smell. With no more volitile (good smelling) monoterpnes, all that can be smelled are the heavier terps (mostly sesqi-terpenes and tri-terpenes).
Tails fraction also has a different nose from the feedstock, heads, and hearts which presents itself as another special kind of awful (as only some of those heavier terps have been removed). While heads and tails both smell awful, no matter the feedstock, they do smell distinctly different. If you’ve ever experienced this, which every processor making distillate has, then you have experienced the fractioning of terps (along with other goodies).
I’m fairly certain you were doing the same as described above with your distillation of alcohol, but to what extent and with what purpose it could serve you, I have no idea. Hope this helps answer your question a bit. If you wanted to clean up your terpshine and return to just having alcohol, there’s tricks for that too. AC has been used in cleaning up alcohol distillation for a really long time.
I’ve actually never made disty cause I don’t have a pump that can pull the crude or a cold trap for in between the pump and the system. I don’t have a backing pump or a diffusion pump either.
Yes it was triple cow.
I just wanted to know what was going on. Thank you for the detailed response.
How do you fraction off ethanol? Clean, out of the jug, nondenatured (azotrope is too close to seperate).
There are heads hearts and tails even when distilling alcohol. If I remember correctly, fractioning appropriately can work as a process for deodorizing terpshine, though I have not had success with that particular trick, nor have I spent any real time trying to do so.
You are correct in that the azeotrope with ethanol and water is really hard to break, especially if using denatured alcohols. That being said, reproofing (upping the proof) of ethanol is very doable up to 190 proof through simple distillation and the discarding of tails (where there will be higher water content). Again though, not a trick I have performed, as my ethanol never dropped low enough to require reproofing.
I would assume that the OP collected fractions in each of the three receiving flasks, filling them until they were full then rotating to the next. Might not be accurately measured fractions, but they are fractions nonetheless.
Yes that’s exactly what I did. Mind you this was some 3 - 4 years back when I was using a BVV cold trap and a 7cfm two stage rotary vane hvac pump, regulating the vacuum by the cold trap handles. 
I think I wasn’t even distilling at the right temps either, man I was wreckless, my how this forum upped my safety game.
I’ve only been here for a 2-3 years but still like ived learned a lot.