Hello Future4200 !
I’m a new comer to F2400 this place is AMAZING ! … here goes a couple months of my life … down this rabbit-hole I go 
I should preface this by saying I have a very limited background in Chemistry, and overall a n00b.
So my question is : so theoretically speaking, for a solventless THCa isolation to be possible , Starting with a few grams of rosin, the THCa, Other Cannabinoids, Terps, Waxes, Lipids, Fats that are contained in rosin all have different melting temperature points (Correct me if I’m wrong), So would it possible to put rosin in a 20 or 25 Microns stainless steel mesh, heat it just enough for the wax to melt (say 25-30 degress Celcius)(Assuming waxes,Lipids,Fats, Terps melt at lower temp points than THCa) then apply enough pressure so that wax melted escapes the mesh into parchment paper, then repeat same procedure for Lipds , fats, terps etc… increasing the temperature by 10 degrees or so each time till all is left inside the 20 micron mesh is THCa crystals ? (assuming THCa/other cannabinoids have the highest melting point out of all the molecules present in rosin or BHO, which my limited research has led me to believe).
.
Where is my hypothesis going wrong ? Where is my logic chain falling apart ?.
.
Thank you 
