Blend Issue: trying to blend the connection between two objects

 From:  Frenchy Pilou (PILOU) 25 Jan 2019  (2 of 7) 
9229.2 In reply to 9229.1 
Select big surface cylinder : Edit / Join

Select little surface cylinder : Edit / Join

Select 2 open circumferences : Construct/ Blend

et voilà :)