Slicing at an angle

 From:  Frenchy Pilou (PILOU)
7775.5 
Just increase the size of your "face plane" and all will be working fine! ;)

Use Transform / Scale 1D
or The Edit Frame ( Clic an "angle corner" for Toggle "Center / Extrimities" symmetry ) visible following! :)

EDITED: 13 Dec 2015 by PILOU