Here is the answer I was looking for some time back. It has been great

revision for me and I have had considerable help from a mathematics forum.

The problem was to find the set-up angles required to make a skewed milling

cut in a rectangular block following given angles on three of its surfaces.

Image here:

formatting link

angles are A, B and C in planes YOZ, XOZ and XOY respectively.This is aright handed coordinate system with angles X -> Y, Y -> Z and Z ->X being +ve.1.

Align vice jaws // X.2. Set block in vice so that line at angle A is // to XOY3.

Tilt vice by angle D to XOY. WhereD = atan(cosAtanB)4. Rotate vice by angle E

from XOZ. WhereE = atan(cosAsinC/(cosCcosD-sinAsinCsinD))John.