Abstract: A whipstock assembly includes a whipstock and a non-retrievable setting tool. The non-retrievable setting tool includes a terminal body which is adapted to engage a bottom obstruction. The terminal body mounts a plurality of wedge members for movement radially outwardly as the wedge members are moved downwardly by an internally mounted piston member. The piston member is moved downwardly by an actuating cylinder which is attached to the whipstock. A spring member is positioned between the actuating cylinder and the piston to provide more uniform engagement between the actuating cylinder and the piston as the actuating cylinder and piston move downwardly thus moving the wedge members radially outwardly into engagement with the casing.