This option is the same as the Use spindle main direction option. The only difference is that the user can set any user defined direction instead of the spindle main direction.
To define the direction, push the "…" button and enter direction coordinates. Or select a direction by point selection in your graphic area by pressing the "…" in the popup window.
Hit the "Advanced" button for advanced options
and the advanced options windows pops up
Go to
Gradual side tilt angle change