is there a way to manually rotate the palette knife brush? without the 6d pen? ive opened the brush angle window and none of the functions are a manual adjustment.
I know its an old question, but maybe somebody is still looking for an answer :) I have an old Intuos 3 tablet with a default pen, and the only way to rotate the palette knife (other than jitter, or setting expression to - very chaotic - 'direction'), that i've found is setting that expression to 'wheel', and then setting the angle manually in 'mouse' tab. Now i can smear the paint vertically, yay :) (just remember, that the setting is in %, not in degrees, so i.e. vertical setting is 25% /75%:)
(btw, its very strange, that it's still a problem...)
Set expression to angle in the angle menu and you will be able to rotate the stilus and angle of the palette knife. Try holding stilus rather angled towards the tablet (not in a right angle)