7.1.5 Cross staff stems

Chords that cross staves may be produced by increasing the length of the stem in the lower staff, so it reaches the stem in the upper staff, or vice versa.

     
     stemExtend = \once \override Stem #'length = #22
     noFlag = \once \override Stem #'flag-style = #'no-flag
     \new PianoStaff <<
       \new Staff {
         \stemDown \stemExtend
         f'4
         \stemExtend \noFlag
         f'8
       }
       \new Staff {
         \clef bass
         a4 a8
       }
     >>