Horizontal beams (automatically)?

[Marcus Macauley]

I know this has been asked before, but I haven't found an answer:

Is there a way to automatically make all beams flat, or to automatically  
make a certain beam flat?

Searching the documentation and lilypond-user, I found two methods,  
neither of them sufficient.

The first method,
   \override Beam #'damping = #100000
, should make the beams horizontal, according to the documentation --
http://lilypond.org/doc/v2.9/Documentation/user/lilypond-internals/Beam.html
and
http://lilypond.org/doc/v2.9/Documentation/user/lilypond-internals/beam_002dinterface.html
-- but in fact they remain slightly slanted. (For example, one end of the  
beam sits on the staff line, while the other end of the beam straddles it.)

The second method (as suggested recently by Trevor Baca on this list),
   \override Beam #'positions = #'(4 . 4)
, works fine for individual beams, but is impractical for a whole piece;  
you'd have to manually set the position of each beam.

Any other ideas?

Marcus