I recently finished constructing my first two top
bar hives based loosely on construction diagrams
suggested in posts to sci.agriculture.beekeeping.
(They are "sloped" sided hives 18 inches wide at
the top, 7 inches wide at the bottom, 10 inches
deep, and 36 inches long, each holding 25 top
bars.  These dimensions allowed cutting two
complete hives out of one 4x8 sheet of plywood.)
While some web sites suggest there is no need for
queen excluders in TBHs, I've been wondering if a
simple queen barrier would help concentrate brood
rearing toward the front entrance of the hive?  I
understand that before wire excluders became
commonly used with Langstroth hives, some
beekeepers accomplished the same result by
centering a rectangular sheet of thin wood on top
of the brood frames, leaving an inch or so of
space around the outside edges.  Could the same
principle be used in a TBH -- vertically, of
course, instead of horizontally -- such as nailing
a piece of masonite to hang from a top bar, with
gaps for the workers to move around it along the
bottom and/or sides?  I realize I could simply cut
a perfectly good wire excluder to fit, but I'm
looking for an easier (and cheaper) way to
accomplish the same result.  Any thoughts?