The bee space, that little gap which the bees respect, approx. 0.25ins
(6-8mm), has been known for a long time (Lorenzo Lorraine Langstroth, 1852,
the "father of modern beekeeping").  However, many beginners do not realise
just how important it is when it comes to handling.
Here in England we still have boxes with both deep and shallow rebates to
give top or bottom beespace respectively.  Both work well but using a
mixture is a disaster.  Either bottom bars are glued to tops or the gap is
doubled and filled with burr comb.  In the struggle to free such combs a
normally happy stock can be turned to an aggressive one.
As an old hand I have been called out to many unhappy beekeepers who find
their bees unmanageable.  A few bees are difficult but in the main the fault
lay with the beekeeper and his equipment, generally glued up due to wrong
spacing.
Manufacturers are not always helpful.  One finds excluders with fillets on
both sides. To fit both top and bottom spacing they should be flush on one
side with a quarter inch fillet on the other.  An eighth of an inch short on
super depth can spoil matters.  Supers shrink with time and a simple remedy
is a thin fillet nailed to the bottom.
With the correct beespace supers lift off cleanly, excluders are not clogged
and top bars stay clean, all in all a treat for the bees and the beekeeper.
All very obvious really.
Regards         Sid P.
_________________________________________________________________
Sid Pullinger                    Email :  [log in to unmask]
36, Grange Rd                Compuserve:  [log in to unmask]
Alresford
Hants SO24 9HF
England