I devised this top cover in order to combine top entrance options with enough space to fit pollen supplement patties.
JPG of Flat Cover plans
I made some inner covers like that, real handy for pollen pattie feeding. The problem I came upon is that they will fill that space with burr comb and make getting the covers off real difficult. They also take a lot of scraping and cleaning.
I wonder if a piece of heavy plastic would solve that?
Bullseye Bill in The Scenic Flint Hills , KS
I use about the same thing.
1)the top is construct of plywood.. those cracks ain't so good if you are in a shb area.
2)I provide a notch for a top entrance at the front side of the rim.
3)I drill a large hole in the center of the plywood and glue and nail a square of scrap plywood block drilled with a slightly larger hole to allow for a boardman type feeder.
I have always assembled my supers so the frames are even with the top edge of each super, hence, all my bee space is below the frames on each super. Probably why I have seen a few pieces of burr comb attaching the flat tops with bee space rims to the frames, but not so much as to cause much trouble, yet. Of course, its always the plastic frames that get burr/brace comb wherever they are.
the depth of the frame rest should be determined by your choice of either migratory covers or inner cover/outer cover. If the frame rest is cut shallow and the frames come almost flush with the top to the box then this is a inner cover/outer cover set up. If the frames bottom bars are almost flush with the bottom of the box then this is a migratory lid set up.
I personally like to allow a bit more space at the bottom of the stack but still wish to use a migratory cover, so the rim is like building in that bit of space that an inner cover would provide. As you and Bill so correctly suggest it also make feeding pollen patties a bit easier.
the addition of the boardman feeder makes feeding quick and you can keep the syrup can right above the cluster. Remove the bottle, staple on a bit of screen and you have good ventilation in hot weather when you move hives.