This page is credited in full to Dave Cushman who created it. His voice is expressed in black colour text and any additions or comments in blue belong to myself. Credit: Dave Cushman’s website.
National Bee Hive ‘Crown Board’ or ‘Coverboard’
What our American friends call an ‘Inner Cover’
The crown board is a method of closing off the top of a bee hive so that the main protective roof can be easily removed.
National Bee Hive Crown Board Use with the rim downwards for bottom bee space or with the rim uppermost if top bee space is required.
The holes shown are to suite the standard porter escape.
Porter Escape Holes gives methods of cutting such holes. For normal use a single 33 mm central hole proves to be adequate.
9 mm plywood is specified owing to it’s greater rigidity and freedom from warping. This durability outweighs the small cost saving of using thinner material.
9 mm is specified for the thickness of the rim material, but commercial supplies are often of 8 mm thickness, using 8 mm is unlikely to cause any problems.
Assemble using a waterproof PVA type glue and 16 mm pins or staples.
Many old specifications for this item quote a rim depth as small as 6 mm. In practice this causes much trouble due to brace comb that has been inadequately cleaned from the upper surface of the top bars.
Versions of this board will be found with bee space on both sides of the main panel. Many commercially available types use this method with the panel fitted into rebates in specially machined rim pieces. There is no benefit in having this reversible bee space… It has only become common as it is a simple way of stiffening a 6 mm plywood panel and thus keeps down production costs.
The version as drawn above is both simple and durable. If petroleum jelly is used on the rim and linseed oil is used on the main panel the item will give many years of good service.
My only change would be not to include the holes. A solid Crown board works so much better. 😉