Building the Hive – top bar
Each top bar has a spline along its length.
The splines face into the chamber and rib its ceiling.
A spline (hopefully!) guides the bees to build a single comb along the length of the bar
and perpendicular to the long axis of the chamber.
A beekeeper can then lift out each bar to inspect or harvest comb one by one.
And that's the quintessence of a top-bar hive.
The bar width is important for removable comb as well.
Some sources recommend
1 3⁄8 and others say
1 4⁄8 instead.
Mine are the latter because that's what Home Depot carries
and because my workshop lacks a table saw to rip the wider to the narrower.
For the guides,
I simply glued on 1⁄4-square dowels in the absence of tools for anything