I built my TBH with straight sides, 20" top bars, and 10" deep. At this point, if I were doing it over, I'd probably make them smaller, but with 5 hives and a couple hundred top bars already built and bees in the hives, I'll probably stick with it for a while (forever?)
So, about comb attachment. I tried my trusty old hive tool, but wasn't happy with the results when cutting comb free from the sides. It is a bit thicker than is really needed for a TBH and it tends to grab a wad of comb at the cutting edge and tear some comb. Also the cutting edge is on the end, so it's impossible to cut the comb from bottom to top, which is the only logical way to do it in a TBH. I wanted a knife that is sharp and thin to cut the comb free from the sides. So, I took an old hacksaw blade and sharpened both sides on my grinder like this: \_______/ With both bevels on the same side of the blade.
So there is a bevel to use on either side of the hive. The blade is very thin, so it doesn't grab wax much. It's long enough to reach to the bottom of the hive easily.
I put a handle on it by cutting a dowel lengthwise, did a bit of hand-chisel inletting, and riveted it through the hole already in the blade. The blade goes into the handle about 3".
Works like a charm. It is stiff enough to insert between top bars and twist to break propolis free. It's very light and quick. And it cuts the comb right at the sides of the box. My old hive tool is still useful for other things, but has been replaced for everyday use at my hives.
And it was cheap. [img]smile.gif[/img]
Next time I fire up my lathe, I'll turn a nicer handle, but only because I want to.