Top bar nuc dimensions question

That's just a few inches longer than what I built. It is also serving as my swarm bait hive at the moment. I wanted it to be longer than a standard nuc so I can either divide it in 2 or put the glass jar feeder in the nuc.

Check out this thread http://www.beesource.com/forums/showthread.php?295595-Nuc-to-top-bar

I built a short tb nuc 7 frames +wiggle room and added a slot in the back to slide in a board man feeder. The thought was the feeder is far from the entrance so less worries from robbers. I glued on a couple of angle cut scraps so that when not using the feeder a block with angles cut into each end could slide dovetail style over the feeder hole.
My suggestion would be to make one of your ends removable if you can without too much trouble. I opened mine, which is much shorter than yours, and noticed than at least one of the combs is attached almost top to bottom on both sides. the limited access, due to the length, means it will be hard to cut out.
Fabian

21 inches is long enough to be used as two nucs, or one small hive. I have an 18" nuc with entrances at both ends and a follower board which allows me to use it as two small nucs, or one larger one. I also have a smaller nuc/swarm trap/inspection box as shown in this post http://www.beesource.com/forums/sho...Riding-Hood-Workbox-Nuc-Swarmbox-Top-Bar-hive I am really liking how it works.

SteveStevenson said:

I'm going to build a top bar nuc to use as a swarm trap. Thinking about making it about 21 or so inches long and the same width & depth as my top bar hive. Any input would be appreciated.

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My traps average 10 bars long and I've been successful catching swarms with them. I build my top bars 17" long so I can swap them into a Lang with simple modifications. You want about 40 liters volume so depending on how big your top and bottom are will effect the length. Do the math, just goggle "Volume of a Trapezoid". Below is a link to my drop box with pics of them, I have modified the tops from telescopic to migratory since the pics were taken. As an experiment I built a trap yesterday like a stud space, 20"X4"X58". It holds 10 deep frames and I'm hoping to catch a swarm from a building where the ferals swarm to stud spaces.
Colino
https://www.dropbox.com/sh/34l58y2kbcg9pil/OlZmxiIvXh

I just built four nucs/traps that will hold 12x 1.25" wide bars + a 3/8" spacer/optional top entrance. Inside dimensions are 15 3/8". These are the same "foot print" as Les Crowder hives which are what my 48" hives are.

If you figure out the internal volume of your particular TBH, then you can adjust the lenth to match whatever you want to. You will know that this many bars or inches is equivalent to a deep, a medium, a swarm trap, etc. In the end doing a little math makes it easier on you. Make a table for volume vs lengh for your model, put it in your bee log, and then you will have a handy reference.

I made mine to the dimensions of my hives, 17" top by 6" bottom, 11 bars long. Didn't catch any swarms, but did a split of 3 bars brood plus a cutout swarm cell mid summer last year. They filled the 11 bars by winter, overwintered well, and are now moved into a 48" long hive and are booming. I think that 10-12 bars is a good nuc size for tbhs.

+1 on what RCorl said, but I think that you need to be a bit longer for a swarm trap. My hives are about the same size as RCorls, and to get 40 liters I need a 24 inch box. I have a bunch of boxes out between 12 and 18 inches, but last year the only successful box was a 24 inch nuc in my back yard. If I get the same results this year I'm only going to use the little boxes for splits/nucs. But I'm hoping to get some action in the smaller boxes this year, they are faster and cheaper to make, and easier to store. Maybe this year there will be more swarms and those little ones see some action.

My traps range from 8 - 15 bars. I try to leave a shim at one end in case I am slow in finding them, or they are fast in building. That way you can still get in.