Top Bar Thickness?

[TheCheatOSX]

I'm pretty much done on the planning stages of my TBH's. See the Equipment Forum for the Sketchup File (http://beesource.com/forums/showpost.php?p=287827&postcount=21).

My question is what thickness top bars are you guys using? These will be standard 19" long and 1.25" wide. I have them spec'ed out to 1" thick right now but it would be a lot simpler to use the stock the boxes are built out of instead of cutting down 2x4s. Is 3/4" stiff enough?

[Tim Hall]

Chris,

I plan to use 3/4" stock for my topbars (my lumber just arrived today!), but I don't really have any experience with this. Hope fully someone else will chime in here.

However I took a look at your SKP file, and noticed you have slots for a removable bottom board. I would be concerned that a thin piece of sheet material spanning the full length of the hive, hinged only on two sides, will start to sag and fall out over time. You may need to reinforce the bottom board with battens.

[TheCheatOSX]

Good point on the bottom board. I'll be using some corrugated plastic (stuff used for yard signs) for the board. I'll see how it sags. I might glue a small strip down it's length perpendicular to stiffen it up. I've also uploaded a new SKP file with my latest refinements. Same Link (http://chris.norrick.com/bees/Double_Wide_TBH.skp) I added in a couple of back holes in the corners for doing spits and added in the follower boards.

[stangardener]

i make top bars 3/8" thick. that way they are interchangeable with lang equipment.

[Michael Bush]

For the Lang style equipment I made them 3/8" to leave a bee space on top. For the KTBH I made them 3/4" as that was easy to do. They both work.

[Tomas]

My top bars are 5/8 of an inch and I haven't had any problems with them. Sometimes I'll get one that is only half an inch because it comes from the last part of the piece of wood I'm cutting. I haven't had a problem with these either (rather take advantage of it than let it go to waste). Knots, however, can give you a problem.

Tom

[TheCheatOSX]

The design is basically a wide Lang. I don't plan on using it with any lang equipment (except for maybe installing a nuc) but it's nice to have the option if I need it. Since I won't be using it as a lang, 3/4" it shall be. It will really simplify the woodworking. Thanks for the feedback.

[Beaches' Bee-Haven Apiary]

I know this belongs in Tailgater, but are you running Leapord?

-Nathanael:cool:

[BWrangler]

Hi Guys,

Some thoughts on top bar thickness.

There are a few ways to loose a comb. Flex the comb and it's gone. Or flex the top bar and it's gone.

Rather than think thickness, thick rigidity which is a affected by thickness, length, load and top bar configuration. A larger comb, moving or stacking hives, and setting on the top bars all increase the loading.

So, do a test. Build a prototype. Support it on its ends. And apply pressure in the middle. If you don't like the way it flexes, go thicker.

I used 3/4 inches for my first 22" long bars. They had a 1/4" saw kerf used to make a "T" type top bar reinforcement. That cut, even with the wood slat glued in, unacceptably reduced their rigidity. Increasing the thickness to 1" stiffened it back up.

I've seen shorter top bars that are 2" thick. That is probably an overkill.

Regards
Dennis

[buckbee]

Winter insulation is also a factor - the thicker the better if you don't have additional insulation between top bars and cover - but 2" does seem excessive.

[ottawabee]

I ripped 2x4's to width - plenty stiff, using a table saw, and then a chop saw to cut to length. build a complete hive in a morning