bar length: a new perspective

[dmcdonald]

I had an email exchange with Marty Hardison a few days ago. He brought up an argument in favor of short top-bars, which hadn't occurred to me before. Nor had I seen it in the discussions here.

Here it is. Bees like to build curved comb--the comb is not typically a perfect plane, but is somewhat cupped. The longer the bar, the greater the total divergence from a a plane, and therefore the more trouble (for the beekeeper) with trying to fix combs which don't stay tidily on their own bar.

But, with a shorter bar, you're getting a shorter section (from end to end) of the natural curve, and therefore it coincides more closedly with the straight line desired (for ease of management) by the beekeeper.

(Think of the tangent of an arc. Draw perpendiculars from the two ends of the tangent toward the arc. These perpendiculars increase in length as the length of the tangent increases. The tangent is the bar, the arc is the comb. This is the mental picture that makes Hardison's argument convincing to me.)

He's passionate about this, because he thinks a lot of beginners who start with long bars get frustrated and quit on account of comb management troubles.

He also would agree that really long bars are more prone to comb failure, and says that the longer the bar, the more severe the taper of the hive needs to be, to mitigate stresses on the comb. With a short bar, you can have hive sides which are nearly vertical, and with a long bar, you'll need more sloped sides. In light of this, I'm not sure what to make of the Tanzanian hives with long bars, and vertical sides, and operating in hot weather. Maybe it comes back to the issue of entrance size--a big entrance on such a hive would be a disaster, because the bees couldn't control the airflow.

[This message has been edited by dmcdonald (edited March 08, 2004).]

[Cinnamon]

Hiyas,

define 'short' and 'long' please?

Cinnamon

Ps.: does he have more bars to compensate for space lost, and if so, how many?

[dmcdonald]

Short and long are mystical terms.

I guess short would be 16 inches, the length Hardison uses. Long would be, say, 20 inches or more.

Yes, he does end up using more bars than he would if the bars were long--his hive is about 40 inches long, accommodating (I think) about 27 bars. But the overall volume isn't huge, compared to some TBH's. You can see construction details for his hive at my site,
http://home.att.net/~mcdonald/bees/hive/

[This message has been edited by dmcdonald (edited March 08, 2004).]

[Michael Bush]

My latest hive's bars are 15" on sloped sides that are 3/4" thick, so the bar that is exposed in the hive is actually only about 13" (allowing for the angled side being about 1") The comb then should be about 12 1/4" wide (allowing 3/8" beespace on each side).

Last year's comb collapse convinced me to go with shorter bars. But it's true the ends of the comb had a curve toward the front of the hive. I thought perhaps it was partly due to the 1 1/2" spacing I did too. So I narrowed it back to 1 1/4" (I have small cell bees or I would recommend 1 3/8"). I wonder if the curve of the top of the comb (I assume we are talking about a curve in the top edge of the comb across the bar) is party to stiffen the sheet of comb. An arch would be more stiff than a flat comb.

My "control" test is a long bar with shallower comb (6 5/8" instead of the 9 5/8" I did last year)

[limulus]

I have built some 1.5" top bars with a slight curve to them, 3/8" toward the front on 16" bars. They were a bit of a pain to make, I cut them out on a band saw, but are not that difficult. It was simple to bend a spline like MB is using this year down the centerline by tackink one end, then the center, then the other end, then add a couple to stiffen. I am going to try them toward the rear in the honey storage area. I made a transition bar (flat on one side and curved on the rear to match it up with the straight bars. I do not think the spacing problems will be too bad in the transition as the bars are not all that curved. They hang nicely, I was worried that thay might want to roll so simulated a heavy comb by fastening some screw eyes to the bottom and hanging some heavy objects.

[Scot Mc Pherson]

David
Actually I consider 16" to be the break point. Shorter than 16" being short, longer than 16" being long. Marty likes to use top bars that are between 14"-16" long. I also have somewhat regular exchange with Marty. And through discussions with Marty its interesting to find out that he has regular exchange with lots of memebers of the board, yet he isn't a member of our little group.

One of the sites Marty likes to recommend is your own site for inital TBH designs. Thought you might like to know that.

I am still in the process of ripping precise top bars from 2x4s. It takes a LONG time, especially when I only get 30 minutes here and their between shifts at work and managing family. Anyway, I rip 3 bars from a 18" long piece of 2x4. My hives are 48" long, and the top bars are 32-33mm in width. That's roughly 37 top bars, times 4 hives. Next time I am going to spend the extra money for 1x2s. I saved $80, but its taken me way too much time to finish building the hive.

The point was, my hives are roughly 16" x 10" with a 8" bottom board and 48" long, roughly being between 90-100 liters if I recall correctly. I'd like to experiment with other sizes, but I didn't really have the time to mess with building different sizes. They aren't exactly meeting my own "perfect" specifications either, but that was also due to time and cost. I needed fairly ready materials from new lumber so I settled with 1x12s 1x8s and 2x4s for material and just cut them to length essentially. Since the dimensions are smaller than my own designs, I can build a new hive over the summer and build it nicely the way I really want and not how time and cost demands. I barely could ( and really couldn't actually ) afford to start this year, but I wasn't going to have a repeat of the last 6 years. It'll still be nice to have my bees. They'll be here sometime this month.

[This message has been edited by Scot Mc Pherson (edited March 08, 2004).]

[Scot Mc Pherson]

Oh yeah. My top bar design is a littel different and it is the result of bad planning going right.

I was planning on building top bars with slopes to them and waxing the center point of the bar. Well my table saw broke and I had to borrow a friend's table saw. His guide metal (the flat piece next to the saw blade) was warped and so I had to abandon that idea. I decided on a spline/kerf, and so I cut the cetner out of the btop bars. Well the shims I had left over from the ripping ended up being the wrong size and so I gave up on that idea too, but had top bars with grooves cut out. The metal piece that was broken on my friends table saw was in pristine shape on my own saw, and so I swapped it out, I cut the slopes into my top bars, and left the shallowest of cuts into the cetner from that previous kerf cut. Whas I have is a 1mm or less shallow grove at the center of the slopes that I am rubbing beeswax into. Whne I can take pictures I will post them, its actually a rather interesting screw up that I think will work very well.

[Oxankle]

Fellows:

I find this all very interesting. I have built three TBH's--one Tanzanian 20 inches wide x 3'9" x 11 & 1/4 deep, plus a Crowder hive and a Hardison hive.

I have put splined top bars in each, painting the splines with hot wax. After reading about the difficulty of getting the bees to accept deep splines, I made sure that the splines were less than a quarter inch deep. The Crowder hive has splines that are uniformly 3/l6", pretty shallow.

I can understand the theory behind curved top bars, but it seems to me that either a top bar super or a longer hive is more useful and practical than long, curved bars.

On material costs: Framing crews on any big home-building job nowadays are throwing away tons of pieces of 2x4, 2x6, 2x8 and even 2 x l0 and l2 material up to 6 feet long, and some even longer. My son in law, a builder, brought me a load of it.

If you pick thru this there is much spruce, which cuts and works almost as good as white pine. There is plenty of good pine and fir, too, but I like the spruce for top bars. I cut them three quarters of an inch thick,then resaw these stips to and inch and three eighths. I cut the kerf for the spline and then cut them to length.

If you have any way to resaw 2x material, or are willing to use 2 x material for the bottoms and sides the entire hive would be free for the taking at home construction sites. I do use 2 inch material for the end boards, screwing the whole thing togetether with drywall or deck screws.

Since I have had to cut all my sides and bottoms from purchased 1 x 12's each hive costs about $16 before I start the roof cover.

Now if the bees will just cooperate!
Ox

[BerkeyDavid]

I ripped my top bars from spruce 2x4's as well. The key is to have a good rip blade and a well-tuned fence. The fence needs to be perfectly parallel with the blade. Then after ripping them, I cut to lenght. On one of my hives i ripped them to just over 1/2 inch so I could get one more billet from the 2x4. The other hives were about 3/4". Then I cut down the first 8 bars to 1 1/4" for the brood.

[DeeAnna]

Bump. This discussion from 2004 might be of interest to folks currently reading the TBH forum and interested in TBH design.

[sqkcrk]

Is anyone building TBHs using Tom Seeleys data on cavity size preeferences by swarms? Supposedly swarms prefer a cavity about the same size as a deep 8 frame super. Do folks use those dimensions in thewir TBH designs?

[Delta Bay]

Yes I did. Eight bars with a follower board in my hive is equivalent to an eight frame deep. Just a different shape.

[WLC]

Yes.

We built 2 TBH 'swarm traps' using recycled styrofoam containers of approximately 40 L. The entrance was about 1 1/4". The bars are 11" long with a waxed string starter guide.

I think that an 8 frame deep is too small. His swarm traps were 15x15x14 inches.

[100 td]

I don't know the length of this bar, but it appears to be about 20" and all looks good. Maybe the comb is 16"?

[Adam Foster Collins]

When I was first designing my top bar hives in the winter of 2009, I was asking questions here on bar length and at that time, Michael Bush advised a bar length of no more and 18 inches. He said any longer than that and the bees start wanting to curve them. So I figured I'd benefit from his years of experience and went with that. My combs are about 2/3 the size of a deep frame, and I haven't had any problems with curved comb, cross combing or comb collapse.

Adam

[My Local Bees]

I have made top bars from 16 inches to 22 inches. The 22 inches were too long and difficult to handle. The 16 inch top bars seemed too short; I have settled on 19 inches after listening to Sam Comfort.

Doug

http://mylocalbees.wordpress.com/

[Adam Foster Collins]

I can see the interest in 19 because of the lang frame length. But unless the top bar hive is a tanzanian - or straight sided - then the 19" bar doesn't allow you to put a lang frame in. It does, however, allow you to put a top bar into a lang hive...

Adam

[David LaFerney]

I ripped my top bars from spruce 2x4's as well. The key is to have a good rip blade and a well-tuned fence. The fence needs to be perfectly parallel with the blade. Then after ripping them, I cut to lenght. On one of my hives i ripped them to just over 1/2 inch so I could get one more billet from the 2x4. The other hives were about 3/4". Then I cut down the first 8 bars to 1 1/4" for the brood.

Actually if you cut to length before you rip it saves a lot of work, and it is safer and easier to rip short lumber than long. A good rip - or combo, which I prefer - blade does make a big difference though. However it is usually better for your fence to have a tiny bit of lead - farther from the blade on the outfeed end - than to be perfectly paralel. It reduces burn, bind, and kick back.

[NY_BLUES]

I can see the interest in 19 because of the lang frame length. But unless the top bar hive is a tanzanian - or straight sided - then the 19" bar doesn't allow you to put a lang frame in. It does, however, allow you to put a top bar into a lang hive...

Adam

I did this. I put a few of my top bars into a strong lang hive to get the comb started. They did start the comb, and when I had a few bars with combs about 5"x6", I moved them into a tbh that I had set up as a swarm trap.

[JRGN]

Hey fellows, like the discussion been looking and reading what everybody has to say and have learned alot so far, I myself have built a TBH and the top bar is approx; 20" but the follower is rite at 16" also I designed it with a 10 frame lang for the rear, also let me know if I am going in the rite direction is that for the brood bars they are cut at 1 1/4 wide and for honey production 1 5/8 wide, let me know what you all think. Jr.