GLUE!

[yellowbird3]

Obviously we need glue. It seems as though everyone has a preference, but never tests with any others. First of all I would REALLY like to know what percent of the Tower’s (Boomilever; elevated bridge; ect.) weight is glue. Also, I am extremely interested in finding a brand (or type) of glue, which, whilst being strong in it's bonding abilities, does not burden the structure with excess weight. Any advise or suggestions for a particular glue (and methods of using or applying glue) would be much appreciated!! This up coming year I plan on doing experiments testing glues and ways of gluing, but as all experiments go, research is the step after the problem thank you!

[fishman100]

First, try reading through the forums/wiki, because glue has been discussed numerous times in the threads throughout the years. Most of your questions can be answered with a simple search, but I guess I can answer them for you here.

I'd say about 10% (or less) of a good structure's weight is glue (any builders care to verify this?). In order to use such little glue, an applicator can be used. This can be nothing more than a toothpick or a scrap piece of wood and you can easily build your own. One applicator that appealed to me was a bent paperclip attached to a stick of wood for gripping. The ends of the paper clip could be bent to control the amount of glue that it picked up. (I would provide a link, but I can't find the website...)

The BSI CA brand seems to be a good choice, but I have not experimented with other brands before. One competitor used this type of glue and gave some advice about gluing and this glue in her Wiki page.

[iwonder]

I've always used cyanoacralyte(super glue) Aia has a nice write-up in her boomilever guide(on the wiki), and there's a nice pdf on glue techniques on the soinc website under towers. From what I've been told, the glue shouldn't add much more the .02-.06g to a structure, but someone else may have a better idea on that.

[jander14indoor]

See this writeup on glue: http://www.soinc.org/sites/default/file ... weight.pdf

10% of structure weight in glue is probably way high. The flying events should be on the order of 1-2 %, I have data on that. The structure events are probably higher because there are just more joints, but it takes amazingly little glue for a well design and executed joint.

The one exception to this MAY be (based on past discussions) the Boomilever tension joint to the base. This is because there is just so much force through a small section. But careful design and execution can pay off here too.

Jeff Anderson
Livonia, MI

[retired1]

How much glue is enough? That depends on the joint. I have seen towers that used a medium CA which does not soak in rip the outer layer (ring) off because the wood was not strong enough in that direction. Now, 90 degrees away, it would have held. (there face of the stick) But joints in balsa with CA are horribly weaker because the glue wicks deep into the wood and leaves nearly nothing on the surface. This is a problem with thinned out Ambroid also. Play with scraps and find out what works best for you.

For CA, I had the students put a tiny drop on aluminum foil and then gently touch the stick to the glue. A circular motion helped if it was thin. Took a lot of work to get builders to use the right amount of glue.

For a tower , I will guess that it is 3-5%, but that is going to depend on stick weight and number of joints.

[Aia]

When I built towers in 2007, I recorded the weight of every piece of wood I used as I went along. After finishing the tower, I weighed the resulting structure and compared that value to the sum of the weights of all the pieces.

In a 5g tower, I generally found that ~.1g of the tower's mass was glue. That's around 2%.

I would guess that boomilevers have a higher glue percentage. This is because of features like the base and distal end connection, which may require more glue or heavier glues to deal with the stress.

[Faustina]

I have data from a tower I built last season.

Tower without glue = 9.22 g
Tower with glue = 9.70 g
Glue = 0.48 g

So that's 4.95% glue by mass. I think this is reasonable, but not great, for a tower.