Designs

[mrsteven]

well im asking when looking directly at one side of the tower so you clearly see an X, if you see the 1/64th or 1/16 facing you.
so which side is being shown, the thicker or thinner

Ive used 1/64th and you pretty much always have the 1/16th side up so you have a better gluing surface.

so, just to be clear, when you look at a side of the tower you see the 1/16th part?

[lucwilder42]

well im asking when looking directly at one side of the tower so you clearly see an X, if you see the 1/64th or 1/16 facing you.
so which side is being shown, the thicker or thinner

Ive used 1/64th and you pretty much always have the 1/16th side up so you have a better gluing surface.

so, just to be clear, when you look at a side of the tower you see the 1/16th part?

http://gallery.scioly.org/details.php?image_id=3368 like this picture but with the pieces being half as thin. you couldn't do it any other way

[Balsa Man]

I answered in my initial post- "flat, 16th dimension parallel to the legs."
lucwilder is absolutely correct; it doesn't make any sense the other way. See Image Gallery, Bridges 2009; look at the bracing along the top side

[Balsa Man]

The tensile strength of "high density" balsa is pretty amazing. A little real test data - 1/16th width, from a 3"x36" 1/64th sheet at 8.6grams, almost 2.1kg. The range of (3"x36") sheet weight that "should work" at 1/16th is from the low 7s up.

When you say that the range of sheet weight that should work at 1/16th is from the low 7s up, are you referring to a 1/64th sheet cut into 1/16th pieces, or to a 1/16th sheet? I initially interpreted it to be the latter, but now that I think about it, that wouldn't make much sense because there wouldn't seem to be an advantage using 1/64th.

Correct (when thinking about it later)

[mrsteven]

Sorry, that was a bit embarrassing I should really start drawing things on my blackboard before I ask ^.^

[Balsa Man]

Sorry, that was a bit embarrassing I should really start drawing things on my blackboard before I ask ^.^

Not a problem Translating words into a picture/understanding; drawing things out is always a good idea.

[thsom]

for 1/16 by 1/16 balsa is a density of .4 grams per 36 inch stick sufficient for bracing or is it too light and if sufficient than is .3 okay as well or is that way too light?
for 1/8 by 1/8 balsa is a density of 1.6 grams per 36 inch stick sufficient for main legs or is it too light and if sufficient that is 1.4-1.2 g okay as well or is that way too light?
for a division c tower

[lucwilder42]

for 1/16 by 1/16 balsa is a density of .4 grams per 36 inch stick sufficient for bracing or is it too light and if sufficient than is .3 okay as well or is that way too light?
for 1/8 by 1/8 balsa is a density of 1.6 grams per 36 inch stick sufficient for main legs or is it too light and if sufficient that is 1.4-1.2 g okay as well or is that way too light?
for a division c tower

There's really only one way to find out

[Balsa Man]

for 1/16 by 1/16 balsa is a density of .4 grams per 36 inch stick sufficient for bracing or is it too light and if sufficient than is .3 okay as well or is that way too light?
for 1/8 by 1/8 balsa is a density of 1.6 grams per 36 inch stick sufficient for main legs or is it too light and if sufficient that is 1.4-1.2 g okay as well or is that way too light?
for a division c tower

There's really only one way to find out

Right-on, lucwilder.
Couple additional thoughts:

First, I don't think anyone is going to share information as specific as you're asking for on what does and doesn't work.......

Second, re: the legs:
At full load, chimney and base legs see different forces (more in the base because of the angle), so what would work in the chimney might not in the base. Just stating density and size doesn't allow you to say it it "will work." Review discussion on column failure. At a given density and size, it is the exposed culumn length (the length between bracing sets) that determines if will carry a given load. I will tell you, that at 55cm (chimney with no bracing between top and bottom) it won't even come close, and that if braced at, say every 2cm, it will be grossly over-engineeded. 1.6, 1.4, 1.2 (and 2.0, 1.9, 1.8, 1.7, and 1.1, 1.0, 0.9, 0.8, etc.) will all "work" - the question is at what bracing interval....that will be different for each.

Third, on the light 1/16th, 0.3/0.4 gr/36" is VERY light stuff. On the one hand, put a 5cm piece (~the length for in the chimney) between your fingers and push in; almost no force to bow/break it. On the other hand, it doesn't take much strength/force to resist the very beginning of bowing. There really is only one way to find out. I assume you're talking about for use as ladders (working in compression). For tension (Xs/Zs), very small glue area, very low tensile strength, very soft wood = will shear away under very low force.

[twototwenty]

I am sure this has already been discussed, but I do not have time to wade through all of this thread...I apologize, but I have to ask:

-When attaching the legs of the base to the corresponding main shafts of the chimney, 1) do you use lap joints or butt joints? and 2) what angles should the two pieces of wood form, ideally?
-What are people doing as far as hieghts for the towers, with the new incentive for having a taller tower?