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Balsa Wood Tower Project


ar93

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Hi! This is one of those tower projects again.

 

My tower is due in about a month, and I'm completely lost as to how I should build it. I know that the brainstorm process will take a while, and the building even longer. Here are the requirements I've been given:

 

1. 35.0cm tall tower that will span a 20cm x 20cm hole.

2. The top of the tower will need to hold a square block that is 5cm x 5 cm. I assume, therefore, the top of my tower should be 4.5~4.75cm across to be on the safe side.

3. constructed ONLY using wood and wood/superglue

4. Pieces of wood can be 1/4" by 1/4" max. Dowels may have maximum diameter of 1/4 inch. (I doubt I'll be using dowels. Square pieces are easier to find.)

5. Wood may not be laminated or coated with paint/glue/etc.

 

The square block mentioned in #2 will support a chain that goes THROUGH the tower. Weights will be added into the bucket (that is hanging from the chain) until the chain touches the inside of the tower or until the tower collapses.

 

The maximum load supported will be 15kg (that mass includes the block, chain, bucket, etc).

 

The tower will be graded on structural efficiency.

Efficiency = load supported / mass of tower

(My tower should be as light as possible while supporting the heaviest load)

 

So far I've researched a bit and come up with these conclusions:

1. Triangles are the best shapes in terms of support. I'm going to have to incorporate it into the trussing.

2. Arches are even better! (However I think it will be difficult to make arches given time constraints, and it's too complicated. I'm not a physics buff.)

3. Boxes are bad? No boxes?

 

So first of all I need to decide on the base. In order to save weight, I should use a triangle, but I think that it might not be a good idea. It's supposed to span a square whole. If you put a triangle on top of a square, then one of the legs is going to have to span the entire width. The other two will be supported much better than that one leg, so it'll be prone to breaking more easily because the weight supported isn't spread out evenly. In this case, would it be better to make a square base and sit it like a diamond over the hole?

 

I'm debating whether the tower should be entirely pyramidal or look like one of the chemical bottles: pyramidal on the bottom and have a vertical neck. Should it be very pyramidal (lower slope) or more narrow and vertical? If I'm going to have a vertical 'neck' on my tower, should it be short or long?

 

What kind of cross-bracing/trussing is best? Triangular trussing or something that looks more like the Pratt trussing? Cross-bracing for the vertical neck?

 

Any help would be very much appreciated. I'm sorry if my questions are too general or I'm asking a broad question. Like I said, I'm not sure how to start.

 

Complicated math formulas (such as Euler's Theorem, is that what it's called?) will be unhelpful to me, also. ><;;

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  • 1 year later...

Is there a limit for the diameter of the base? If not, then use a square (a triangle will be prone to tipping) that is larger than the hole.

 

The lower the slope of the tower, the more stable it will (generally) be, but the steeper the slope, the taller the tower will be, unless extra materuals are used.

 

Instead of angling the sides of the tower, why not make the sides move inward in steps, like the Myans (Or was it the Aztecs?) used to do? That would make the tower much easier to build.

 

Would you be allowed to 'weight' the bottom sides of the tower? That would move its center of gravity downwards, making the tower more stable.

 

Hope this helps!

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