Engineering Challenge: Create a Balsa Wood Structure to Hold 3 15lbs. Weights!

[mikieo]

In my engineering class, we were told to create a structure out of balsa wood (1/8"x1/8") and glue. The structure has to suport the weight of 3 15lbs. weights (donut shape). We are only give 72" of balsa wood, and the structure must hold the 3 15lbs. weights for 1min. Sorry I am new to this class and engeneering in general but can I plese get some ideas?

Thanks.

 

[JaredJames]

Well what sort of structure do you think you need to be looking at?

What sort of designs are you currently contemplating?

Jared

 

[mikieo]

Well what sort of structure do you think you need to be looking at?

What sort of designs are you currently contemplating?

Jared

I don't have any ideas and I haven't even started yet? so i am open to anything just as long as it is within the rules I said

 

[JaredJames]

Well I can tell you a design that would work almost perfectly, but under the rules of PF I must request you show your attempts and I can only guide you towards the solution.

According to your rules, anything goes with the wood and glue. Although I'd say excessive glue use is outside the spirit of the challenge.

 

[mikieo]

Well I can tell you a design that would work almost perfectly, but under the rules of PF I must request you show your attempts and I can only guide you towards the solution.

According to your rules, anything goes with the wood and glue. Although I'd say excessive glue use is outside the spirit of the challenge.

Well I can't show you my attempts but I can tell you that I tried on a practice run making a base and trying to balance a test book on the balsa wood but it did not work to well...

Oh ya, and I can ONLY use the glue given to me and the wood as well, no extra stuff.

 

[JaredJames]

What are the dimensions of the balsa wood?

 

[mikieo]

What are the dimensions of the balsa wood?

1/8" x 1/8" x 72"

 

[JaredJames]

Is there a minimum size? Or does it just need to hold the three weights? Can the weights sit on top of each other?

 

[mikieo]

Is there a minimum size? Or does it just need to hold the three weights? Can the weights sit on top of each other?

Yes they can sit on top of each other, also the entire thing has to have a width of 8""

 

[JaredJames]

Well it depends on how much time you want to spend on it.

The wood dimensions rule out my original idea.

Assuming no restriction on height, cut 4 strips 8 inches long and 8 strips 3¹⁵/₁₆ long (yeah it's a bit accurate, you'd be better off just using 4 inch strips and ignoring the 1/16 overhang you'll get).

Now:
Lay an 8 inch strip
Put 2 of the shorter strips down to create a cross (should be dead centre).
Lay another 8 inch strip, across the 2 shorter strips so it intercepts the other 8 inch strip in the centre
Lay 2 short strips on the remaining sections of the first 8 inch strip.
Repeat this so you get four layers about an inch high.

You can test it without glue, balance something on the centre (if the weights are round and can sit on top of each other like you say there'll be no problem). Although it will be more rigid with some glue.

It's not the simplest idea, but it will give you good support. The downside is you only get 1 inch in height.

I have a feeling you're looking for something else when you say structure.

 

[mikieo]

Well it depends on how much time you want to spend on it.

The wood dimensions rule out my original idea.

Assuming no restriction on height, cut 4 strips 8 inches long and 8 strips 3¹⁵/₁₆ long (yeah it's a bit accurate, you'd be better off just using 4 inch strips and ignoring the 1/16 overhang you'll get).

Now:
Lay an 8 inch strip
Put 2 of the shorter strips down to create a cross (should be dead centre).
Lay another 8 inch strip, across the 2 shorter strips so it intercepts the other 8 inch strip in the centre
Lay 2 short strips on the remaining sections of the first 8 inch strip.
Repeat this so you get four layers about an inch high.

You can test it without glue, balance something on the centre (if the weights are round and can sit on top of each other like you say there'll be no problem). Although it will be more rigid with some glue.

It's not the simplest idea, but it will give you good support. The downside is you only get 1 inch in height.

I have a feeling you're looking for something else when you say structure.

Uh, there is one problem, it has to be at least 25 inches tall but it can be anything above 25"" but it has to be at least 25 inches tall.

 

[JaredJames]

See, there's more to it. Anything else I should know?

25 inches tall with only 72 inches of wood? That only gives you two supports. How is that going to work?

EDIT: In fact, I don't see how it's possible to create something 25 inches tall with only 72 inches of 1/8th balsa that can support 3kgs.

 

[mikieo]

See, there's more to it. Anything else I should know?

25 inches tall with only 72 inches of wood? That only gives you two supports. How is that going to work?

EDIT: In fact, I don't see how it's possible to create something 25 inches tall with only 72 inches of 1/8th balsa that can support 3kgs.

He says previous classes have done it so...

 

[JaredJames]

He says previous classes have done it so...

To get the 25 inches with that length of would you would either need to cut the wood in a minimum of 2 x 25 inch lengths. Leaving you with one 22 inch length. Not enough to be of use.

A bi-pod, unless perfectly balanced, will not self support.

Perhaps I'm missing something?

 

[JaredJames]

I suppose you could do a bird feeder style affair (I just looked in my garden and was inspired).

Cut two strips to 25 inches.
Stand them vertically.
Cut three/four short pieces that could act as support on the bottom (with the 25 inch pieces still on the floor).
Construct something on top with the remaining to support the weights.

Similar to this:
http://www.alibaba.com/product-gs/331812982/wooden_bird_feeder/showimage.html

But with the centre pieces touching the floor for extra support.

 

[mikieo]

I suppose you could do a bird feeder style affair (I just looked in my garden and was inspired).

Cut two strips to 25 inches.
Stand them vertically.
Cut three/four short pieces that could act as support on the bottom (with the 25 inch pieces still on the floor).
Construct something on top with the remaining to support the weights.

Similar to this:
http://www.alibaba.com/product-gs/331812982/wooden_bird_feeder/showimage.html

But with the centre pieces touching the floor for extra support.

Ok I will do that, I will let you know how it worked out on monday or tuesday.

Thanks for the advice,

Michael

 

[pongo38]

You could double the length available by splitting it down the middle to be 1/8 x 1/16.