Thickness???

[NRsciencekid]

What is the best thickness to use for the wood??? Thanks

[thsom]

mostly 1/18, 3/32, 1/16, 1/32, 1/64, 3/16. All varying densities which I'm sure none of us want to reveal. And you have to pick good pieces too test them all as well, not as easy as you think or hope.

[hogger]

^ 1/18 is actually 1/8?

To simplify if you don't cut your own pieces, 1/8 square or 3/32 square for the major legs/posts, and 1/16 square or 1/8 x 1/16 for bracing.

[Balsa Man]

What is the best thickness to use for the wood??? Thanks

I assume you're new to this.

You need to understand, there is no simple answer/no single "best thickness"

If you want to understand why, and what does, or may work, please take the time to read back through at least this year's design discussions - there are lots of different thoughts/combinations/possibilities; specific information from a number of people on what they have successfully used..... Look at the Image Gallery, too- both pictures and discussion/specific information.

Yes, a lot of folk are using 1/8th square, and 1/32nds square wood for the legs. I can tell you that anything over 1/8th is overkill. The real question on legs, is a) bass or balsa, b) what density (at a given size, there is a big variation in strength, depending on density), and c) what intervals you do bracing at (read the discussions this year on how column strength and buckling works). There is some specific information from some on densities used at various sizes
On bracing pieces, there is lots of discussion, lots of variations in approach and sizing- again, read.

[thsom]

^ 1/18 is actually 1/8?

To simplify if you don't cut your own pieces, 1/8 square or 3/32 square for the major legs/posts, and 1/16 square or 1/8 x 1/16 for bracing.

yes, sorry, 1/8 not 1/18, that would be interesting to see and may function as supports actually.

[Littleboy]

What is the best thickness to use for the wood??? Thanks

I assume you're new to this.

You need to understand, there is no simple answer/no single "best thickness"

If you want to understand why, and what does, or may work, please take the time to read back through at least this year's design discussions - there are lots of different thoughts/combinations/possibilities; specific information from a number of people on what they have successfully used..... Look at the Image Gallery, too- both pictures and discussion/specific information.

Yes, a lot of folk are using 1/8th square, and 1/32nds square wood for the legs. I can tell you that anything over 1/8th is overkill. The real question on legs, is a) bass or balsa, b) what density (at a given size, there is a big variation in strength, depending on density), and c) what intervals you do bracing at (read the discussions this year on how column strength and buckling works). There is some specific information from some on densities used at various sizes
On bracing pieces, there is lots of discussion, lots of variations in approach and sizing- again, read.

1/32 for legs? how is that possible?
Also, size is relative to your design.

[Balsa Man]

Oops, bit of a typo; 3/32nds, not 1/32nd....

[foreverphysics]

Oops, bit of a typo; 3/32nds, not 1/32nd....

That is still freakishly small. How in the world are you going to make your tower stand up under than much weight if the legs are that thin and brittle?

[LKN]

Nope. Get your bracing, density, and precision right, you got a tower with 3/32 legs holding the 15kg. Read back through the forum this year and last year, you will see that it is very do-able.

[Balsa Man]

Oops, bit of a typo; 3/32nds, not 1/32nd....

That is still freakishly small. How in the world are you going to make your tower stand up under than much weight if the legs are that thin and brittle?

Nope. Get your bracing, density, and precision right, you got a tower with 3/32 legs holding the 15kg. Read back through the forum this year and last year, you will see that it is very do-able.

LKN is absolutely right-on, on all counts. Detailed answers to your "how in the world??" question are sitting there, waiting to be read and understood.....and used.
As to "that thin...", thin, of course is a relative term; yeah, 3/32nds is thinner than 1/8th; 9/16ths the cross section of 1/8th; at the same density, almost half the weight per unit length. "Brittle?" Not sure where that's coming from; I would certainly not describe 3/32nds bass as "brittle", balsa in that density range is a bit more.

In reading back, key discussion is about column failure, an Euler's Buckling Theorem. If you make/take the time to understand what its all about, and means, you will be a LONG way down the road to doing good towers (or bridges, or boomilevers). Very quick review- take a piece of potential leg wood- 3/32nds or whatever. At a 3 ft length, if you stand it on end, and push down, it buckles with VERY little force. Cut it in half, try again- it takes 4 times the force to buckle it. Cut it in half again, it takes 4x the force (that is 16 times the needed at 3 ft). Bracing, properly done, breaks a long (weak) column in to a series of stacked, shorter columns. Shorten your bracing interval, you get to culumn strength that will carry the load needed. I've posted real data before from column/buckling testing; example- 3/32nds bass at 1.4 grams/24", at a length of 8.5cm), carried over 7 kg. One leg in the chimney of a 4-legged tower (at a 15kg load) only needs to carry just a hair over 3.75kg. So, 4 legs, braced every 8.5cm would be gross overkill. The only limitation is if you get small/low density enough (which will require closely spaced bracing), you get to some point where actual crushing takes place. One could certainly (and successfully) do legs at 1/16th; it would take a lot more bracing than at 3/32nds; probably not a good weight tradeoff.

[TYG]

I'm not quite sure if there is a set answer for this either, but would it be better to use a denser but smaller piece of balsa wood for the cross bracing rather than a less dense but bigger? For example, a stick of balsa wood that weighs 1 gram that is 1/16"x1/16" versus a stick that weighs 1 gram that is 1/16"x1/8", both being the same length?

[SLM]

I'm not quite sure if there is a set answer for this either, but would it be better to use a denser but smaller piece of balsa wood for the cross bracing rather than a less dense but bigger? For example, a stick of balsa wood that weighs 1 gram that is 1/16"x1/16" versus a stick that weighs 1 gram that is 1/16"x1/8", both being the same length?

If the member is a bracing, yes. A 1/16 by 1/16 higher density balsa offers a bit more strength than a 1/16 x 1/8 lower density member.

Say we have a 1/16 x 1/16 low density bracing. Let's refer to the (buckling) strength of the bracing as F1. If we increase the size of the member from 1/16 x 1/16 to 1/16 x 1/8, then the strength increases by a factor of 2. That is, the member would have a strength of 2 * F1. If, however, we double the density of the 1/16 x 1/16 member, its strength increases roughly by a factor of 3. That is, the high density member would have a strength of about 3 * F1.

This analysis, however, does not hold true if the member is a main compression member, not a bracing. If you are designing a main compression member where you are allowed to brace the member, then if you increase the size of the member from 1/16 x 1/16 to 1/16 x 1/8, and you brace it in the weaker direction, then the buckling strength of the member increases by a factor of 8 (buckling strength = 8 * F1). This is a significant improvement over a strength of 3*F1 that you get for doubling the density of the wood.

[Fossil Freak 25]

use mostly 1/16 it works well