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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?

TYG wrote: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.

use mostly 1/16 it works well