Carbon fiber Rods, wide shallow VS thin deep

[killemall8]

From an engineering/ scientific standpoint.

What will make a stiffer neck? a 1/4" x 1/4" square carbon fiber rod, or the standard 1/8" x3/8" rod?

[curtisa]

Thin/deep. A square section of any material is more bendy than a rectangular section of the same material if bent along its narrowest edge. Similar reason to making a laminated neck with the laminations stacked side-by-side vs one on top of the other.

[Bizman62]

1 hour ago, curtisa said:

Thin/deep.

Exactly. Just confirming, there's nothing to add to the explanation.

[ADFinlayson]

A taller one is going to be stiffer in that direction so will certainly make a more effective stiffening rod. That being said, 3/8" is quite tall to be sat either side of a truss rod and I'd be concerned about carving a neck that isn't very girthy. the standard size for carbon fibre in UK seams to be 4mm x 7mm which I think definitely does the job.