Cagey said:ubershallman said:I always thought a scarf joint was supposed to be nice and strong. I was under the impression it was a much better solution than a traditional tilt back design. :dontknow:
It's stronger than a butt joint because you have a larger gluing surface, but there's no mechanical interlock so you're still relying on the strength of the glue and the integrity of the wood. The glue is generally stronger than the wood these days, but wood hasn't changed any. It'll tear along the grain next to the glue joint, rather than the joint itself separating. Because wood has a lot of shear strength perpendicular to the grain, but substantially less parallel to it, you don't often see straight necks busted at the headstock. But, look at the vast majority of broken necks with tilt-back headstocks and you'll most often see they're busted at the scarf joint where parallel stresses exist.
I broke the neck of my acoustic guitar once at the headstock. The scarf joint didn't fail it was a littlebehind that. I suspect most angle headstocks break because when you knock them over the headstock hits hard first.