Originally Posted by Cirquerider
No ski manufacturer elaborates on the contents or construction of their core any more.
When I stopped selling skis last year, there were still at least two manufacturers who distributed cross sections to hang on the wall and show customers. That is putting the money where the mouth is compared to the often BS explanations you'll find in product literature.
|Could it be that the mass-produced wood laminate blanks being used are just inferior? Probably.
Not my experience. Companies like Fischer produce skis at a fair price with very consistent and carefully machined and laminated cores. I do often wonder how they can do it at the price points they do it at, with European labor, and stay in business. I think you were right the first time...if skiers desire wood cores, manufacturers will make it happen...though the points you make leading to foams are compelling.
Originally Posted by beyond
Could he or someone else explain why laminated strips of wood are stronger and have better flex characteristics than solid? Just don't know the engineering.
(this explanation is meant for someone who knows less about this than you, but I figured what the hey, might as well try and cover the basics.)
Materials like metals tend to be largely isotropic
. That is, they have the same strengths and weaknesses (mechanical properties) in any direction.
Fiberglass, kevlar, and other composite fabrics are anisotropic.
The mechanical properties depend on how you weave the fiber, at what angles, and so on. Chopped mat can closely resemble isotropy, and unidirectional roving (think of a fiber wound tank, pole, etc) has practically all its strength in one direction. These differences are why we hear manufacturers make a big deal about biax, triax, etc.
Wood is an orthotropic
material, so its properties can be described separately in three perpendicular axes. So the strength of wood depends on how the grain is oriented. In skis, quality wood cores are usually what is called vertically laminated
. This means that many carefully selected wood strips are laminated and we cut slices off it for our thin/wide cores. The resulting core has more torsional stiffness (edge grip) than a single piece of wood laid flat would. The manufacturer can laminate alternating species/densities/strengths of wood to create a stiffer/softer core, and they can even do fancier things like change the species at different places along the length of the ski for different flexes, or mill out portions of the core to reduce weight. The downside to all this is that the wood must be of extremely high quality, the processes must be very good, and there is a lot of labor involved.
As to monoblock wood cores: they certainly have a place, but they aren't my cuppa tea.
Originally Posted by spatters
From what I understand, the core provides very little in the way of stiffness to a ski. Mostly it's there to keep the fiberglass layers in shape. It also provides some degree of damping.
This could be anywhere from completely true to completely false depending on the design. Most wood core skis lean towards the false end of that spectrum. Cheap, cheap foam core skis lean towards the true end. At the very minimum the core prevents the cap/base from buckling by taking on a compressive load...think kids foam ski. OTOH, a good wood ski core can be fairly substantial/stiff even before you put a layer of metal on the top and bottom and wrap it in glass.
I think your theories about durability are spot on. Metal skis definitely delaminate/bend/fail more often than similar skis without metal in practice...