cheap and crappy is right!
. but seriously, i haven't noticed much of a difference in terms of durability between super-duper high-quality and low-quality wood, except of course, the dent that high-quality wood makes in my bank account. keep in mind that wood does affect the overall weight of a ski, snap, and other characteristics. besides, my skis delam way before the knots become a problem. i put in about 10 days of ski touring on each new pair and i beat them up.
the two new pairs were gifts to friends. they were visiting this past week and wanted to learn to build skis, so i helped out. it was really fun showing them how to build skis. my favorite part was watching them bend and glue the edges. their smiles were bigger than ever when it was time for lay-up, and especially when the final product came out of the press!
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the graphic is simple, as usual. store-bought fabric with printed snow flakes on the pair shown above. glitter was sprinkled over the fabric before the topsheet was laid down. i pressed at 75psi.
as for the knots, i try to keep them away from the binding area. yes, they do fall out sometimes when i profile the core, but i haven't noticed much of a difference. i agree that strength can be compromised, but it's not clear to me exactly how much and whether it's significant. maybe i'll find out someday when i knock out my teeth when a ski snaps in half. modeling the effects of the core with a hole or knot would be interesting. one simple thing we can do is plug a basic core into ANSYS with and without holes --- under three-point bending, for example, and also do a modal analysis --- to observe the difference. i'm sure we'll see a difference, but not sure how much since i haven't done the experiment yet. i believe the other layers make a huge difference too, and maybe they mask the effects of the holes. but i don't know.
like i said for the binding area, i do keep the knots away from there. i've also made skis with an AL binding platform -- a thin sheet of AL which covers the area where the binding is to be mounted. i haven't experienced screws ripping out yet. has anyone experienced this? Kelvin did pull out some screws but he had a pair of foam-core skis.
in the last 6 months i've made over half a dozen pair of skis with the cheapest and crappiest wood possible. the reason is i'm curious. i hope we learn something...
i'll show my latest design sometime this week. it's nothing fancy -- semi-pallet wood mixed with left over pine and fir. AL and some rubber in a few key areas. i'm intrigued by the first few modes of vibration, especially #2.
