foam and/or honeycomb

[Chris Downing]

I have used core cell foam with great luck.

One time I ripped a Danastar SF 197cm tip to tail, then I added about 1inch of corecell foam tip to tail, I lamminated it in with west system, Colloidale silica, and Graphite powder witch also doubled as the base.
The skiied great The epoxy/graphite base worked ok, But without any fiberglass wrap around the foam i was concerned about delame, it never happened I skiied them well over 100 days, hit rocks right on the base across the center stip with equal damege to both materials. core cell is awsome core material.

Corecell™ is a non-friable, tough, rigid, closed-cell SAN* foam with high shear elongation and impact strength. Corecell™ foams retain their mechanical properties even in the higher ambient temperature range. The insulation values are constant over time due to controlled CFC-free foaming process. It is compatible with polyester, vinylester, and epoxy resins and can be thermoformed between 93 - 104 °C. Corecell™ foams are used in sandwich structures to provide low weight, excellent stiffness and structural integrity, under dynamic loads.

Corecell is a tough, damage tolerant foam core. 5 lb. / cu. Ft. density. Excellent for hull and deck core replacement and anywhere that a robust non-wood core is desired. Great for high, dynamically loaded areas. Not good in curved areas.
Sheets are 48" Wide X 85.6" Long.

Corecell advantages:

Stiffness and strength
Very high toughness and impact resistance
Excellent fatigue strength
Sound and thermal insulation
No outgassing
No inhibition
Highly thermoformable
Easy to cut, sand and shape
This material will never rot


Check it out, I like it. But I like wood better, Wood Is Good.

[Truckee Joe]

I am doing a spyder foam ski, vacuum press. i was having problems with using it in a press but with vacuum it seems to not crush at all. I also put in a medal mesh to screw the bindings into. this first ski only had a 60" lenght core, then the ski broke where the tip spacer started.

Now i just cut new cores that will go the entire lenght of the ski. and if this works i want to add some kind of carbon stringer to help add stiffness to the ski.





This is my home made hotwire that I use to cut foam.

[plywood]

nice job! the skis look great. to be hones i don`t trust foam. from my point of view most foams are bad because they collapse under stress sooner or later. i was looking for foam qualified for slalomskateboard building and every foam collapsed sooner or later because of the internal stress due to the shear forces. honeycombs were superior concerning this issue.
the other problem was that neither foam nor honeycomb was very impact resistant. heavy impacts in small areas can cause quite some damage!

with this experiences in the background i can`t wait to hear how your skis last and what you think about using foam

[Truckee Joe]

salomon and atomic have been building foam skis for a while. the suggar daddy is a great ski, I just can't believe how light the ski i made is could be like 2lbs, when i know for sure i'll tell you.

[hugocacola]

I've been thinking about balsa too. But why are you guys thinking about end grain balsa, instead of having the grain run the usual way?

Because balsa grains are like honnycomb if you see at the microscoop, so it will do a very nice performance to your skis...

[TexMurphy]

salomon and atomic have been building foam skis for a while. the suggar daddy is a great ski, I just can't believe how light the ski i made is could be like 2lbs, when i know for sure i'll tell you.

Salomon and Atomic is laying of 400 people because they arnt selling enough skis.... I think that says something about foam skis as they are the only manufactuer that really makes high end foam skis....

Tex

[plywood]

first something about foam: i know that it is possible to build skis with foamcore and that there are manufacturers out there who use foam. as i said, i was looking into different foams with the intend of using them in slalomskateboards. the problem there is that you have much much higher stresses. you basically stand on an 70-80cm long deck with a maybe 7mm core with 2cm of camber that you flatten out when standing on it. this results in quite big shear forces that would rip apart every foam i know.
furthermore the spots where the trucks get mounted are about 8cmx5cm. there a huge pressure gets built up which is problematic for foam.
there are some manufacturers that use foam for their competition slalom skateboards, but all of these boards are stiff as hell so they won`t flex a mm. these "static" sandwich construction avoid shear forces and that`s why they hold. to get such stiff boards they use the hell of a lot composite material - so in the end foamcoare boards are not any lighter than normal decks.
foam consists out of some sort of plastic or whatever you want to call it with small air pockets in it. that`s why it is so light. on impacts in small area these airpockets get compressed and make the "foam" collapse. on such a spot where the foam collapsed also the sandwich construction is weakened and fails, because there is no more core to keep the distance between the sandwich layers.
same with shear forces, which result due to the normal cambering, flexing and decambering while skiing. they result some sort of "fatigue fracture", can cause the air pockets to collapse too. that`s why a lot of the foam CAP-construction skis lost their liveliness after 2,3 years of use.

now for balsa: balsa is amazing. you wouldn`t believe how flexible balsa is! i did some tests once and there i could bend a 1m long 5mm thick balsa stripe in a perfect circle. without any damage and without any decambering afterwards. the only problem with balsa is that it soaks up quite a lot of epoxy and gets heavy if it does soak. for me it worked fine to "impregnate" the wood prior to layup. cover it with a little epoxy and let the epoxy cure, this closes the cells and the wood can`t soak up any more resin but still bonds great.