Carving Ski Core

[falls]

I am ashamed to admit I am about to make a ski with a 70mm waist.
Going to be a bamboo core
Triax 22oz
Have some uni carbon tape (50mm wide) also
Any thoughts on core thickness in a narrow ski like this in bamboo.
thanks

[skidesmond]

Why the change? I mean that's a narrow ski for powder hounds. 3-12-3 is what I've used with maple and ash wood core. Maybe 2-3 in the tip area. btw - Anything between 70-80 mm is normal where I come from

[falls]

70-80 should be normal for where I come from too!
The 115mm waist isn't ideal for sheet ice and slush bumps!
Trying to make something a bit more tailored to local conditions for a friend. Hopefully can use the same mold (slight tip rocker, camber, traditional tail) for an all mountain (90-95mm waist) ski too.
I am thinking 2-13-2 + some carbon top and bottom of core for the first pair. Rounded flex.

[Brazen]

I think if you use 13mm with 2 x's 22oz and cf top and bottom it will be WAY too stiff. Just my .2 )

[skidesmond]

I don't think you'll need carbon if you're using 22oz FG. What's the length, tip, waist and tail dims and radius? I've made a few skis 168cm 3-12-3 w/ 22 oz FG and they're pretty firm. I'm 195lbs in street cloths. Maybe for a longer ski like a 180cm or longer or if the radius is like 12-14 meters CF might help in firming up the ski.

Keep us posted.

[MontuckyMadman]

but bamboo is super soft. For a ski that narrow i think your layup and core sounds appropriate, considering the weights of YOUR triax in the uni direction the addition of carbon will be good.
Whats the carbon weight 7K, 14K, 5 oz?

[skidesmond]

Ok, I didn't know bamboo was on the soft side, figured it was on the hard side since lot of folks use it.

[Huck Pitueee]

Ok, I didn't know bamboo was on the soft side, figured it was on the hard side since lot of folks use it.

Maybe there are different grades of bamboo. All the bamboo I've worked with ranks in my top 5 of hardness.

[doughboyshredder]

but bamboo is super soft. For a ski that narrow i think your layup and core sounds appropriate, considering the weights of YOUR triax in the uni direction the addition of carbon will be good.
Whats the carbon weight 7K, 14K, 5 oz?

ehhh, don't think so.

Bamboo is more impact resistant than most other woods and has a higher modulus of elasticity.

[falls]

It will be a 177.
124 74 104
Slight early rise tip (27.5cm radius) over 17cm material length.
20cm radius tail over 5th material length.
Sidecut radius 16m or thereabouts.
My fat ski cores (145-115-125) have been bamboo and 2.5-12-2.5 and the skis have tended to come out on the soft side. So was thinking with reduction in width I need a thicker core +/- carbon.

[falls]

It's 200gsm (close to 6oz). 50mm wide 3K uni.

[skidesmond]

but bamboo is super soft. For a ski that narrow i think your layup and core sounds appropriate, considering the weights of YOUR triax in the uni direction the addition of carbon will be good.
Whats the carbon weight 7K, 14K, 5 oz?

ehhh, don't think so.

Bamboo is more impact resistant than most other woods and has a higher modulus of elasticity.

I thought it was hard. It's used for flooring and cutting boards...

The 168cm I made are 120-72-104, with a 3-12-3 ash core and I used 22 oz FG. A real nice carver. They are on the firm side but that's subjective. Never worked w/ CF so I can't say much more stiffer the ski will be.

Maybe I'll add it to my list of Material R+D list.

[MontuckyMadman]

when I say soft I mean in relation to its flexural stiffness longitudinally. An ash or maple plank at the same dims will be way stiffer than a bamboo one in my experience. Say nothing to its impact resistance or janka hardness level.
The youngs moduals for bamboo are higher than that of maple or ash or even pine?
Not the flooring I have. Bends like a grass.
Maybe it dramatically changes when vertically laminated.

There are of course 400 different species of bamboo.

[doughboyshredder]

yeah I think how it's laminated has a huge effect, and like you said there are many different strains of bamboo.

[Brazen]

2 x's 8oz biaxial cf will make a noodle stiffer than 6 stiffs on a stiff-boat. Just as a reference