ok. we know that full carbon landboards are the busniness and foam/wood core does not cut the mustard. the cores delaminate or cracks.

rather than slam out another glorious carbon deck i'd like to push the envelope and look for a suitable core that will not fail.

so i want something flexible. the board needs to flex 130mm in the center over 950mm without interlaminar shear. this is wear a standard core fails....

so What can i use. it needs to be able to flex as above and be relatively light to afford some weight saving and cheapish to afford some cost savings over a full carbon deck thats massively expensive.

hit me with your ideas

Which foam cracks and delaminates?

Higher density 100-120kg/sqm kledgecel or divinycel or better yet some kiri/pawlonia if you can find a supplier. Alternatively a piece of good poplar or better yet basswood, white maple or ash if you can find something light enough to your tastes. The last three are what are commonly used for ply board decks.

i'm not sure of the foam cores used but am sure they have tried a range including the high density ones. wood just doesn't cut it i can tell that based on the ply core longboard i've made. with the execption of maybe bamboo..... which is very bendy.....
the main problem is interlaminar shear.... i need a substance that will bond with the resin and flex at similar rates to the carbon.......
hmm?

i come from a snowboarding background and know that if you wanted a board to last and retain its 'pop' of life you diddnt buy anything with foam....wood was the only way to go. i have a little burton charger with a full wood core that must be getting on for 10 years old an still hasnt delaminated and still has its pop....i think its just quality workmanship that makes it last, nothing wrong with wood.
funnily enuff balsa is a good choice, bendy but stiff an light as hell.
they tried spring steel but it was toheavy and very dead, same with a lot of plastics...wood just has that life you cant get from anything eles, howcome your cutting it out alltogeather?

I agree with Northernal.
Dont disregard the wood core. Its the benchmark of a solid practical board.
We tried a load of different foam and what didnt completely delaminate creaked and squeaked every time you stepped foot on it. Very annoying.
Keep it simple, that way you know its gonna hold your weight, and stay well away from foam cores unless you are a Guru and have the master plan. (even Spike had loads of probs with this).

I cant wait to see your handywork.

i'm considering bamboo. being a very flexible wood core.
also thinking about polycarbonate aswell.

foam cores are definatly out.

if theres going to be no advantage weight and or cost wise then i'll punch out a full carbon deck.....

bamboo is winning the race so far.

but lurking in the background as an unknown quantity is hemp.... i haven't explored hemp as an option tho it is a very strong natural fibre.

really i'm not one for doing something the same as the last guy so i'm looking to push the limits to see what i can achieve.

however the budget doesn't extend to failures so what ever i do it has to work....

oooh bamboo is doing it for me at the mo

www.bamboo-ply.com/bamboo_ply_new_zealand.asp


aparently you can role the a 1.2x2.4 sheet up into a 250round diameter..... thats plenty flexible.

i'm considering laminating up 4 or 5 layers of the 1mm vaneer.
maybe 2layers of db 400gm and 2 of uni see what happens....

could be the worlds first carbon bamboo landboard

oooh!

Just depends on how cores are used...

As Al and Butch mentions wood cores have been used for years and I've not seen many snowboards fail, bendy as they are. Snowboards vary from very basic sheet of wood to vertical laminated cores using various woods.

I've also seen that bamboo weave at the Plyman here by us. Along with the very expensive long-grain stuff. I'd be a poor man if I picked up all the fancy offcuts from that place by now. :?

Also consider using a capped rail laminate rather than letting the top and bottom laminates bond in the edges forming a rolled rail profile. If a carbon board is meant to be flexy doing the latter is what often propagates a failure as it's the stiffest part of the board. That is why so many kiteboards are cast or plastic capped rail construction. They tend to survive the big kiteloop crashes better.

where is this plyman in auckland? i might try and take a look at it when i'm up next.

i suppose the main differnce between kitesurf boards/snowboard to landboards is that the load is distributed evenly along the length of the surf/snow board so the flex that is accuring and the point loading is alot less than the landboard.

nomex is also being considered but... i don't think thats good for repeaded flex.

sounds like you guys are on another level with the tech eh. just thought i'd jump in and tell you that the hemp board has been done before, so you might be able to get some info on do's and dont's. early californian board company called orb did a hemp core board called the mothership. i've allways wanted to try one, but there like hens teeth to find. they used to make car shells outa cotton, so hemp should be as good if not better. explaining the experimental plantaion in the back garden to the fuzz might not be so easy. :wink:

and also flame boards (current german company) were due to release their first boards as bamboo, but all of a sudden changed there minds and used ply composit (i think) instead. might be worth chatting to them and seeing what changed there minds.

i ride a foam core board and its fooking mint. ground industries conflict. not sure what else there is in there but it rocks. and i'm pretty sure trampa are finally releasing theres. if they can sort out the weight issue they'll be the sickest boards currently on the market.

I got into rod building a while back and the word from flyrod builders is Tonkin cane,it's the 6 million dollar man of bamboo,superior memory,pop,flex blahyaddyblah,it's the shit,check out the old school heat treatment www.canerod.com/Articles/Index.html

The new school use a heat gun

sweet i'm loving the info....
tonkin cane aye! worth considering. tho i don't fancy splitting it and making my own laminations.....

hehe the mothership......

There's one 5 minutes from home:
www.plyman.co.nz/

Nomex is good for large load surfaces like hulls, fuselages and wings but every time your board bounces off any flotsam you'll regret it. You'll have to fill or place solid inserts not just for the through bolts but for the whole surface under a bracket our mounted hardware. Probably under heels etc...

You just have to sit at a halfpipe for a while to realise that snowboards put up with a lot of abuse that is not supported over the length of it. Kiteboards normally have the better deal unless it's shallow or doing lit kiteloops. That is why kiteboard construction changed from wraped or fused rails to capped or cast rails. The interesting thing about woodcore snowboard is that other than the wood and plastics most only have 2 layers of triax and only rely on two strips of carbon in the diagonal for torsional stiffness.

Hemp as a core would be pretty interesting. I've only seen it used as a reinforcement. Similar to cotton it's equal to or stronger than glass. Though it's cool most people stop using it simply because it looks naff in a laminate compared to clear set glass or 2x2 carbons. You know that a most hemp is cultivated from the higher yield drug free members of the same species. Always wanted to try something with flax, cane or some of the giant reeds in the papyrus family. Kiri or palownia is also quite interesting being renewable and a far better choice than balsa or poplar.

Somewhere south of Hamilton someone was also playing around making mountainboards with nycel, foamed PVC as used for sign backing. It's a cheap'ish PVC foam around 100-120kg/sqm density. Though I recall they planed off the solid surface skin using a thicknesser. I used to substitute the same stuff in foam core kiteboards under heels etc.

yes i'm not sold on nomex.... unless i can be convinced otherwise it will be no to nomex.

another idea.

no core at all. hollow center.

space say 2mm carbon apart buy 3-4mm maybe with a carbon stringer or 2........ hmmm

No core, hollow centre means the rail material or joint carries the whole shear modulus for the whole laminate. Even with a stringer it's all determined by the joint rather than spread over the surface.

Curious about the bamboo floorboards too... lots on trademe.

Lets not forget the new foams with integrated carbon pillars like the rohacell derivatives. Expensive though...

give me links to carbon pillared foam cores.

Look up X-Cor and K-Cor, Rohacell based core foams. Consists of a lattice of pulltruded carbon rods suspended in the form before the foam bun is expanded and cured. When sliced to sheets you end up with little carbon pins or pillars in the foam. Similar to what you get when you perforate the foam core for one-shot vacuum molding to the mold to let excess resin seep out through the core.

There was one other that consisted of vertical carbon stringers in the foam but I've longs since lost the link on that. It was something Burton used in their skis or boards for a bit. Instead the laminated sheets of foam with carbon in between and then sliced through it vertically to achieve the stringers. Guess it was an alternative to vertically laminated wood cores.

sounds very intersting.... but expensive. i will research. interestingly that idea had already come to me. but i was unaware it was a buy off the shelf product. mind you my idea wad to use carbon tube bundled together to form the core....

Why not use them as the stringers?

Alternatively if you have a spokeshave to dress some cane and a bandsaw to half them might be just as good. Fancy that, alternate them half round up and half round down with carbon in between and carbon each side so you have fancy carbon corrugated cane filled sheet... that'd be the fruit!

sounds cool but way too much hard work.........

ok heres my latest idea

creating a corregated carbon core

i'd do this by using 5mm platic tube sanwhiched between the carbon and pull them out afterward

it will make a lighter stiffer board but will it fail over time?
how large should the corregations be?... i still want the board super flexi.... only one way to find out.

So this is the idea in my head right now.

400uni carbon
400unicarbon
400db carbon
2 x 400 db carbon corregations around 5mm tube
400db carbon
400uni carbon
400unicarbon

the rails of the board will be super thin so i may run bamboo rails.

maybe replace the 2 x 400 unis with 1 x 600grm

Widthwise or lengthwise corrugations? Stiffness goes up with the radius of the corrugation(same reason as core thickness increases) It might be too stiff to... worth making a sample first. I mean one layer of the thin polycarbonate stuff they use in cheap hothouses holds my weight!

Why not use a light foam as the former rather than a removable plastic form... Just leave it in there. You'd be surprised how hard it is to pull formers out once cured unless heavily waxed or taperred and you only need 1mm to stick to make it impossible to pull it out.

Talking about failure and interlaminate shear: still dependant on the bond of the ridge of each corrugation though... could go trapezoidal to increase that maybe.

length wise. i think that would give me the greatest stiffness.
yes pulling out the tubes could be an issue. rather than mould release i could vas them to ablivious or i could etch them and leave them in there.
i do have some foam i could use instead of the tube. but lets face ut anything other that a square cut will be too hard with my limited hand tools.

yes i understand the sandwiching effect and the exponential increased stiffness with the increased sandwich width. thus the 5mm call. it would make the board around 8mm/9mm thick which is around 2mm more that a full carbon deck. but hell its WAY to hard to do the maths on the actual shear strengths/flex ratios so i will just have to try.

doh! the easy answer for the corregated core is to lay up the core separate to the skins. that way i will easily be able to extract the tube. if it still proves to be hard i can cut,grind etc .....

of course then i will only have a mechanical bond between skins and core..... mind you i'm yet yo have a mechanical bond delaminate.

I don't really know anything about carbon fiber but what if you make your corregations out of bambo sheet then lay your fiber over that. would that work? Or is it even physically possible?

Once again Plummet im really looking forward to seeing what you come up with...

The pure carbon deck would by far be the most simple you could do.. probably followed by bamboo core with carbon top and bottom. As always keep us informed with pictures and such.

yes full carbon would be easy. however i feel the need to try and push the design limits and blaze new territory.

the actual build wont take place for months yet. i need time to contempate and refine my design. as usual failure is not an option.

some vlam bamboo turned up today. so the next board will be bamboo core. just for the fact that i'm lazy and vlam bamboo cf board is very easly to lay up..... if it doesn't ride as well as i like i'll turn it into a longboard skateboard and takle the corregated carbon core board.