For the chemists: Cerex and epoxy bond claim

[lemat]

Surfboards are bended sandwich build panels. They break by buckling of compress side, traffic foot dent and others rails ding are accelerator of this end. If you want to improve their bending strengh you have to, in one hand : increase max admissible distorsion of panel,  in other hand : reduce to minimal distorsion under stress but without killing “flex” (ie: the flex of magic board LOL, more seriously dynamic flex defined by Benjamin Thomson years before here). 

So you can: increase skin buckling strengh = increase skin stiffness, the good thing it’s increase dent strengh too, the bad thing it’s quickly a “flex” killer. Or you can : increase core bending stiffness (higher density foam, use of stiffner like stringer ,springer,…), the good thing is stiffening can be more progressive and effective for “flex” the bad thing it’s weight increase quickly and can be not effective for local buckling problems (often initiate by dent).

Come again to the core and skin dilemma, but there is a room to play between the multistringered soft board and the carbon skin surftech. For me the main element is to stay simple so i can master the shape, the process have to be easy, ship and fast.

[huie]

@$1

 

 

if you think about Bert’s original thesis of saturated wood fibers under pressure as a skin it makes allot of sense with all the microscopic hollow veins within the wood fiber being saturated with epoxy. I have the diagram somewhere but I bet most who read it never caught on to what he discovered,

 

 

 

If I merge that with Huie’s nylon mesh fiber underneath  and some veneer to make a natural fiber sandwich skin

and one of our special xps/eps dual cores with a full bamboo mat springer and no wood skins

might be a good next esperiment for the Ewa Beach brother hack squad… thanks for the inpiration mr morey

 

**bernie

when bert was on about that’’  i wrestled with it for some time all sorts of weird experiments/**

**then one day by accident it just jumped up and bit me on the arse

i have worked with it for some time now but most of it has been covered up under the cork decks

bloody Bert sent me through so many doors  but a great journey

who would have thought that for over 40 yrs i worked  the same old way’**

**then the last ten or so  i went to mars haaaaa’’

i will say this i use the nylon grid as it does not interfere with the infusing of the wood and is bonded in to the process

when i used e glass it was distorting the process.**

**cheers huie

 **

 

[volks]

One problem with Kevlar is that it is hydroscopic, I have seen panels get completely delammed jsut because of a small 1/8 dia hole, granted it was in a different industry and somewhat extreme conditions but it is something to consider. All of the repairs I have seen used on panels that use kevlar have required an extened time under vacuum to remove any and all water that creept into the fibers, and a lot of time we just had to cut out anything that had had contact with water and that could be 6 in from the hole in the lam. Just stuff to consider, it really is a cool material.